Supraventricular Arrhythmias in Acute Myocardial Infarction

The incidence of supraventricular arrhythmias was evaluated in 350 patients with acute myocardial infarction and was found to be 44%. The mortality among patients with anterior wall myocardial infarction in whom supraventricular arrhythmias occurred was significantly higher (33%) than among those without supraventricular arrhythmias (9%). Among patients with inferior wall infarction the presence of the arrhythmias did not significantly affect the mortality rate (10% versus 7%). Most of the supraventricular arrhythmias developed in the first 48 hours after the infarction, and the incidence of the arrhythmia was greater in patients whose clinical status was worse. Apparently, it is the mechanism producing the arrhythmias that is responsible for the mortality rate associated with them and not the arrhythmias themselves. The importance of the clinical setting of the arrhythmias in evaluating their prognostic or therapeutic implications is reemphasized.