Materiały źródłowe

• #1 Diagnosis, management and therapeutic strategies for congenital long QT syndrome | Heart

  https://heart.bmj.com/content/108/5/332

  Congenital long QT syndrome (LQTS) is characterised by heart rate corrected QT interval prolongation and life-threatening arrhythmias, leading to syncope and sudden death. […] In this review, we summarise the current evidence available on the diagnosis, clinical management and therapeutic strategies in LQTS. […] The diagnosis of LQTS relies on the heart rate corrected QT interval (QTc) and on a number of other electrocardiographic parameters as well as elements obtained by history taking (eg, symptoms and family history). Together they form the LQTS probability or Schwartz score, where a score of 3.5 points indicates a high probability of LQTS. […] Genetic information is not part of the Schwartz score but an individual with a pathogenic variant also fulfills the current diagnostic criteria for LQTS.

• #1 Long QT syndrome – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/long-qt-syndrome/diagnosis-treatment/drc-20352524

  To diagnose long QT syndrome (LQTS), a healthcare professional examines you. You are usually asked questions about your symptoms and medical and family history. The health professional listens to your heart with a device called a stethoscope that’s placed against your chest. If your healthcare professional thinks you have an irregular heartbeat, tests can be done to check the heart. […] Tests are done to check the health of the heart and confirm long QT syndrome (LQTS). […] An ECG is the most common test used to diagnose long QT syndrome. It records the electrical signals in the heart and shows how fast or how slow the heart is beating. […] If long QT symptoms don’t happen often, they may not be seen on a regular ECG. If so, your healthcare professional may ask you to wear a heart monitor at home.

• #1 Long QT Syndrome – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441860/

  The QT interval on an electrocardiogram (ECG) represents the duration of the ventricular action potential, and this physiologically correlates with the duration of the ventricular depolarization and repolarization. Cardiac events and fatal arrhythmias may occur when the QT interval is prolonged either congenitally or through acquired causes. This activity reviews the causes of QT prolongation and highlights the role of the interprofessional team in its management. […] Diagnosing prolonged QT starts by measuring the QT interval on ECG. This is often done on lead II or V5-6, whichever is longer. This should be done on several successive beats, of which the longest interval is chosen. If a U wave exists and is large (greater than 1 mm), and fused with T-wave, then this should be included in the QT measurement. On the contrary, if the U-wave is small or separate from the T-wave, then it should be excluded. The maximum slope-intercept method defines the end of the T wave. A helpful tip that helps identify prolonged QT intervals during the initial examination of the ECG is that a normal QT interval should be less than half the preceding RR interval.

• #1 Long QT Syndrome – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441860/

  Due to the variation of QT interval with heart rate (higher heart rate has shorter QT interval, lower heart rate has longer QT interval), it is important to correct the QT interval for the heart rate. This is known as QTc. QTc is prolonged if it is greater than 440 ms in men or greater than 460 ms in women. A QTc greater than 500 is associated with an increased risk of torsade de pointes. While several equations exist to help correct heart rate variation, the Bazett formula (QTC = QT / RR) is the most commonly used. […] In the absence of reversible or acquired causes of QT prolongation, Long QT syndrome is diagnosed. In those patients, obtaining an electrocardiography of the patient and family members may be very helpful. Noncardiac phenotype (as discussed above) may aid in making the diagnosis. Genetic testing of the patient and family members is the gold standard; however, this testing is limited by cost. Pharmacologic provocation with epinephrine or isoproterenol is warranted in patients with a borderline presentation. The concept of this testing is that patients with Long QT syndrome have an abnormal response to sympathetic stimulation. Their ECG shows the failure of the QT interval to shorten with increased heart rates, or it may even show prolongation.

• #1 The Clinical Diagnosis and Management of Long QT Syndrome: Insights from the 2022 ESC Guidelines

  https://www.imrpress.com/journal/RCM/24/6/10.31083/j.rcm2406170/htm

  Long QT syndrome (LQTS) is an uncommon disorder that is characterized by QT prolongation and torsade de pointes leading to sudden cardiac death. […] Since LQTS is rare, it is often underdiagnosed. […] The updated 2022 European Society of Cardiology (ESC) guidelines aim to define the diagnosis of LQTS and spread its management. […] It is recommended that LQTS is diagnosed with either QTc ≥480 ms in repeated 12-lead ECGs with or without symptoms or LQTS diagnostic score >3. […] In patients with clinically diagnosed LQTS, genetic testing and genetic counselling are recommended. […] It is recommended that LQTS is diagnosed in the presence of a pathogenic mutation, irrespective of the QT duration. […] The modified LQTS diagnostic score includes ECG, clinical history, family history and genetic findings; it also contributes to individual risk estimation.

• #1 Diagnosing Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/diagnosis.html

  Long QT syndrome (LQTS) is a rare disorder of the hearts electrical system that can lead to dangerous heart rhythms, fainting, and sudden cardiac arrest. […] We provide expert care for LQTS at the Center for Inherited Cardiovascular Disease. […] Advanced diagnostic services that combine the expertise of electrophysiologists and cardiovascular genetic counselors with cardiac MRI and other screening technologies. […] Genetic counseling services to assess your inherited risk for Long QT syndrome and develop a care plan for you and your family. […] Although there is no cure for LQTS, we can treat the disorder to prevent fainting and dangerous arrhythmias. […] We work with you to customize a treatment plan that supports your health needs. […] At Stanford, we offer comprehensive, specialized testing to confirm a diagnosis of LQTS, including:

• #1 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Pharmacologic provocation with epinephrine or isoproterenol helps in diagnosing LQTS in patients with a borderline presentation. […] It is important to review the ECGs of family members of a patient with LQTS, to obtain detailed histories, and to perform physical examinations. However, an absence of ECG findings of LQTS in family members does not exclude LQTS. […] Genetic testing for known mutations in deoxyribonucleic acid (DNA) samples from patients is becoming accessible in specialized centers, although such tests can entail considerable expense, and insurance coverage for genetic testing often requires specific physician intervention. […] Identification of an LQTS genetic mutation confirms the diagnosis. However, a negative result on genetic testing is of limited diagnostic value, because only approximately 50% of patients with LQTS have known mutations. The remaining half of patients with LQTS may have mutations of yet unknown genes. Therefore, genetic testing has high specificity but low sensitivity.

• #1 Long QT syndrome – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/long-qt-syndrome/diagnosis-treatment/drc-20352524

  A genetic test is available to confirm long QT syndrome (LQTS). The test checks for gene changes that can cause the disorder. […] Genetic tests for long QT syndrome can’t find all inherited cases of long QT syndrome. It’s recommended that families speak to a genetic counselor before and after testing.

• #1 Long QT Syndrome – Melbourne Heart Rhythm

  https://www.melbourneheartrhythm.com.au/learn/conditions/53-long-qt-syndrome

  The main value of genetic testing lies in family screening. Following the identification of a patient (so called “proband”) who unequivocally has LQTS, molecular diagnosis is then sought through screening the known genes. Hundreds of mutations within the genes have been identified, and these genes carry many polymorphisms (harmless genetic variations), so that this first molecular diagnosis is time consuming. However, once the mutation is found, screening for this point mutation in the family is relatively quick. […] The role of beta blockers in those without symptoms, a normal QT interval and yet a positive genetic diagnosis is controversial, since evidence is not yet strong to establish a reduction in risk. Those with a family history of adrenergic induced cardiac events, or known to have LQT1, are most likely to benefit.

• #1 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Relevant guidelines are available from various medical organizations, including but not limited to the following: […] Routinely check serum levels of potassium (and sometimes magnesium) and thyroid function in patients who present with QT prolongation after arrhythmic events, to eliminate secondary reasons for repolarization abnormalities. […] Analysis of repolarization duration (QTc) and morphology on a patient’s electrocardiogram (ECG) and on the ECGs of the patient’s relatives frequently leads to an accurate diagnosis. […] A presentation with syncope or sudden cardiac death, in combination with a long QT interval on an ECG, typically suggests long QT syndrome (LQTS) and leads to genetic testing to diagnose the disease. In many patients, however, the presentation may not be typical. Therefore, other tests may be indicated.

• #1 Acquired long QT syndrome: Clinical manifestations, diagnosis, and management – UpToDate

  https://www.uptodate.com/contents/acquired-long-qt-syndrome-clinical-manifestations-diagnosis-and-management

  Acquired long QT syndrome: Clinical manifestations, diagnosis, and management […] The long QT syndrome (LQTS) is a disorder of myocardial repolarization characterized by a prolonged QT interval on the electrocardiogram (ECG) (waveform 1). This syndrome is associated with a characteristic life-threatening form of polymorphic ventricular tachycardia known as torsades de pointes (TdP) (waveform 2A-B). […] LQTS may be either congenital or acquired. Acquired LQTS usually results from drug therapy (table 1), although other factors such as hypokalemia, hypomagnesemia, and bradycardia can increase the risk of drug-induced LQTS. […] The clinical manifestations, diagnosis, and management of acquired LQTS will be reviewed here. The pathophysiology and causes of acquired LQTS, as well as the clinical manifestations, diagnosis, and management of congenital LQTS, are discussed elsewhere. […] DIAGNOSIS […] Diagnostic criteria […] Differential diagnosis

• #1 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Schwartz et al suggested diagnostic criteria for LQTS in 1993 that still serve as the best criteria for clinicians. […] The most helpful electrocardiographic (ECG) findings are prolongation of the QT interval, the presence of torsade de pointes, the presence of T-wave alternans, and the presence of certain morphology of the T waves (wide-based T wave, and notched T wave in three leads). […] Prolongation of the QTc interval is defined on the basis of age- and sex-specific criteria. QTc prolongation longer than 0.46 seconds indicates an increased likelihood of LQTS. […] In patients with suspected LQTS with borderline QTc values (or even values in the reference range) on standard ECGs or in patients with a score of 2-3 based on the 1993 Schwartz et al diagnostic criteria, an analysis of the dynamic behavior of QTc duration during exercise ECG or long-term Holter monitoring may reveal maladaptation of the QT interval to a changing heart rate.

• #1 Diagnosing Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/diagnosis.html

  Electrocardiogram (EKG), which records the heart’s electrical activity to look for abnormalities. […] Genetic tests, which test the blood for certain genetic markers that may show LQTS. […] Holter and event monitors, portable EKG monitors that record your hearts electrical activity over a longer timeframe. […] Stress test, or exercise EKG, during which you exercise on a treadmill or stationary bicycle.

• #1 Long QT Syndrome (QT Prolongation): Causes, Symptoms, Treatment

  https://www.webmd.com/heart-disease/long-qt-syndrome-overview

  If your doctor thinks you may have long QT syndrome, you’ll get various tests in your doctor’s office or at the hospital. […] You may get an EKG, which graphs your heart’s electrical rhythm. It can be done while you rest or as part of an exercise stress test. Usually, the QT interval lasts about a third of each heartbeat cycle. But with long QT syndrome, this ratio is different. […] Your doctor might do genetic tests or check whether certain medicines trigger LQTS. They might also do tests to see if you have electrolyte imbalances in magnesium, potassium, or calcium. […] You may also need to temporarily wear a device that tracks your heart rhythm as you go about your daily routine. This is done through portable EKGs: Holter monitors can be worn for up to a week and event monitors for up to a few months. Sometimes you may need to have a tiny event monitor inserted under your skin to check for abnormal rhythms that don’t happen very often.

• #1 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Viskin and colleagues demonstrated that the expected shortening of the QT interval in response to sinus tachycardia induced by standing from a supine position is impaired in patients with long QT syndrome (LQTS). […] The increase in QTc in response to standing may persist in patients with LQTS even after heart rate returns to normal.

• #1 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  Congenital LQTS should also be suspected in a person with a prolonged QT in association with a family history of recurrent syncope, seizures or unexplained cardiac arrest at a young age (30 years). […] Pathogenic variants in up to 17 genes have been associated with LQTS. […] The major and most important gene subtypes are LQT1 (KCNQ1 gene), LQT2 (KCNH2 gene), and LQT3 (SCN5A gene) known as LQTS types 1, 2, and 3, respectively. […] Women with LQTS types 1 and 2 are at higher risk of TdP than men with the same mutation, whereas both sexes are equally vulnerable to clinical events with LQTS type 3. […] Treatment with a -blocker is indicated to reduce risk of cardiac events and sudden cardiac death. […] Guidelines for management of ventricular arrhythmias and prevention of sudden cardiac death strongly recommend that in women with LQTS, a -blocker should be continued during pregnancy and the postpartum period regardless of symptoms, including while breastfeeding.

• #1 Long QT Syndrome – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441860/

  The goal of management is the prevention of lethal arrhythmias such as torsade de pointes (TdP). As described earlier, the longer the QT interval, the higher the risk is for torsade de pointes. […] For long-term management in congenital Long QT syndrome, beta-blockers are the first line choice, and they help prevent ventricular arrhythmias by stabilizing ventricular action potential and helping block sympathetic surges associated with arrhythmias. An implantable cardioverter defibrillator (ICD) is recommended in patients with Long QT syndrome who were resuscitated from a cardiac arrest. It is also indicated in those who have beta-blocker-resistant symptoms or have contraindications to beta-blockers. It also may be indicated in asymptomatic individuals who are suspected to be at high risk for ventricular arrhythmias.

• #1 Long QT Syndrome – Melbourne Heart Rhythm

  https://www.melbourneheartrhythm.com.au/learn/conditions/53-long-qt-syndrome

  Family history: If Long QT syndrome is suspected, your doctor will ask a very detailed family history which looks for a history of syncope or sudden unexplained death at a young age in a close relative. Directed questioning is essential, with a family tree being drawn. The history of unexpected drowning in a strong swimmer, or road traffic accidents on a straight road are suggestive of a possible arrhythmic cause. Familial epilepsy and sudden infant death are also suspicious. Any sudden unexpected natural death with a negative post-mortem should trigger a family investigation for LQTS. […] ECGs should then be obtained on all first-degree relatives. Up to one third of asymptomatic gene mutation carriers have QTc values within the normal range. QTc values of 0.44 sec or more are treated as suspicious. Values below 0.41 sec are uncommon in gene carriers. The length of the QT interval is linked to the risk of syncope and sudden death, but all gene carriers are at an increased risk, and can still pass on the mutation to 50% of their children.

• #1 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  Long QT syndrome (LQTS) is a primary genetic and electrical disorder that causes prolongation of ventricular repolarization and increases risk for ventricular arrhythmia-mediated syncope and sudden death. […] After exclusion of secondary causes of QT prolongation, such as hypokalemia or drug-induced causes, a diagnosis of congenital LQTS is made on the basis of a prolonged QT interval on 12-lead ECG followed by commercially available, genetic testing for established LQTS susceptibility genes. The diagnosis of LQTS is sex specific as the QT interval is longer in post-pubertal females than males. […] A prolonged QT (QTc 460 ms for for boys and girls 15 years of age; QTc 470 ms for females and 450 ms for males 15 years of age) along with unexplained syncope is sufficient to diagnose LQTS.

• #1 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  In at least one study, increased risk for cardiac events in the high-risk postpartum period was significantly reduced by -blockers. […] Not all -blockers are equally effective in LQTS. […] The goal should be to minimize side-effects and maximize medication adherence recognizing that side-effects with higher doses may lead to non-adherence. […] The increased risk of cardiac events in LQTS in the 9-month postpartum period is highest in subjects with LQTS with a type 2 mutation. […] Close cardiac follow-up of women with LQT2 mutation during the postpartum period is recommended with serial ECGs every few weeks after delivery in consultation with a cardiologist experienced in LQTS management. […] Treatment with -blockers at adequate doses is of paramount importance in LQT2 patients postpartum. […] Women with congenital LQTS require a team approach involving cardiology and obstetrics before, during and after pregnancy to optimize care and reduce the risk of potentially life-threatening events in the mother, fetus, and baby.

• #1 Primary diagnosis of atrioventricular pseudo-block in a neonate with definitive diagnosis of long QT syndrome: diagnostic considerations and therapeutic approaches | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-025-00827-1

  Long QT syndrome (LQTS) is a potentially lethal medical condition that might never be diagnosed and cause sudden cardiac death. […] The clinical diagnosis of different forms of arrhythmias without genetic testing is not always straightforward and needs a meticulous and thorough evaluation of inherited features through genes. […] It is important to distinguish pseudo-block from LQTS in the neonatal period because a delay in treatment may result in SCD during the neonatal period. […] Early detection of LQTS, which is presented as a pseudo block, especially in neonates, is important because the treatment approach for this rhythmic disorder is completely different from that of congenital heart block. […] Diagnosis typically involves genetic testing to identify mutations and electrocardiography to measure the QT interval.

• #1 Diagnosis, management and therapeutic strategies for congenital long QT syndrome | Heart

  https://heart.bmj.com/content/108/5/332

  It is important to realise that the QTc of individuals with pathogenic variants and normal healthy controls significantly overlap, indicating that a single QTc will never be able to distinguish all non-LQTS ECGs from all LQTS ECGs. […] Based on ECGs of a large number of genotyped LQTS patients and their family members not carrying the familial variant, we designed an online calculator with information on the likelihood that LQTS is present based on the calculated QTc. […] In the past years, additional tools to more reliably assess LQTS on the ECG have been developed, including the use of artificial intelligence in establishing the diagnosis. […] Genetic testing has become an integral part of the diagnosis and management of LQTS patients.

• #1 Congenital long QT syndrome: Diagnosis – UpToDate

  https://www.uptodate.com/contents/congenital-long-qt-syndrome-diagnosis

  Congenital long QT syndrome: Diagnosis […] The ECG features and diagnostic approach to persons with suspected congenital LQTS will be reviewed here. […] Our approach to evaluating the patient with suspected congenital LQTS involves multiple steps: For all patients, the initial evaluation of suspected congenital LQTS should include obtaining a comprehensive personal and family history, performance of a physical examination, and review of multiple ECGs (examination of serial ECGs is extremely helpful). The ECGs are examined to determine both the length of repolarization (the QTc) and the look of repolarization (T wave morphology).

• #1

  https://journals.lww.com/co-cardiology/fulltext/2018/01000/diagnosis_and_clinical_management_of_long_qt.6.aspx

  To give an overview over the substantial advances in the diagnosis and management of Long-QT syndrome since its first description 60 years ago. […] LQT syndrome remains the most common inherited arrhythmia and is a leading cause for sudden unexplained death accounting for up to 2025% of cases. […] Despite all those novel insights, phenotype assessment and appropriate risk stratification in LQT remains challenging even for the expert. […] This review outlines our current understanding and approach to the clinical diagnosis and management of LQT as well as recent insights into genotype-phenotype correlations. […] Genetic testing has evolved beyond a pure diagnostic tool and is in addition increasingly integrated as complementary prognostic marker. […] A specialized inherited arrhythmia clinic is the preferred resource for the complex risk stratification and individualized management of individuals with LQT.

• #1 Types of Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/types.html

  Long QT syndrome (LQTS) is a rare disorder of the hearts electrical system that can lead to dangerous heart rhythms, fainting, and sudden cardiac arrest. […] At Stanford, our internationally renowned electrophysiologists have the skill and experience to provide superior care for this complex condition. […] We provide expert care for LQTS at the Center for Inherited Cardiovascular Disease. […] Advanced diagnostic services that combine the expertise of electrophysiologists and cardiovascular genetic counselors with cardiac MRI and other screening technologies. […] Genetic counseling services to assess your inherited risk for Long QT syndrome and develop a care plan for you and your family. […] Although there is no cure for LQTS, we can treat the disorder to prevent fainting and dangerous arrhythmias.

• #1 Genetic testing reveals new diagnosis for patients originally diagnosed with long QT syndrome – Norton Healthcare Provider Louisville, Ky.

  https://nortonhealthcareprovider.com/news/long-qt-syndrome-and-tachycardia/

  Genetic testing reveals new diagnosis for patient originally presenting with long QT syndrome. […] The case report involves a family whose proband originally presented with syncope and was found to carry a KCNE1 variant implicating long QT syndrome (LQTS), type 5 (LQT5). […] Life-threatening arrhythmias in apparently healthy individuals can be due to diverse heritable cardiac channelopathies. Ongoing advances revealing the underlying pathophysiology and genotype-phenotype associations are constantly evolving our approaches to diagnosis and management of these clinical entities. […] In some cases, initial diagnoses prove inaccurate over time, so routine reevaluation of each patient and family member remains an important element of care, with potentially life-altering ramifications. […] The case report, “One Family’s Clinical Odyssey From Evolving Phenotypic and Genotypic Knowledge of Catecholaminergic Polymorphic Ventricular Tachycardia and Long QT Syndrome,” involves an extended family whose proband originally presented with syncope and was found to carry a KCNE1 variant implicating long QT syndrome (LQTS), type 5 (LQT5).

• #1 Genetic testing reveals new diagnosis for patients originally diagnosed with long QT syndrome – Norton Healthcare Provider Louisville, Ky.

  https://nortonhealthcareprovider.com/news/long-qt-syndrome-and-tachycardia/

  Contemporary genetic testing of the proband identified a variant of uncertain significance (VUS) in RyR2, a more plausible explanation for her phenotype. […] This 20-year experience with a family whose proband presented with syncope and malignant arrhythmias, early on considered to reflect a rare subtype of long QT syndrome after initial genetic testing but later confirmed to be due to CPVT, highlights that providers managing patients with known or suspected inherited arrhythmias should focus primarily on phenotype and consistently reassess contemporary genotype-phenotype correlations to ensure all family members have accurate diagnoses. […] Intermittent reevaluation of family members initially unaffected by the primary genetic variant may be a reasonable practice.

• #2 Long QT Syndrome: Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/17183-long-q-t-syndrome-lqts

  People with long QT syndrome have a QT interval thats longer than normal on an EKG. […] Long QT syndrome is a medical condition that people can pass on from generation to generation. You should get a genetic screening if you have a first-degree relative with long QT syndrome. […] Healthcare providers can diagnose long QT syndrome during a routine electrocardiogram (EKG). To make a diagnosis, they measure the QT interval on the EKG. If your QT interval is longer than 450 milliseconds, you may have long QT syndrome. […] In addition to an electrocardiogram (EKG), testing may include: Blood tests. Genetic testing. Exercise stress test. Ambulatory monitor. […] Long QT syndrome treatments include medications, devices or surgery that help you manage symptoms and prevent sudden death. Treatments dont provide a cure, but can keep you safer from abnormal heart rhythms. […] Long QT syndrome can lead to Torsades de Pointes. This is a life-threatening arrhythmia that can lead to sudden death.

• #2 Long QT Interval Syndromes – Cardiovascular Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmogenic-cardiac-disorders/long-qt-interval-syndromes

  The long QT interval syndromes (LQTS) result from any congenital or acquired disorder of cardiac ion channel function or regulation (channelopathy) that prolongs ventricular myocyte action potential duration as reflected by prolongation of the rate-corrected QT interval on the ECG. […] Diagnosis is by clinical criteria and ECG, sometimes with exercise and/or provocative testing. […] Diagnosis should be considered in patients with unexplained cardiac arrest or syncope or a family history of such when the affected people do not have structural heart disease. […] A long QT interval is diagnosed by ECG showing prolongation of the rate-corrected QT interval (QTc). Normal QTc values are 0.43 second for males and 0.45 second for females and are considered prolonged when 0.45 second for males or 0.47 second for females.

• #2 Long QT syndrome – Symptoms, diagnosis and treatment | BMJ Best Practice US

  https://bestpractice.bmj.com/topics/en-us/829

  A prolonged QT interval is defined as a heart rate-corrected QT interval (QTc) of 450 ms in males and 460 ms in females. […] The European Society of Cardiology suggests using a QTc of 480 ms for diagnosing LQTS and using a QTc of 460-479 as a borderline range where a diagnosis may be considered along with other criteria. […] Key diagnostic factors include history of known gene mutation, use of drugs or circumstances known to increase the QT interval, and syncope during heightened adrenergic tones. […] 1st tests to order include ECG for LQT1, ECG for LQT2, ECG for LQT3, and ECG for hypokalemia and hypomagnesemia. […] Tests to consider include Holter monitor, exercise tolerance test, echocardiography, genetic testing, and epinephrine test.

• #2 The Clinical Diagnosis and Management of Long QT Syndrome: Insights from the 2022 ESC Guidelines

  https://www.imrpress.com/journal/RCM/24/6/10.31083/j.rcm2406170/htm

  QTc ≥480 ms on ECG and pathogenic mutations from genetic findings can solely and independently diagnose LQTS because their respective risk score is >3. […] Genetic testing is essential to avoid genotype-specific triggers, accept genotype-specific treatment for different subtypes, and undergo genetic counselling.

• #2 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Schwartz et al suggested diagnostic criteria for LQTS in 1993 that still serve as the best criteria for clinicians. […] The most helpful electrocardiographic (ECG) findings are prolongation of the QT interval, the presence of torsade de pointes, the presence of T-wave alternans, and the presence of certain morphology of the T waves (wide-based T wave, and notched T wave in three leads). […] Prolongation of the QTc interval is defined on the basis of age- and sex-specific criteria. QTc prolongation longer than 0.46 seconds indicates an increased likelihood of LQTS. […] In patients with suspected LQTS with borderline QTc values (or even values in the reference range) on standard ECGs or in patients with a score of 2-3 based on the 1993 Schwartz et al diagnostic criteria, an analysis of the dynamic behavior of QTc duration during exercise ECG or long-term Holter monitoring may reveal maladaptation of the QT interval to a changing heart rate.

• #2 Diagnosing Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/diagnosis.html

  Electrocardiogram (EKG), which records the heart’s electrical activity to look for abnormalities. […] Genetic tests, which test the blood for certain genetic markers that may show LQTS. […] Holter and event monitors, portable EKG monitors that record your hearts electrical activity over a longer timeframe. […] Stress test, or exercise EKG, during which you exercise on a treadmill or stationary bicycle.

• #2 Diagnosis of Long QT Syndrome: Time to Stand Up! – Revista Española de Cardiología (English Edition)

  https://www.revespcardiol.org/en-diagnosis-of-long-qt-syndrome-time-to-st-articulo-S1885585717302712

  In an original article recently published in Revista Espaola de Cardiologa, Muoz-Esparza et al. report their observations on the value of the stand-up test in the diagnosis of long QT syndrome (LQTS) and its usefulness in guiding patient management. […] However, even in the genetic era, with positive results of genetic testing for approximately 70% of the population, the accuracy of clinical diagnosis, ie, the identification of a prolonged QT interval, represents the mainstay of the diagnosis of LQTS, a potentially lethal disorder for which there is effective therapy. […] Guidelines exist in the literature on which is the best method to measure QT interval and which lead(s) to choose, but less is known on when it should be measured. […] The exercise stress test and 24 hour-ECG holter are probably the best ways to assess the dynamic of the QT interval during the day and night and to evaluate the influence of the autonomic nervous system on the heart.

• #2 Genetics of long-QT syndrome | Journal of Human Genetics

  https://www.nature.com/articles/jhg201574

  Congenital long QT syndrome (LQTS) is an inherited arrhythmia syndrome characterized by a prolonged QT interval in the 12-lead ECG, torsades de pointes and not negligible prevalence of sudden cardiac death. The genetic testing plays an important role in the diagnosis of LQTS. […] The Schwartz score is used to diagnose congenital LQTS. Patients with a Schwartz score 3.5 points in the absence of a secondary cause for QT prolongation are diagnosed with LQTS. […] They reported that congenital LQTS should be diagnosed when the following criteria are fulfilled: […] As just described, the genetic testing is included in the diagnosis criteria and has an important role in the diagnosis of LQTS. […] LQTS genetic testing contributes to not only diagnosis but also gene-specific and mutation-specific risk stratification and patient management.

• #2 Long QT Syndrome – Melbourne Heart Rhythm

  https://www.melbourneheartrhythm.com.au/learn/conditions/53-long-qt-syndrome

  The main value of genetic testing lies in family screening. Following the identification of a patient (so called “proband”) who unequivocally has LQTS, molecular diagnosis is then sought through screening the known genes. Hundreds of mutations within the genes have been identified, and these genes carry many polymorphisms (harmless genetic variations), so that this first molecular diagnosis is time consuming. However, once the mutation is found, screening for this point mutation in the family is relatively quick. […] The role of beta blockers in those without symptoms, a normal QT interval and yet a positive genetic diagnosis is controversial, since evidence is not yet strong to establish a reduction in risk. Those with a family history of adrenergic induced cardiac events, or known to have LQT1, are most likely to benefit.

• #2 Genetic testing for – Blueprint Genetics

  https://blueprintgenetics.com/tests/panels/cardiology/long-qt-syndrome-lqts-panel/

  Is ideal for patients with a clinical suspicion or diagnosis of long QT syndrome. […] Clinical diagnosis is based on patients history, ECG, and family history. Genetic testing is an increasingly important component of the evaluation of LQTS patients. Mutations in cardiac ion-channels can be detected in 75% of patients with clinical diagnosis of LQTS. […] Identification of pathogenic or likely pathogenic variants in dominant disorders or their combinations in different alleles in recessive disorders are considered molecular confirmation of the clinical diagnosis.

• #2 Long QT Syndrome – Melbourne Heart Rhythm

  https://www.melbourneheartrhythm.com.au/learn/conditions/53-long-qt-syndrome

  Long QT syndrome (LQTS) is a familial condition which may be asymptomatic or cause syncope and may cause sudden death through rapid ventricular tachycardia (torsade de pointes), which can deteriorate to ventricular fibrillation, in otherwise fit and healthy young people. Prevalence is approximately 1 in 2,000. […] Clinical diagnosis is made from a combination of suspicious history, family history and the twelve lead ECG, which typically reveals a heart-rate corrected QT interval (QT//R-R interval=QTc) of greater than 0.47 in women and 0.46 in men. QT interval behavior after exercise testing is often helpful in making the diagnosis. […] The diagnosis is usually made on clinical grounds. If the presentation is with syncope or resuscitated sudden cardiac death, the ECG shows QTc prolongation and the T-wave morphology is frequently abnormal. QT prolongation due to drugs or biochemical imbalance (low potassium, calcium or magnesium), hypothermia and myocardial disease must be excluded.

• #2 Long Q-T syndrome – Fraser Health AuthorityLong Q-T syndrome – Fraser Health Authority

  https://www.fraserhealth.ca/health-topics-a-to-z/heart-health/heart-disease/long-q-t-syndrome

  Long Q-T syndrome (LQTS) is a disorder of the heart’s electrical system. It is often inherited and present from birth. It can also be caused by certain medications. […] Your doctor will review your medical history and order an electrocardiogram (ECG) or transesophageal echocardiogram (TEE). LQTS can be hard to diagnose because some patients do not have a visibly prolonged QT interval on an electrocardiogram test. […] Speak to your family doctor about seeing a cardiologist who specializes in cardiac rhythm disorders for further testing. Additional tests may include stress test (exercise tolerance test or ETT) and genetic testing.

• #2 Long QT Syndrome (LQT) | Borderline Prolonged QT Internal Causes

  https://www.radcliffecardiology.com/articles/case-illustrations-long-qt-syndrome?language_content_entity=en

  The Schwartz score, a weighted scoring system incorporating the measured resting QTc interval and other clinical and historical factors, has been used to diagnose LQTS. […] An accurate measurement of the QT interval is valuable in the diagnosis of LQTS, as highlighted in the cases discussed above. […] The QT interval should be determined as a mean value derived from at least three to five cardiac cycles, and is measured from the beginning of the earliest onset of QRS complex to the end of the T-wave. […] When a prolonged QTc is identified after a syncopal event in the absence of acquired causes of QT prolongation, a diagnosis of LQTS can be made, and ECGs should be obtained on all first-degree family members to determine whether others are affected. […] Prolongation of the QT interval on ECG is an essential component for the diagnosis of LQTS, despite its limitations.

• #2 Long QT syndrome – Wikipedia

  https://en.wikipedia.org/wiki/Long_QT_syndrome

  Long QT syndrome may be present at birth or develop later in life. […] LQTS can be diagnosed using an electrocardiogram (EKG) if a corrected QT interval of greater than 450-500 milliseconds is found, but clinical findings, other EKG features, and genetic testing may confirm the diagnosis with shorter QT intervals. […] Diagnosing long QT syndrome is challenging. […] Long QT syndrome is principally diagnosed by measuring the QT interval corrected for heart rate (QTc) on a 12-lead electrocardiogram (ECG). […] LQTS is suggested if the QTc is longer than these cutoffs. […] The major subtypes of inherited LQTS are associated with specific ECG features. […] The Schwartz score has been proposed as a method of combining clinical and ECG factors to assess how likely an individual is to have an inherited form of LQTS. […] In cases of diagnostic uncertainty, other investigations may be helpful to unmask a prolonged QT. […] International consensus guidelines differ on the degree of QT prolongation required to diagnose LQTS.

• #2 Long QT Syndrome | Diagnosis | UK Healthcare

  https://ukhealthcare.uky.edu/gill-heart-vascular-institute/conditions/arrhythmias/long-qt-syndrome/diagnosis

  Your healthcare provider will take several steps to diagnose long QT syndrome. […] Genetic testing may be necessary to determine if you have an inherited form of long QT syndrome. If your test is positive, genetic testing may be recommended for other family members so they can also be diagnosed and treated. […] Blood samples can provide information about your electrolyte and hormone levels. Imbalances of electrolytes and hormones can lead to prolonged QT intervals. […] An electrocardiogram (ECG or EKG) records the electrical activity in your heart through electrodes attached to the body and connected to a machine with wires. […] This device, usually worn for 30 days, allows patients to push a button and record symptoms when they appear. Some event recorders work automatically when irregular heartbeats occur.

• #2 Diagnosis of Long QT Syndrome: Time to Stand Up! – Revista Española de Cardiología (English Edition)

  https://www.revespcardiol.org/en-diagnosis-of-long-qt-syndrome-time-to-st-articulo-S1885585717302712

  It has been known for several years that most LQTS patients have an abnormal QT adaptation to sudden changes in heart rate provoked by brisk standing. […] This simplified version of the bedside stand-up test was thus confirmed to have diagnostic utility and a cutoff of 475ms for QTc standing demonstrated a 90% sensitivity and 100% specificity in differentiating LQTS cases from controls. […] Overall, the study by Muoz-Esparza et al. is welcome because it underlines that, while the mainstay for the diagnosis of LQTS will remain measurement of the QT interval, the practice of measuring the QTc in resting supine conditions may need to be accompanied by the addition of other measurements. […] Furthermore, the possible usefulness for the monitoring of response to therapy and to assess the usefulness of beta blockade appears extremely appealing, though preliminary.

• #2 Long QT Syndrome – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441860/

  Due to the variation of QT interval with heart rate (higher heart rate has shorter QT interval, lower heart rate has longer QT interval), it is important to correct the QT interval for the heart rate. This is known as QTc. QTc is prolonged if it is greater than 440 ms in men or greater than 460 ms in women. A QTc greater than 500 is associated with an increased risk of torsade de pointes. While several equations exist to help correct heart rate variation, the Bazett formula (QTC = QT / RR) is the most commonly used. […] In the absence of reversible or acquired causes of QT prolongation, Long QT syndrome is diagnosed. In those patients, obtaining an electrocardiography of the patient and family members may be very helpful. Noncardiac phenotype (as discussed above) may aid in making the diagnosis. Genetic testing of the patient and family members is the gold standard; however, this testing is limited by cost. Pharmacologic provocation with epinephrine or isoproterenol is warranted in patients with a borderline presentation. The concept of this testing is that patients with Long QT syndrome have an abnormal response to sympathetic stimulation. Their ECG shows the failure of the QT interval to shorten with increased heart rates, or it may even show prolongation.

• #2 Long QT Interval Syndromes – Cardiovascular Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmogenic-cardiac-disorders/long-qt-interval-syndromes

  When a patient has a significantly prolonged QT interval and documented torsade de pointes VT in the absence of other causes of a prolonged QT interval, the diagnosis of a congenital long QT interval syndrome is established. […] Patients with borderline QT intervals suspected of having LQTS should have exercise testing, because some abnormalities appear only during exercise. […] Ambulatory ECG monitoring may also disclose transient ventricular repolarization abnormalities. […] In patients with a normal QTc interval, provocative testing with IV isoproterenol or epinephrine may disclose a concealed long QTc and should be considered in patients with an intermediate probability of a congenital LQTS. […] Because not all patients with a long QT interval have congenital long QT syndrome and because not all patients with a congenital long QT syndrome have a long QT interval on any given ECG, the Schwartz score has been developed to estimate the probability of a congenital LQTS. […] The score can be used to establish candidacy for genetic testing, which can be time-consuming and expensive because of the multiple gene variants to be tested for.

• #2 Long QT Syndrome – with Dr. Anil Gehi | Department of Medicine

  https://www.med.unc.edu/medicine/news/chairs-corner/podcast/long-qt-gehi/

  There are about thirteen of them that have been described, but the most common ones are type 1, type 2, type 3. […] The treatment depends on the severity, so what we’ll do initially when we have a patient who is suspected for Long QT, is we will risk stratify them, and that risk stratification is based on how long their QT interval is. […] If somebody has a very long QT, they are at higher risk of events. […] Genetic testing can also be part of that. […] If you have a severe abnormality, and you, for example, have been resuscitated from a cardiac arrest, we would say you are at high risk for this happening again, and we would recommend a defibrillator, and most patients would be willing to do that. […] It’s actually very good. We have treatments for it, they are very effective. […] As long as the patient takes the beta blocker, then generally they can be very well protected and have a normal life.

• #2 Long QT Syndrome | Advancing Genomic Medicine | Perelman School of Medicine at the University of Pennsylvania

  https://www.med.upenn.edu/agm/long-qt-syndrome

  Long QT syndrome (LQTS) is a cardiac electrophysiologic disorder, characterized by QT prolongation and T-wave abnormalities on the EKG that are associated with tachyarrhythmias. The diagnosis of LQTS is established in a proband with one or more of the following: A risk score of 3.5 in the absence of a secondary cause for QT prolongation […] The presence of a corrected QT interval 500 ms in repeated EKGs in the absence of a secondary cause for QT prolongation […] The identification of a in one of the genes known to be associated with LQTS. Approximately 25% of individuals with LQTS will not have a genetic cause identified on genetic testing.

• #2 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  Congenital LQTS should also be suspected in a person with a prolonged QT in association with a family history of recurrent syncope, seizures or unexplained cardiac arrest at a young age (30 years). […] Pathogenic variants in up to 17 genes have been associated with LQTS. […] The major and most important gene subtypes are LQT1 (KCNQ1 gene), LQT2 (KCNH2 gene), and LQT3 (SCN5A gene) known as LQTS types 1, 2, and 3, respectively. […] Women with LQTS types 1 and 2 are at higher risk of TdP than men with the same mutation, whereas both sexes are equally vulnerable to clinical events with LQTS type 3. […] Treatment with a -blocker is indicated to reduce risk of cardiac events and sudden cardiac death. […] Guidelines for management of ventricular arrhythmias and prevention of sudden cardiac death strongly recommend that in women with LQTS, a -blocker should be continued during pregnancy and the postpartum period regardless of symptoms, including while breastfeeding.

• #2 Long QT syndrome

  https://www.nhs.uk/conditions/long-qt-syndrome/

  Long QT syndrome is diagnosed using an electrocardiogram (ECG), where sensors are put on your chest to check your heart. […] If a GP thinks you could have long QT syndrome, they’ll refer you to a heart specialist (cardiologist) for tests and treatment. […] If you have long QT syndrome, the ECG results will show a pattern in the way your heart beats called a „prolonged QT interval”. […] As long QT syndrome is usually inherited, you may also be offered genetic testing to see if you have genes linked to the condition. […] If you’re diagnosed with long QT syndrome, your immediate family should also be offered testing, as there’s a chance they could also have the condition.

• #2 Long QT Syndrome | Conditions | UCSF Health

  https://www.ucsfhealth.org/conditions/long-qt-syndrome

  Long QT syndrome (LQTS) is usually diagnosed with an electrocardiogram (ECG), which is a picture of the electrical activity of heartbeats. QT refers to a time interval measured on the ECG. People with this disorder have a longer QT interval than other people. […] The ECG isn’t a perfect test for the condition. Some people with the disorder will have normal tests or it might be normal on some days and abnormal on other days. […] LQTS is usually inherited, which means it may affect multiple family members. Each child, sister, or brother of a person with the disorder has a 50 percent chance of inheriting the genetic mutation that causes the condition. […] Once a family member is identified with the condition, it is very important to test all other family members. All close relatives should see a cardiologist and have an ECG.

• #2 Long QT Syndrome – One Heart Cardiology

  https://oneheartcardiology.com.au/service/long-qt-syndrome/

  Family history: If Long QT syndrome is suspected, your doctor will ask a very detailed family history which looks for a history of syncope or sudden unexplained death at a young age in a close relative. Directed questioning is essential, with a family tree being drawn. The history of unexpected drowning in a strong swimmer, or road traffic accidents on a straight road are suggestive of a possible arrhythmic cause. Familial epilepsy and sudden infant death are also suspicious. Any sudden unexpected natural death with a negative post-mortem should trigger a family investigation for LQTS. […] ECGs should then be obtained on all first-degree relatives. Up to one third of asymptomatic gene mutation carriers have QTc values within the normal range. QTc values of 0.44 sec or more are treated as suspicious. Values below 0.41 sec are uncommon in gene carriers. The length of the QT interval is linked to the risk of syncope and sudden death, but all gene carriers are at an increased risk, and can still pass on the mutation to 50% of their children.

• #2 Primary diagnosis of atrioventricular pseudo-block in a neonate with definitive diagnosis of long QT syndrome: diagnostic considerations and therapeutic approaches | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-025-00827-1

  Long QT syndrome (LQTS) is a potentially lethal medical condition that might never be diagnosed and cause sudden cardiac death. […] The clinical diagnosis of different forms of arrhythmias without genetic testing is not always straightforward and needs a meticulous and thorough evaluation of inherited features through genes. […] It is important to distinguish pseudo-block from LQTS in the neonatal period because a delay in treatment may result in SCD during the neonatal period. […] Early detection of LQTS, which is presented as a pseudo block, especially in neonates, is important because the treatment approach for this rhythmic disorder is completely different from that of congenital heart block. […] Diagnosis typically involves genetic testing to identify mutations and electrocardiography to measure the QT interval.

• #2 Primary diagnosis of atrioventricular pseudo-block in a neonate with definitive diagnosis of long QT syndrome: diagnostic considerations and therapeutic approaches | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-025-00827-1

  The identification of mutations has significantly advanced the understanding and management of LQT2, allowing for personalized treatment plans and improved patient outcomes. […] In conclusion, we recommend comprehensive evaluation in neonates with a primary diagnosis of congenital AV block, especially for LQTS. Appropriate and on-time treatment will help prevent undesirable malignant events.

• #2 Long QT Syndrome (LQT) | Borderline Prolonged QT Internal Causes

  https://www.radcliffecardiology.com/articles/case-illustrations-long-qt-syndrome?language_content_entity=en

  Long QT syndrome (LQTS) is a rare potentially life-threatening condition. Physicians must remain vigilant and consider LQTS as a possible etiology in patients with a history of syncope. Prolongation of the QT interval on electrocardiogram (ECG) is an essential component for the diagnosis of LQTS, despite the limitations of this technique. Experience of analyzing the ECG and calculating corrected QTc still remain relevant and are the mainstay diagnostic tools. […] Unfortunately, more than 60% of physicians—even cardiologists—have been known to misinterpret the QT interval on ECG. […] Because of the malignant clinical features of LQTS and the need for a prompt diagnosis that leads to effective treatment, every physician should be aware of its varied clinical presentation and also be able to recognize LQTS on electrocardiogram (ECG).

• #2

  https://journals.lww.com/co-cardiology/fulltext/2018/01000/diagnosis_and_clinical_management_of_long_qt.6.aspx

  To give an overview over the substantial advances in the diagnosis and management of Long-QT syndrome since its first description 60 years ago. […] LQT syndrome remains the most common inherited arrhythmia and is a leading cause for sudden unexplained death accounting for up to 2025% of cases. […] Despite all those novel insights, phenotype assessment and appropriate risk stratification in LQT remains challenging even for the expert. […] This review outlines our current understanding and approach to the clinical diagnosis and management of LQT as well as recent insights into genotype-phenotype correlations. […] Genetic testing has evolved beyond a pure diagnostic tool and is in addition increasingly integrated as complementary prognostic marker. […] A specialized inherited arrhythmia clinic is the preferred resource for the complex risk stratification and individualized management of individuals with LQT.

• #2 An Overview of Diagnosis and Management Strategies for Long QT Syndrome

  https://www.innovationsincrm.com/cardiac-rhythm-management/articles-2017/june/1046-management-strategies-for-long-qt-syndrome

  Significant clinical, research, genetic, and therapeutic advances in the diagnosis and management of long QT syndrome (LQTS) have made the treatment of this channelopathy one of the most exciting and enlightening bench-to-bed success stories in the field of cardiology. […] Here, we present a case of LQTS in a child and a review of the diagnostic and treatment strategies that have been introduced to date in the modern era. […] LQTS is a disease of cardiac repolarization characterized by a prolonged QT interval on the ECG, a risk for syncope, seizures, and sudden death. […] Genetic testing in LQTS has allowed for the development of a better understanding of the phenotype-genotype correlations. […] The patient in the illustrative case was managed in the early 2000s, and her management today would be different.

• #2 An Overview of Diagnosis and Management Strategies for Long QT Syndrome

  https://www.innovationsincrm.com/cardiac-rhythm-management/articles-2017/june/1046-management-strategies-for-long-qt-syndrome

  Nowadays, we have an improved understanding of the overlap between seizures and LQTS, and we would have come to the correct diagnosis more quickly, hopefully before the second cardiac arrest. […] Genetic testing is undertaken early in the course of patient management, as it is clear that knowledge about present genetic mutations affects prognosis and therapy.

• #2 Diagnosing Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/diagnosis.html

  Long QT syndrome (LQTS) is a rare disorder of the hearts electrical system that can lead to dangerous heart rhythms, fainting, and sudden cardiac arrest. […] We provide expert care for LQTS at the Center for Inherited Cardiovascular Disease. […] Advanced diagnostic services that combine the expertise of electrophysiologists and cardiovascular genetic counselors with cardiac MRI and other screening technologies. […] Genetic counseling services to assess your inherited risk for Long QT syndrome and develop a care plan for you and your family. […] Although there is no cure for LQTS, we can treat the disorder to prevent fainting and dangerous arrhythmias. […] We work with you to customize a treatment plan that supports your health needs. […] At Stanford, we offer comprehensive, specialized testing to confirm a diagnosis of LQTS, including:

• #2 Types of Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/types.html

  Long QT syndrome (LQTS) is a rare disorder of the hearts electrical system that can lead to dangerous heart rhythms, fainting, and sudden cardiac arrest. […] At Stanford, our internationally renowned electrophysiologists have the skill and experience to provide superior care for this complex condition. […] We provide expert care for LQTS at the Center for Inherited Cardiovascular Disease. […] Advanced diagnostic services that combine the expertise of electrophysiologists and cardiovascular genetic counselors with cardiac MRI and other screening technologies. […] Genetic counseling services to assess your inherited risk for Long QT syndrome and develop a care plan for you and your family. […] Although there is no cure for LQTS, we can treat the disorder to prevent fainting and dangerous arrhythmias.

• #2 Types of Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/types.html

  We work with you to customize a treatment plan that supports your health needs. […] We discuss these options with you to decide what is right for you. […] Our arrhythmia team includes specialists in inherited cardiovascular disease and genetic counseling and testing. We provide comprehensive care with a compassionate touch for people with long QT syndrome and other inherited arrhythmias.

• #2 Genetic testing reveals new diagnosis for patients originally diagnosed with long QT syndrome – Norton Healthcare Provider Louisville, Ky.

  https://nortonhealthcareprovider.com/news/long-qt-syndrome-and-tachycardia/

  Contemporary genetic testing of the proband identified a variant of uncertain significance (VUS) in RyR2, a more plausible explanation for her phenotype. […] This 20-year experience with a family whose proband presented with syncope and malignant arrhythmias, early on considered to reflect a rare subtype of long QT syndrome after initial genetic testing but later confirmed to be due to CPVT, highlights that providers managing patients with known or suspected inherited arrhythmias should focus primarily on phenotype and consistently reassess contemporary genotype-phenotype correlations to ensure all family members have accurate diagnoses. […] Intermittent reevaluation of family members initially unaffected by the primary genetic variant may be a reasonable practice.

• #3 Long QT Syndrome – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441860/

  The QT interval on an electrocardiogram (ECG) represents the duration of the ventricular action potential, and this physiologically correlates with the duration of the ventricular depolarization and repolarization. Cardiac events and fatal arrhythmias may occur when the QT interval is prolonged either congenitally or through acquired causes. This activity reviews the causes of QT prolongation and highlights the role of the interprofessional team in its management. […] Diagnosing prolonged QT starts by measuring the QT interval on ECG. This is often done on lead II or V5-6, whichever is longer. This should be done on several successive beats, of which the longest interval is chosen. If a U wave exists and is large (greater than 1 mm), and fused with T-wave, then this should be included in the QT measurement. On the contrary, if the U-wave is small or separate from the T-wave, then it should be excluded. The maximum slope-intercept method defines the end of the T wave. A helpful tip that helps identify prolonged QT intervals during the initial examination of the ECG is that a normal QT interval should be less than half the preceding RR interval.

• #3 Long QT syndrome – Wikipedia

  https://en.wikipedia.org/wiki/Long_QT_syndrome

  Long QT syndrome may be present at birth or develop later in life. […] LQTS can be diagnosed using an electrocardiogram (EKG) if a corrected QT interval of greater than 450-500 milliseconds is found, but clinical findings, other EKG features, and genetic testing may confirm the diagnosis with shorter QT intervals. […] Diagnosing long QT syndrome is challenging. […] Long QT syndrome is principally diagnosed by measuring the QT interval corrected for heart rate (QTc) on a 12-lead electrocardiogram (ECG). […] LQTS is suggested if the QTc is longer than these cutoffs. […] The major subtypes of inherited LQTS are associated with specific ECG features. […] The Schwartz score has been proposed as a method of combining clinical and ECG factors to assess how likely an individual is to have an inherited form of LQTS. […] In cases of diagnostic uncertainty, other investigations may be helpful to unmask a prolonged QT. […] International consensus guidelines differ on the degree of QT prolongation required to diagnose LQTS.

• #3 Long QT Interval Syndromes – Cardiovascular Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmogenic-cardiac-disorders/long-qt-interval-syndromes

  When a patient has a significantly prolonged QT interval and documented torsade de pointes VT in the absence of other causes of a prolonged QT interval, the diagnosis of a congenital long QT interval syndrome is established. […] Patients with borderline QT intervals suspected of having LQTS should have exercise testing, because some abnormalities appear only during exercise. […] Ambulatory ECG monitoring may also disclose transient ventricular repolarization abnormalities. […] In patients with a normal QTc interval, provocative testing with IV isoproterenol or epinephrine may disclose a concealed long QTc and should be considered in patients with an intermediate probability of a congenital LQTS. […] Because not all patients with a long QT interval have congenital long QT syndrome and because not all patients with a congenital long QT syndrome have a long QT interval on any given ECG, the Schwartz score has been developed to estimate the probability of a congenital LQTS. […] The score can be used to establish candidacy for genetic testing, which can be time-consuming and expensive because of the multiple gene variants to be tested for.

• #3 Long QT Syndrome Workup: Approach Considerations, Electrocardiography, Genetic Testing

  https://emedicine.medscape.com/article/157826-workup

  Schwartz et al suggested diagnostic criteria for LQTS in 1993 that still serve as the best criteria for clinicians. […] The most helpful electrocardiographic (ECG) findings are prolongation of the QT interval, the presence of torsade de pointes, the presence of T-wave alternans, and the presence of certain morphology of the T waves (wide-based T wave, and notched T wave in three leads). […] Prolongation of the QTc interval is defined on the basis of age- and sex-specific criteria. QTc prolongation longer than 0.46 seconds indicates an increased likelihood of LQTS. […] In patients with suspected LQTS with borderline QTc values (or even values in the reference range) on standard ECGs or in patients with a score of 2-3 based on the 1993 Schwartz et al diagnostic criteria, an analysis of the dynamic behavior of QTc duration during exercise ECG or long-term Holter monitoring may reveal maladaptation of the QT interval to a changing heart rate.

• #3 Diagnosis of Long QT Syndrome: Time to Stand Up! – Revista Española de Cardiología (English Edition)

  https://www.revespcardiol.org/en-diagnosis-of-long-qt-syndrome-time-to-st-articulo-S1885585717302712

  It has been known for several years that most LQTS patients have an abnormal QT adaptation to sudden changes in heart rate provoked by brisk standing. […] This simplified version of the bedside stand-up test was thus confirmed to have diagnostic utility and a cutoff of 475ms for QTc standing demonstrated a 90% sensitivity and 100% specificity in differentiating LQTS cases from controls. […] Overall, the study by Muoz-Esparza et al. is welcome because it underlines that, while the mainstay for the diagnosis of LQTS will remain measurement of the QT interval, the practice of measuring the QTc in resting supine conditions may need to be accompanied by the addition of other measurements. […] Furthermore, the possible usefulness for the monitoring of response to therapy and to assess the usefulness of beta blockade appears extremely appealing, though preliminary.

• #3 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  Congenital LQTS should also be suspected in a person with a prolonged QT in association with a family history of recurrent syncope, seizures or unexplained cardiac arrest at a young age (30 years). […] Pathogenic variants in up to 17 genes have been associated with LQTS. […] The major and most important gene subtypes are LQT1 (KCNQ1 gene), LQT2 (KCNH2 gene), and LQT3 (SCN5A gene) known as LQTS types 1, 2, and 3, respectively. […] Women with LQTS types 1 and 2 are at higher risk of TdP than men with the same mutation, whereas both sexes are equally vulnerable to clinical events with LQTS type 3. […] Treatment with a -blocker is indicated to reduce risk of cardiac events and sudden cardiac death. […] Guidelines for management of ventricular arrhythmias and prevention of sudden cardiac death strongly recommend that in women with LQTS, a -blocker should be continued during pregnancy and the postpartum period regardless of symptoms, including while breastfeeding.

• #3 LQTSG – Overview: Long QT Syndrome Gene Panel, Varies

  https://www.mayocliniclabs.com/test-catalog/Overview/617351

  Providing a genetic evaluation for patients with a personal or family history suggestive of long QT syndrome (LQTS) […] Establishing a diagnosis of LQTS. […] Genetic testing in LQTS is recommended and supported by multiple consensus statements to confirm the clinical diagnosis, assist with risk stratification, guide management, and identify at-risk family members. Even individuals with a normal QT interval may still be at risk for a cardiac event and sudden cardiac death and, thus, ECG analysis alone is insufficient to rule out the diagnosis and genetic testing is necessary to confirm the presence or absence of disease in at-risk family members.

• #3 Long QT Syndrome differential diagnosis – wikidoc

  https://www.wikidoc.org/index.php/Long_QT_Syndrome_differential_diagnosis

  Long QT syndrome is a congenital disease resulting from abnormalities in the ion channels of the heart. Long QT syndrome should be differentiated from secondary QT prolongation. […] Genetic abnormalities cause the Long QT Syndrome. […] Electrolyte disturbances such as hyperkalaemia, hypocalcaemia, hypoglycaemia, hypokalaemia, and hypomagnesemia can cause QT prolongation. […] Subarachnoid hemorrhage and other intracranial events can cause QT prolongation. […] Anorexia nervosa and starvation can cause QT prolongation.

• #3 Long QT Syndrome | Diagnosis | UK Healthcare

  https://ukhealthcare.uky.edu/gill-heart-vascular-institute/conditions/arrhythmias/long-qt-syndrome/diagnosis

  For this test, you will walk on a treadmill or ride a stationary bicycle while connected to heart-monitoring equipment. This test allows us to evaluate electrical changes on the EKG during exercise. […] A patch monitor is a battery-operated ECG that sticks to your chest. While wearing the patch monitor, you can do nearly all your usual activities, even showering. The test usually lasts two to four weeks.

• #3 Genetics of long-QT syndrome | Journal of Human Genetics

  https://www.nature.com/articles/jhg201574

  Congenital long QT syndrome (LQTS) is an inherited arrhythmia syndrome characterized by a prolonged QT interval in the 12-lead ECG, torsades de pointes and not negligible prevalence of sudden cardiac death. The genetic testing plays an important role in the diagnosis of LQTS. […] The Schwartz score is used to diagnose congenital LQTS. Patients with a Schwartz score 3.5 points in the absence of a secondary cause for QT prolongation are diagnosed with LQTS. […] They reported that congenital LQTS should be diagnosed when the following criteria are fulfilled: […] As just described, the genetic testing is included in the diagnosis criteria and has an important role in the diagnosis of LQTS. […] LQTS genetic testing contributes to not only diagnosis but also gene-specific and mutation-specific risk stratification and patient management.

• #3 Long QT Syndrome – with Dr. Anil Gehi | Department of Medicine

  https://www.med.unc.edu/medicine/news/chairs-corner/podcast/long-qt-gehi/

  There are about thirteen of them that have been described, but the most common ones are type 1, type 2, type 3. […] The treatment depends on the severity, so what we’ll do initially when we have a patient who is suspected for Long QT, is we will risk stratify them, and that risk stratification is based on how long their QT interval is. […] If somebody has a very long QT, they are at higher risk of events. […] Genetic testing can also be part of that. […] If you have a severe abnormality, and you, for example, have been resuscitated from a cardiac arrest, we would say you are at high risk for this happening again, and we would recommend a defibrillator, and most patients would be willing to do that. […] It’s actually very good. We have treatments for it, they are very effective. […] As long as the patient takes the beta blocker, then generally they can be very well protected and have a normal life.

• #3 Congenital long QT syndrome during and after pregnancy

  https://www.uscjournal.com/articles/management-long-qt-syndrome-women-during-and-after-pregnancy?language_content_entity=en

  In at least one study, increased risk for cardiac events in the high-risk postpartum period was significantly reduced by -blockers. […] Not all -blockers are equally effective in LQTS. […] The goal should be to minimize side-effects and maximize medication adherence recognizing that side-effects with higher doses may lead to non-adherence. […] The increased risk of cardiac events in LQTS in the 9-month postpartum period is highest in subjects with LQTS with a type 2 mutation. […] Close cardiac follow-up of women with LQT2 mutation during the postpartum period is recommended with serial ECGs every few weeks after delivery in consultation with a cardiologist experienced in LQTS management. […] Treatment with -blockers at adequate doses is of paramount importance in LQT2 patients postpartum. […] Women with congenital LQTS require a team approach involving cardiology and obstetrics before, during and after pregnancy to optimize care and reduce the risk of potentially life-threatening events in the mother, fetus, and baby.

• #3 Genetic testing reveals new diagnosis for patients originally diagnosed with long QT syndrome – Norton Healthcare Provider Louisville, Ky.

  https://nortonhealthcareprovider.com/news/long-qt-syndrome-and-tachycardia/

  Genetic testing reveals new diagnosis for patient originally presenting with long QT syndrome. […] The case report involves a family whose proband originally presented with syncope and was found to carry a KCNE1 variant implicating long QT syndrome (LQTS), type 5 (LQT5). […] Life-threatening arrhythmias in apparently healthy individuals can be due to diverse heritable cardiac channelopathies. Ongoing advances revealing the underlying pathophysiology and genotype-phenotype associations are constantly evolving our approaches to diagnosis and management of these clinical entities. […] In some cases, initial diagnoses prove inaccurate over time, so routine reevaluation of each patient and family member remains an important element of care, with potentially life-altering ramifications. […] The case report, “One Family’s Clinical Odyssey From Evolving Phenotypic and Genotypic Knowledge of Catecholaminergic Polymorphic Ventricular Tachycardia and Long QT Syndrome,” involves an extended family whose proband originally presented with syncope and was found to carry a KCNE1 variant implicating long QT syndrome (LQTS), type 5 (LQT5).

• #3 Congenital long QT syndrome: Diagnosis – UpToDate

  https://www.uptodate.com/contents/congenital-long-qt-syndrome-diagnosis

  Congenital long QT syndrome: Diagnosis […] The ECG features and diagnostic approach to persons with suspected congenital LQTS will be reviewed here. […] Our approach to evaluating the patient with suspected congenital LQTS involves multiple steps: For all patients, the initial evaluation of suspected congenital LQTS should include obtaining a comprehensive personal and family history, performance of a physical examination, and review of multiple ECGs (examination of serial ECGs is extremely helpful). The ECGs are examined to determine both the length of repolarization (the QTc) and the look of repolarization (T wave morphology).

• #3 An Overview of Diagnosis and Management Strategies for Long QT Syndrome

  https://www.innovationsincrm.com/cardiac-rhythm-management/articles-2017/june/1046-management-strategies-for-long-qt-syndrome

  Significant clinical, research, genetic, and therapeutic advances in the diagnosis and management of long QT syndrome (LQTS) have made the treatment of this channelopathy one of the most exciting and enlightening bench-to-bed success stories in the field of cardiology. […] Here, we present a case of LQTS in a child and a review of the diagnostic and treatment strategies that have been introduced to date in the modern era. […] LQTS is a disease of cardiac repolarization characterized by a prolonged QT interval on the ECG, a risk for syncope, seizures, and sudden death. […] Genetic testing in LQTS has allowed for the development of a better understanding of the phenotype-genotype correlations. […] The patient in the illustrative case was managed in the early 2000s, and her management today would be different.

• #3 An Overview of Diagnosis and Management Strategies for Long QT Syndrome

  https://www.innovationsincrm.com/cardiac-rhythm-management/articles-2017/june/1046-management-strategies-for-long-qt-syndrome

  Nowadays, we have an improved understanding of the overlap between seizures and LQTS, and we would have come to the correct diagnosis more quickly, hopefully before the second cardiac arrest. […] Genetic testing is undertaken early in the course of patient management, as it is clear that knowledge about present genetic mutations affects prognosis and therapy.

• #3 Types of Long QT Syndrome | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/long-qt-syndrome/types.html

  Long QT syndrome (LQTS) is a rare disorder of the hearts electrical system that can lead to dangerous heart rhythms, fainting, and sudden cardiac arrest. […] At Stanford, our internationally renowned electrophysiologists have the skill and experience to provide superior care for this complex condition. […] We provide expert care for LQTS at the Center for Inherited Cardiovascular Disease. […] Advanced diagnostic services that combine the expertise of electrophysiologists and cardiovascular genetic counselors with cardiac MRI and other screening technologies. […] Genetic counseling services to assess your inherited risk for Long QT syndrome and develop a care plan for you and your family. […] Although there is no cure for LQTS, we can treat the disorder to prevent fainting and dangerous arrhythmias.

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