Long QT syndrome.

Long QT syndrome (LQTS) is a clinically and genetically heterogenous syndro me characterized by a lengthening of the QT interval on the surface ECG and a propensity to severe ventricular arrhythmias such as torsades de pointes and ventricular fibrillation, leading eventually to syncope and sudden dea th. This rare syndrome with a mendelian inheritance occurs in subjects with otherwise normal cardiac morphological examination. The potentially severe prognosis justifies a presymptomatic diagnosis. The genetic nature of the disease has been confirmed with the identification of at least six loci and five genes. This syndrome is a perfect illustration of an adrenergic-induc ed ventricular arrhythmia. The first-line treatment is a beta-blocking agen t for all symptomatic patients. In addition, a number of drugs known to len gthen ventricular repolarization must be prohibited. In case of suspicion o f LQTS, all family members should be tested both clinically with a surface ECG and genetically in order to diagnose presymptomatic patients. (C) 2001 editions scientifiques et medicales Elsevier SAS.