Congenital long QT syndrome

Congenital long QT syndrome (LQTS) is a group of inherited cardiac channelopathies characterized by prolongation of the QT interval on the electrocardiogram (ECG) and a predisposition to life-threatening ventricular arrhythmias, particularly torsades de pointes. The condition results from dysfunction of cardiac ion channels (potassium, sodium, or calcium channels) that are essential for normal cardiac electrical repolarization. Common synonyms include Romano-Ward syndrome (autosomal dominant forms) and Jervell and Lange-Nielsen syndrome (autosomal recessive form associated with congenital sensorineural deafness). At least 17 genetic subtypes have been identified, with the three most common being LQT1 (KCNQ1 mutations), LQT2 (KCNH2/HERG mutations), and LQT3 (SCN5A mutations), which together account for approximately 75% of genotype-positive cases. The primary body system affected is the cardiovascular system. Key clinical features include recurrent syncope (fainting), seizures, and sudden cardiac arrest or sudden cardiac death, often triggered by physical exertion, emotional stress, auditory stimuli, or occurring during sleep, depending on the genetic subtype. Some individuals remain asymptomatic throughout life, while others may present with cardiac events in infancy, childhood, or adolescence. The severity of the condition is highly variable, even within the same family carrying the same mutation. Treatment options include beta-blocker therapy (particularly nadolol and propranolol), which is the first-line treatment and significantly reduces the risk of cardiac events, especially in LQT1 and LQT2. For patients who remain symptomatic despite beta-blocker therapy or who have experienced cardiac arrest, implantable cardioverter-defibrillators (ICDs) are recommended. Left cardiac sympathetic denervation (LCSD) is an additional therapeutic option for patients who are refractory to beta-blockers or who cannot tolerate them. Sodium channel blockers such as mexiletine may be beneficial specifically in LQT3. Lifestyle modifications, including avoidance of QT-prolonging medications and subtype-specific triggers (e.g., competitive swimming in LQT1, sudden loud noises in LQT2), are essential components of management.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Congenital long QT syndrome