ACQUIRED PROLONGED QT INTERVAL AND TORSADES-DE-POINTES INDUCED BY ERYTHROMYCIN

Erythromycin can induce prolongation of the QT interval on the ECG with a risk of << torsades de pointes >>. Fourteen such cases have been reported in the literature. In vitro and in vivo electrophysiologic studies have shown that this antibiotic has concentration-dependent effects on cardiac fibers similar to those of antiarrhythmic agents belonging to the Vaughan-Williams class Ia. However, this adverse effect is only very infrequently seen with this widely used drug and seems to occur in patients with other factors promoting prolongation of the QT interval.