The efficacy of sotalol in the treatment of sustained ventricular arrhythmias has been proved; however, whether its antiarrhythmic effect is due to a p-blocking activity, a class III antiarrhythmic activity, or a combination of both is not known. We conducted a prospective randomized study to compare the effects of metoprolol, a ''pure'' beta-blocking agent, and of sotalol, a beta-blocking agent with additional class III antiarrhythmic properties, in 34 consecutive patients with documented sustained monomorphic ventricular tachycardia (VT) unrelated to transient causes. After undergoing baseline programmed electrical stimulation (PES-1) to assess arrhythmia inducibility, the patients were randomly assigned to a (double-blind) treatment of either metoprolol (16 patients) or sotalol (18 patients). Before the chronic regimen was initiated, arrhythmia inducibility was reassessed after the intravenous administration of either 0.15 mg/kg metoprolol or 1.5 mg/kg sotalol (PES-2), according to drug assignment. During the chronic oral regimen, a third PES (PES-3) was performed after a median followup of 72 days. Resting and exercise EGG, Holter monitoring and echocardiography were performed at baseline and during follow-up. During a 2-year follow-up, a nonfatal arrhythmia recurred in 1 patient of the metoprolol arm and in 5 patients of the sotalol arm; 1 patient in the latter group died suddenly 2 months after the recurrence, while receiving amiodarone therapy. Intention-to-treat analysis showed no difference in the incidence of arrhythmia recurrence, sudden death, or total mortality between the two groups. During RES-I, a sustained ventricular arrhythmia was inducible in 18 of 34 patients (53%), 8 in the metoprolol and 10 in the sotalol arm. As compared with oral metoprolol, oral sotalol significantly reduced arrhythmia inducibility, but this finding did not correlate with clinical outcome. Neither drug proved superior in preventing the recurrence of spontaneous ventricular arrhythmia or spontaneous or induced ischemic events. Logistic regression showed that gender, age, left ventricular ejection fraction (LVEF), the number of stenotic coronary arteries, and the occurrence of ischemic events did not predict the outcome. Results suggest that metoprolol is as efficacious as sotalol in the treatment of stable monomorphic VT. Whether the treatment of such patients with a pure beta-blocking agent, with a class III antiarrhythmic agent, or with a drug combining both properties may more relevantly affect the clinical outcome in these patients remains to be investigated.
