Influence of etiology of atrial fibrillation on incidence of systemic embolism.

Atrial fibrillation is well known to increase greatly the risk of systemic arterial embolism in patients with mitral valve disease. In light of the clinical frequency of embolism in patients with atrial fibrillation due to other types of heart disease, a study was made of embolic occurrences in 333 autopsy patients with atrial fibrillation associated with various kinds of heart disease. Considering only symptomatic emboli with pathologic or surgical confirmation, embolism occurred in 41% of patients with mitral valve disease, 35% of those with ischemic heart disease, 35% of those with coexisting mitral and ischemic heart disease and 17% of those with "other" types of heart disease. Embolism was found in only 7% of a control group of 58 autopsy patients with ischemic heart disease without atrial fibrillation. These findings suggest a high risk of embolism from atrial fibrillation of any origin, but particularly from that caused by ischemic heart disease and mitral valve disease.