Management of patients with life-threatening sustained ventricular tachyarrhythmias—The role of guided antiarrhythmic drug therapy

Abstract

Two recent studies have evaluated the utility of electrophysiologic (EP) testing in the treatment of patients with serious ventricular arrhythmias. The first study compared electrophysiologically guided antiarrhythmic drug therapy with nonguided β-blocker therapy. Patients without inducible arrhythmias were assigned to oral metoprolol; patients with inducible arrhythmias were randomly assigned to receive either oral metoprolol or EP-guided drug therapy with propafenone, flecainide, disopyramide, sotalol, or amiodarone. Antiarrhythmic drugs were tested in a random order, but amiodarone was always tested last. A total of 170 patients were evaluated; 115 patients had inducible arrhythmias, and 61 patients were randomly assigned to serial drug testing, 54 to metoprolol without invasive testing, and the remainder who were noninducible to empiric metoprolol. The best outcome was observed in patients without inducible arrhythmias, all of whom received metoprolol. There was no difference in outcome between the two groups with inducible arrhythmias, either treated with metoprolol or with EP-guided serial antiarrhythmic drug testing. The second study evaluated survivors of out-of-hospital ventricular fibrillation (VF) without new myocardial infarction. Patients received assessment of left ventricular ejection fraction, Holter monitoring (HM), and EP testing. Only patients with inducible sustained ventricular arrhythmias or with sufficient ambulatory ventricular ectopy were included in the study. Therapy was randomized either to empiric amiodarone or conventional drug therapy guide by EP testing and/or HM. A total of 228 patients were treated, 113 with amiodarone and 115 with conventional antiarrhythmic drug therapy. The composite primary end points were total mortality, documented out-of-hospital resuscitation from recurrent VF, or syncopal implantable cardioverter/defibrillator shock followed by return of consciousness. Patients treated with empiric amiodarone had a better outcome than did patients treated with guided conventional drug therapy. In those patients in whom an implantable cardioverter/defibrillator was used, patients treated with amiodarone had fewer total shocks and fewer syncopal shocks than did patients treated with conventional therapy. Patients with a history of out-of-hospital VF or sustained ventricular tachycardia without inducible ventricular arrhythmias at EP study have the best outcome. Empiric metoprolol is equivalent to conventional antiarrhythmic drug therapy guided by EP testing. Empiric amiodarone is superior to conventional antiarrhythmic drug therapy guided by HM and/or EP testing.