Which postinfarction ventricular arrhythmias should be treated?

There is still no consensus on which arrhythmias should be treated in the 6- to 12-month high-risk period after acute myocardial infarction. To examine this question, we analyzed 24-hour ECG recordings in 430 patients who survived for at least 2 weeks after myocardial infarction and studied these patients for at least 1 year. During the year after infarction, 63 cardiac deaths occurred. High ventricular premature depolarization (VPD) frequency increased the risk of dying; 26% of the patients had greater than or equal to 10 VPDs/hr and were 2.6 times as likely to die within a year as those with lower frequencies. Repetitive VPDs (pairs or ventricular tachycardia) also were strongly associated with mortality. Thirty-one percent had repetitive VPDs, and these patients were 3.2 times as likely to die as those who lacked this characteristic. Frequent or repetitive VPDs were strongly associated with many other important postinfarction risk factors (e.g., left ventricular dysfunction or digitalis treatment). Nevertheless, frequent or repetitive VPDs contributed significantly to death in the first year after infarction independent of other risk factors; about 90% of these arrhythmias can be controlled satisfactorily with antiarrhythmic drugs. As yet, no definitive trial has been conducted to show whether controlling frequent or repetitive VPDs will significantly reduce the mortality in the first year after infarction. The principal design features for such a trial are discussed.