Impact of Anticoagulation before Stroke on Stroke Severity and Long-Term Survival

Abstract

Therapeutic anticoagulation by vitamin K antagonists is highly effective in reducing stroke risk in patients with atrial fibrillation. Vitamin K antagonist treatment before stroke reduces stroke severity and short-term mortality. This study analyses vitamin K antagonists, used in patients with atrial fibrillation diagnosed before the index stroke. We also focus on the impact of preadmission antithrombotic medication on long-term survival. We analyzed 2390 stroke patients consecutively admitted to the Department of Neurology, Charité Berlin, Germany between 2003 and 2004. Mean follow-up was 38 months (range 0-68). Using univariable and multivariable regression models, we identified factors for preadmission anticoagulation in patients with known atrial fibrillation and analyzed the impact of antithrombotic therapy preadmission on functional disability and long-term survival after stroke. Atrial fibrillation was diagnosed in 534 (22·3%) of the 2390 stroke patients. In 348 (65·2%) of all atrial fibrillation patients, atrial fibrillation was already known before the index stroke. Three hundred twenty-five (93·4%) atrial fibrillation patients were amenable to anticoagulation, according to guidelines, 75 (23·1%) received vitamin K antagonists, and 20 (6·2%) had an international normalized ratio of 2-3 at the time of stroke onset. Males and younger patients were more likely to receive anticoagulation preadmission, while previous stroke had no significant impact on vitamin K antagonist prescription. Age (odds ratio 1·02 (95% confidence interval 1·00-1·04) per year), history of coronary artery disease (odds ratio 1·51 (95% confidence interval 1·01-2·26)), and therapeutic anticoagulation (odds ratio 0·28 (0·09-0·84)) were independent predictors of stroke severity. Age (hazard rates 3·11 (95% confidence interval 1·47-6·59), 4·65 (95% confidence interval 2·27-9·57), and 11·1 (95% confidence interval 4·90-25·1) for age categories 65-74, 75-84, and ≥85 years), preadmission antiplatelet therapy (hazard rate 1·85 (95% confidence interval 1·21-2·82)), and stroke severity on admission (hazard rate 1·60 (95% confidence interval 1·03-2·46) and hazard rate 3·23 (95% confidence interval 1·88-5·55) for National Institutes of Health Stroke Scale categories 6-15 and >15 points) were associated with risk of death during follow-up. In patients in which atrial fibrillation was diagnosed prior to the index stroke, about 23% received anticoagulation according to guideline recommendations. Therapeutic anticoagulation at stroke onset significantly decreased the risk of moderate to severe stroke on admission but showed no significant association with long-term survival.