Secondary prevention after myocardial infarction with class III antiarrhythmic drugs.

First-year mortality after myocardial infarction (MI) is high, amounting to 15%. It has been well documented that ventricular arrhythmias late after MI constitute a risk factor for sudden cardiac death. Consequently, several authors undertook attempts to decrease post-MI mortality with antiarrhythmic drugs. Unfortunately, the class I drugs most widely used in clinical practice proved to be ineffective or they even increased the risk of death, as occurred in the Cardiac Arrhythmia Suppression Trial (CAST). So far, only beta blockers, although not particularly effective in controlling ventricular ectopic beats, have been found to decrease first-year mortality after MI by 26-36%. Class III drugs appear to be promising in this clinical setting. Early study with sotalol showed a positive, although statistically nonsignificant, trend toward decreasing mortality. In a more recent trial with amiodarone (Basel Antiarrhythmic Study of Infarct Survival [BASIS]) done in Switzerland, total mortality was reduced (p < 0.05). It should be stressed that the drug was administered at a low dosage level (200 mg/day) to 98 patients and did not cause serious side effects. Similarly encouraging results have been provided by the Polish Amiodarone Study. Amiodarone given to 305 patients at a low dose (200-400 mg/day) reduced first-year cardiac mortality by 42% (p < 0.05). No serious side effects were noticed. Several ongoing trials should further substantiate the impact of this regimen on mortality after MI.