Amiodarone and sustained ventricular arrhythmias: statistical evidence of drug effectiveness.

Previous studies have shown that amiodarone prevents sustained ventricular arrhythmias in 77% to 93% of patients. To date, a study using statistical analysis to verify the drug's effectiveness has not been reported. Amiodarone was given to 17 patients with drug refractory sustained ventricular arrhythmias. All patients had serious underlying heart disease including coronary artery disease (15 patients) or cardiomyopathy (two patients). Ten patients had angiographic evidence of a left ventricular aneurysm. All patients had left ventricular dysfunction. The mean left ventricular ejection fraction was 33%. In the 5.5 +/- 8.3 months prior to amiodarone, these 17 patients had documented sustained ventricular arrhythmias requiring countershock (41 episodes), overdrive pacing (four episodes), or intravenous drugs (three episodes). Amiodarone was given as a loading dose (1 gm/day for 10 days) and a maintenance dose (200 to 600 mg/day). During a follow-up period of 8.9 +/- 5.7 months, only eight episodes occurred requiring countershock (5) or overdrive pacing (2); one patient died suddenly. A statistical test constructed for this problem showed a significant (p greater than 0.001) reduced risk of experiencing a sustained ventricular arrhythmia after amiodarone. This statistical model confirms previous studies showing that amiodarone prevents sustained ventricular arrhythmias and prevents sudden cardiac death.