CONTROL OF REFRACTORY LIFE-THREATENING VENTRICULAR TACHYARRHYTHMIAS BY AMIODARONE

The antiarrhythmic effects and dose-response relationship of amiodarone hydrochloride, 600-1200 mg daily, were studied in 22 patients with recurrent life-threatening symptomatic ventricular tachyarrhythmias refractory to 2 or more conventional antiarrhythmic agents. In all patients the presence of the arrhythmia was confirmed on ECG and/or 24 h Holter readings. In 10, 1 or more episodes of cardiac arrest was documented by ECG. Two patients died prior to initiation or stabilization of therapy; the goal of therapy was attained in all but 1 patient. Amiodarone abolished all complex premature ventricular contractions (PVC) and paroxysmal or sustained episodes of ventricular tachycardia (VT) in all 19 remaining patients; in the 15 in whom predrug and serial 24 h Holter recordings could be obtained and analyzed, the total PVC counts were reduced 90-98% by amiodarone. After a mean follow-up of 12 mo. on chronic amiodarone therapy, there were no recurrences of VT or ventricular fibrillation and sustained antiarrhythmic response was confirmed by Holter recordings. One patient died suddenly at home despite complete suppression of PVC. Amiodarone prolonged the PR (+16.7%; P < 0.05) and QTc (+22.7%; P < 0.01) intervals without effect on QRS duration. Side effects attributable to the drug were gastrointestinal discomfort, halo vision, proximal muscle weakness, transient elevations of hepatic enzymes and skin photosensitivity, all being reversible on reduction in dosage which did not compromise antiarrhythmic efficacy. Amiodarone did not aggravate cardiac failure even in patients with low ventricular ejection fractions. Amiodarone apparently is an extremely potent and safe agent for the prophylactic control of life-threatening ventricular tachyarrhythmias.