Drug-induced QT prolongation and sudden death

Abstract

Prolongation of the QT interval can predispose to a potentially fatal polymorphic ventricular tachycardia called torsades de pointes (TdP). Although usually self-limited, TdP may degenerate into ventricular fibrillation and cause sudden death. Some medications that cause QT prolongation and possible TdP are commonly used in general practice. This paper presents a case of sudden death that is likely from drug-induced TdP. It reviews the mechanisms, risk factors, offending agents, and management of drug-induced torsades de pointes.

Figure 1

Brief episodes of self-terminating polymorphic ventricular tachycardia were noted after Lidocaine IV bolus was given.

Figure 2

EKG revealed sinus rhythm with no evidence of pre-excitation, no changes consistent with infarction, injury or ischemia, and a QTc of 459 msec.

Figure 3

Drug-induced TdP is usually preceded by a short-long-short ECG sequence.