Class III antiarrhythmic agents appear more effective than class I drugs for ventricular tachyarrhythmias, with torsades de pointes occurring in <5% of treated patients.
How can the clinical efficacy of class III antiarrhythmic drugs be evaluated in patients with malignant ventricular tachyarrhythmias?
Serial electrophysiologic testing is a useful invasive method for evaluating the efficacy of class III antiarrhythmic drugs in patients with malignant ventricular tachyarrhythmias.
Summary: Ventricular tachycardia and ventricular fibrillation are frequent complications of organic heart disease. There is sufficient evidence that serial electrophysiologic testing is able to predict long-term efficacy of antiarrhythmic agents in patients with malignant ventricular tachyarrhythmias. This approach has not only been useful for the evaluation of class I drugs, but recent studies have shown that this invasive method may also be useful for the management of patients undergoing treatment with class III antiarrhythmic agents such as amiodarone and sotalol. The results of several studies suggest that class III agents are more effective than class I drugs in patients presenting with ventricular tachycardia or ventricular fibrillation. Proarrhythmic complications in patients treated with class III antiarrhythmic drugs are mainly characterized by torsades de pointes. Their incidence does not exceed 5%. Further studies are necessary to elucidate the mechanisms underlying this type of proarrhythmia. By the use of currently available stimulation techniques, patients who might develop torsades de pointes while on therapy with a class III agent cannot be identified.
Borggrefe et al. (Wed,) conducted a review in Ventricular tachycardia and ventricular fibrillation. Class III antiarrhythmic agents (amiodarone, sotalol) vs. Class I drugs was evaluated. Class III antiarrhythmic agents appear more effective than class I drugs for ventricular tachyarrhythmias, with torsades de pointes occurring in <5% of treated patients.