Congenital and drug-induced long-QT syndrome: an update.

The congenital long-QT syndrome is a potentially life-threatening condition characterised clinically by prolonged QT intervals, syncope and sudden cardiac death. The abnormally prolonged repolarisation is the result of mutations in genes encoding cardiac ion channels. The diagnosis of long-QT syndrome is based on clinical, electrocardiographic, and genetic criteria. Beta-blocking therapy is important in the treatment of long-QT syndrome, although pacemakers and implantable cardioverter defibrillators (ICD) are useful in certain categories of patients. In the near future, mutation-specific treatment will probably become a novel approach to this potentially lethal syndrome. Drug-induced long-QT syndrome has been associated with silent mutations and common polymorphisms in potassium and sodium channel genes associated with congenital long-QT syndrome. Genetic screening for such mutations and polymorphisms may become an important instrument in preventing drug-induced 'torsades de pointes' arrhythmias in otherwise asymptomatic patients.