Importance of QT interval determination and renal function assessment during antiarrhythmic drug therapy.

A major concern associated with the use of antiarrhythmic drugs (AAD) is the occurrence of ventricular proarrhythmia, especially torsade de pointes (TdP). The AADs associated with TdP most commonly include quinidine, procainamide, disopyramide, sotalol, and the newer class III agents, such as ibutilide and dofetilide. It is not simply the administration and nature of an AAD but also several additional factors such as heart rate, ventricular hypertrophy, congestive heart failure, gender, age, concomitant drugs, and impaired drug clearance that influence TdP development. Dosing of these agents should be adjusted to take such factors into account to minimize the incidence of proarrhythmia.