Clinical study of nibentan - New class III antiarrhythmic drug .3. Efficacy in patients with ventricular arrhythmias; Arrhythmogenic effects

Efficacy of a new class III antiarrhythmic drug nibentan for suppression of ventricular arrhythmias and its proarrhythmic effects in various cardiac rhythm disturbances were studied in 29 patients with frequent high grade ventricular premature beats and in 42 patients with atrial premature beats, supraventricular tachycardia, atrial fibrillation and flutter. In 54 patients underlying heart disease was revealed and in 17 patients arrhythmias were idiopathic. None of the patients had conduction disturbances or heart failure. Nibentan was injected intravenously as 1 - 3 boluses with 15 minute intervals. Total dose was 0, 125 - 0,5 mg/kg. Methods of investigation included conventional 12-lead and Holter 24-hour ECG and ECG monitoring in coronary care unit. Nibentan produced pronounced antiarrhythmic effect in 57% of patients with frequent and coupled ventricular premature beats and with paroxysmal unsustained ventricular tachycardia. Rate of proarrhythmic effects in patients with ventricular arrhythmias was high and average effective and average arrhythmogenic doses were equal. These data precluded recommendation of a wide use of the drug in these rhythm disturbances. Proarrhythmic effects were observed in 8% of patients with supraventricular tachycardia, atrial fibrillation and flutter mainly during periods of sinus rhythm. No proarrhythmic effects were registered in patients with paroxysmal supraventricular arrhythmias.