Improved late survival and disability after stroke with therapeutic anticoagulation for atrial fibrillation: a population study

Abstract

Background and purpose: Although therapeutic anticoagulation improves early (within 1 month) outcomes after ischemic stroke in hospital-admitted patients with atrial fibrillation, no information exists on late outcomes in unselected population-based studies, including patients with all stroke (ischemic and hemorrhagic).

Methods: We identified patients with atrial fibrillation and stroke in a prospective, population-based study in North Dublin. Clinical characteristics, stroke subtype, stroke severity (National Institutes of Health Stroke Scale), prestroke antithrombotic medication, and International Normalized Ratio (INR) at onset were documented. Modified Rankin Scale (mRS) score was measured before stroke and at 7, 28, and 90 days; 1 year; and 2 years after stroke.

Results: One hundred seventy-five patients had atrial fibrillation-associated stroke and medication data at stroke onset (159 ischemic, 16 hemorrhagic); 17% of those with ischemic stroke were anticoagulated before stroke (27 of 159.) On multivariable analysis, therapeutic INR was associated with improved late survival after ischemic stroke (adjusted 2-year odds ratio for death=0.08; 95% CI, 0.01 to 0.78; P=0.03). This survival benefit persisted when patients with hemorrhagic stroke were included (2-year survival; 70.5% therapeutic INR, 14.3% nontherapeutic INR; log-rank P<0.001; odds ratio for death=0.27; 95% CI, 0.09 to 0.88; P=0.03). Admission INR was inversely correlated with early and late modified Rankin Scale score (2-year Spearman ρ=-0.65; P<0.0003). An INR of 2 to 3 at ischemic stroke onset was associated with greater early (72 hours to 28 days) modified Rankin Scale score improvement (P=0.04) and good functional outcome (modified Rankin Scale score=0 to 2) at 1 year (adjusted odds ratio=4.8; 95% CI, 1.45 to 23.8; P=0.04).

Conclusions: In addition to improving short-term outcome in selected hospital-treated patient groups, therapeutic anticoagulation may provide important benefits for long-term stroke outcomes in unselected populations.