Selecting the most appropriate patients with atrial fibrillation to be anticoagulated is not always a simple task. Part of helping a patient make an informed decision about such treatment is to discuss the risks of stroke as well as the likely severity of stroke, should it occur. Penado and colleagues conducted a retrospective cohort study to determine the influence of atrial fibrillation on the severity of first-time strokes in patients taking anticoagulants.

Patients were included in the study if they were between 50 and 94 years of age, had a diagnosis consistent with acute cerebrovascular disease, were in atrial fibrillation (sustained or intermittent), were physically independent before the stroke, and had confirmatory computed tomography. Patients were excluded from the study if they had endocarditis or vasculitis, if the stroke was due to a cardiovascular or neurologic surgical procedure, if they had a history of stroke, or if they were taking anticoagulants. Other historical information was collected for each patient. The severity of stroke was determined, and each stroke was classified into one of three groups: fatal, disabling, or nondisabling.

There were 604 patients included in the study, one third of whom had atrial fibrillation. Severe strokes (fatal or disabling) were more likely in those of advanced age, and those with heart failure and atrial fibrillation. Among 205 patients with atrial fibrillation, 12 percent had a fatal stroke, 39 percent had a disabling stroke, and 49 percent had a nondisabling stroke. This finding contrasts with the situations of 399 patients with sinus rhythm, whose rates were 6 percent, 30 percent, and 64 percent, respectively. The odds ratio for increased stroke severity was 2.0 in patients older than 80 years, 2.0 in those with heart failure, and 1.6 in those with atrial fibrillation.

The authors conclude that atrial fibrillation increases the risk of first stroke. Approximately one half of these first-time strokes are fatal or disabling. This information may help physicians discuss the risks and benefits of anticoagulation more completely with their patients.