Arrhythmias in Acute Myocardial Infarction

Abstract

SUMMARY Five hundred admissions for acute myocardial infarction were studied for the incidence of arrhythmias. (The incidence of death in the entire series was 24 per cent). Three hundred and eighty-one patients representing 400 admissions demonstrated an arrhythmia of some type (80 per cent). In those with any arrhythmia, death occurred in 27 per cent; in those without arrhythmia, death occurred in 12 per cent. Serious arrhythmias, however, were accompanied by a death incidence of 47 per cent. The incidence of serious arrhythmias remained relatively constant among all age groups, while the incidence of lesser arrhythmias increased with age. With increasing age, there was a greater incidence of death in those with serious arrhythmias, despite the fact that the incidence of serious arrhythmias remained relatively constant at various ages. Among men with serious arrhythmias there was a 10 per cent higher incidence of death than among women of the same age. The incidence of death in patients having minor arrhythmias or normal rhythm was lower than that for the entire series but increased from 8 to 22 per cent with advancing age. Sex did not alter the incidence of death in this group. Ventricular tachycardia was associated with the highest incidence of death (61 per cent). Sinus bradycardia was associated with a lower incidence of death (11 per cent) than was encountered in the overall series (24 per cent). In sinus tachycardia, the incidence of death (50 per cent) was twice that for the entire series. Among the various anatomic types of infarction, lateral and multiple infarcts were associated with a higher than average incidence of death (68 per cent). Although there was no increased incidence of serious arrhythmias, the incidence of death was greater when serious arrhythmias occurred in these types of infarcts. As compared to the same arrhythmias in association with other anatomic types of infarction this may have resulted from the older age of patients having these infarcts or from the frequent association of these infarcts with altered blood flow to the S-A or A-V node. Hypertension, marked left axis deviation, diabetes mellitus, shocks, and certain other factors did not seem to influence the incidence of death in patients with the various arrhythmias. The treatment of each arrhythmia is briefly discussed, as are the indications and contraindications for the commonly used cardiac drugs.