Incidence of persistent atrial fibrillation and conduction defects in coronary heart disease

Abstract

Permanent atrial fibrillation and conduction defects (bundle branch block and A-V block, classified according to Blackburn and associates 10) have been studied in a patient series of 916 patients with coronary heart disease. The following results were obtained: Incidence. The frequency of atrial fibrillation, left and right bundle branch block, and first-degree A-V block was about 2 per cent. A sex- and age-matched correlation of the incidence of these disturbances in our study group with a population study showed astonishing similarities. Furthermore, there was a very low rate of new cases of atrial fibrillation and conduction defects in our patients (1 new case for 70 patient-years). Moreover, only 0.3 per cent of these disturbances persisted after an episode of acute myocardial infarction. Mortality and prognosis. The mortality rate for patients with atrial fibrillation and conduction defects was nearly twice as high as that of the whole study group. The death rate was especially high for patients with atrial fibrillation and left bundle branch block. The average survival time varied from a few months to two years for most patients with atrial fibrillation, bundle branch block, and first-degree A-V block when the probable etiology was coronary heart disease. Etiology. The analysis of possible etiological factors in the present study of atrial fibrillation and bundle branch block showed approximately the same distribution and frequency compared to other studies of large patient series in the literature. The result of this study does not support the widespread opinion that coronary heart disease is the predominant cause of atrial fibrillation and conduction defects, because this outcome was seldom found and rarely developed in our follow-up study of 916 patients with coronary heart disease. Future studies should therefore be directed to look for alternative etiological factors.