Risk factors for stroke in chronic atrial fibrillation.

Atrial fibrillation is associated with an increased risk of stroke. Different risk factors may be of importance regarding stroke incidence and mortality in atrial fibrillation. Retrospectively, we studied 786 patients with chronic atrial fibrillation, 229 with rheumatic heart disease and 557 without. In all, 127 patients had stroke (16%). Using Cox's proportional hazard model for failure-time data with age, gender, etiology, degree of heart failure and cardiac enlargement as explanatory (independent) variables, only etiology (rheumatic heart disease) was a significant risk factor for stroke (P less than 0.006). Significant risk factors for death in 653 patients without stroke were age (P = 0.000) and congestive heart failure at the onset of atrial fibrillation (P = 0.000). The need to identify other risk factors for stroke in patients with atrial fibrillation is emphasized, for selecting patients at high risk for prophylactic treatment with anticoagulants or aspirin.