Incidence of premature beats and ectopic tachyarrhythmias and their possible interrelation in acute myocardial infarction.

Abstract

Abstract. In a prospective study of patients with acute myocardial infarction the incidence of supraventricular and ventricular ectopic beats and tachyarrhythmias has been examined with regard to the site of the infarcts and a possible interrelation between the different kinds of dysrhythmias. The material consisted of 356 patients consecutively treated and analysed in a Coronary Care Unit (CCU). The mortality rate was 19%. In 68 patients (19%) no ectopic beats or tachycardia were registered. The mortality rate in this group was 13%. In 288 patients with ectopic arrhythmias (81%) the mortality rate was 21%, highest for anterior infarcts. The site of the infarcts was without influence on the frequency of the different kinds of dysrhythmia apart from sinus tachycardia and atrial fibrillation, which were most common in cases of anterior infarct. The incidence of ectopic beats and tachycardias was equal to that found in other CCUs. Supraventricular tachycardias including atrial fibrillation did not influence the mortality rate unless they were part of a pump failure syndrome. A significantly higher frequency of patients with more than 15% supraventricular ectopic beats was found among patients with supraventricular tachycardia than in patients without. No significant interrelation was found between supraventricular and ventricular ectopic beats. In spite of medical treatment a significantly higher frequency of patients with more than 5% ventricular ectopic beats was found in the group with ventricular fibrillation or ventricular tachycardia than in the group without, a tendency that was accentuated if the ectopic beats came in salvoes.