Prognosis and management of congenital long QT syndrome
- Peter J Zimetbaum, MD
Peter J Zimetbaum, MD
- Section Editor — Cardiac Arrhythmias
- Professor of Medicine
- Harvard Medical School
- Stephen P Seslar, MD, PhD
Stephen P Seslar, MD, PhD
- Assistant Professor of Cardiology and Pediatrics
- University of Washington
- Charles I Berul, MD
Charles I Berul, MD
- Section Editor — Cardiac Arrhythmias
- Professor of Pediatrics
- George Washington University
- Section Editors
- John K Triedman, MD
John K Triedman, MD
- Section Editor — Pediatric Cardiology
- Professor of Pediatrics
- Harvard Medical School
- Samuel Asirvatham, MD
Samuel Asirvatham, MD
- Section Editor — Long QT Syndrome
- Professor of Medicine and Pediatrics
- Mayo Clinic College of Medicine
The long QT syndrome (LQTS) represents a diverse group of disorders of myocardial repolarization that is characterized by prolongation of the QT interval on the electrocardiogram (ECG). LQTS is important clinically because it is associated with an increased risk of a life-threatening form of polymorphic ventricular tachycardia called torsades de pointes (TdP) or "twisting of points" (waveform 1A-B), syncope and sudden cardiac death.
LQTS can be inherited or acquired. The congenital forms are caused either by autosomal dominant or less often by autosomal recessive genetic mutations, almost all of which encode for abnormal cardiac ion channels (table 1). The acquired forms are caused by a large number of stimuli, most frequently antiarrhythmic and other types of drugs and electrolyte and metabolic abnormalities (table 2). (See "Genetics of congenital and acquired long QT syndrome" and "Acquired long QT syndrome".)
An important distinction between the congenital and acquired forms is that the latter can usually be reversed by correction of the underlying disorder or discontinuation of the offending drug. However, some patients with acquired LQTS have a "forme fruste" of congenital LQTS in which a mutation or polymorphism in one of the LQTS genes is clinically silent until the patient is exposed to a particular drug or other predisposing factor. (See "Acquired long QT syndrome", section on 'Mutations in LQTS genes'.)
The heterogeneity of LQTS makes the diagnosis, therapy, and prognosis of this disorder challenging. Nonetheless, certain guidelines can be made concerning the management of these patients.
The natural history, prognosis, and treatment of congenital LQTS will be reviewed here. Clinical manifestations and criteria for the diagnosis of congenital LQTS and issues related to the management of acquired LQTS are discussed separately. (See "Clinical features of congenital long QT syndrome" and "Diagnosis of congenital long QT syndrome" and "Acquired long QT syndrome".)
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- NATURAL HISTORY AND PROGNOSIS
- Epidemiologic studies
- - International LQTS Registry
- - Italian study
- - International Pediatric Electrophysiology Study
- - Risk factors
- Importance of genotype
- - Clinical course
- - Triggers of arrhythmia
- - Jervell and Lange-Nielsen syndrome
- Untreated versus treated patients
- Influence of pregnancy and menopause
- Patient selection
- Beta blockers
- - Effect of genotype
- Left cardiac sympathetic denervation
- Cardiac pacing
- Implantable cardioverter-defibrillator
- - Use in children
- Targeted pharmacologic therapy
- - Potassium
- - Mexiletine
- - Flecainide
- - Nicorandil
- - Verapamil
- Radiofrequency ablation
- MAJOR SOCIETY GUIDELINES
- INFORMATION FOR PATIENTS
- General measures
- Genotype-specific therapy
- - LQT1
- - LQT3
- Role of beta blockers
- Role of left cardiac sympathetic denervation
- Role of DDD pacing
- Role of ICD