QT prolongation and torsades de pointes associated with concurrent use of cisapride and erythromycin

Prolongation of QT interval may lead to serious, potentially life-threatening, ventricular tachyarrhythmia, such as torsades de pointes. The cause may be an inherited or an acquired malfunction of ion channels at the myocardial cell membrane. Metabolic abnormalities, starvation, nervous system injury, and drug administration cause the much more frequent acquired long QT syndrome (LQTS). Types Ia and III antiarrhythmic drugs account for the majority of these life-threatening events, whereas a number of drugs widely used in otolaryngology, such as antibiotics and antihistamines, have been recently implicated. A case of a life-threatening ventricular tachyarrhythmia after the concurrent administration of cisapride and erythromycin is presented. Reviewed are drugs commonly prescribed in otolaryngology, as well as the associated risk factors that potentially lead to LQTS.