Atrial fibrillation and stroke: prevalence in different types of stroke and influence on early and long term prognosis (Oxfordshire community stroke project).

OBJECTIVE

To determine in patients with first ever stroke whether atrial fibrillation influences clinical features, the need to perform computed tomography, and prognosis.

DESIGN

Observational cohort study with maximum follow up of 6.5 years.

SETTING

Primary care, based on 10 general practices in urban and rural Oxfordshire.

SUBJECTS

Consecutive series of 675 patients with first ever stroke registered in the Oxfordshire community stroke project.

MAIN OUTCOME MEASURES

Prevalence of atrial fibrillation by type of stroke; effect of atrial fibrillation on case fatality rate and risk of recurrent stroke, vascular death, and death from all causes.

RESULTS

Prevalence of atrial fibrillation was 17% (95% confidence interval 14% to 20%) for all stroke types (115/675), 18% (15% to 21%) for cerebral infarction (97/545), 11% (4% to 11%) for primary intercerebral haemorrhage (7/66), and 0% (0 to 11%) for subarachnoid haemorrhage (0/33). For patients with cerebral infarction the 30 day case fatality rate was significantly higher with atrial fibrillation (23%) than with sinus rhythm (8%); the risk of early recurrent stroke (within 30 days) was 1% with atrial fibrillation and 4% with sinus rhythm. In patients who survived at least 30 days the average annual risk of recurrent stroke was 8.2% (5.9% to 10.9%) with sinus rhythm and 11% (6.0% to 17.3%) with atrial fibrillation.

CONCLUSIONS

After a first stroke atrial fibrillation was not associated with a definite excess risk of recurrent stroke, either within 30 days or within the first few years. Survivors with and without atrial fibrillation had a clinically important absolute risk of further serious vascular events.