Can early effective anticoagulation prevent new lesions on magnetic resonance imaging in acute cardioembolic stroke?

The timing of warfarin administration for acute ischemic stroke (AIS) patients with atrial fibrillation (Af) has not been established. We hypothesized that achieving targeted prothrombin time and international normalized ratio (PT-INR) at 2 weeks could prevent AIS patients with Af from developing a new lesion on diffusion-weighted magnetic resonance imaging (DW-MRI).Of consecutively enrolled AIS patients with Af between 2008 and 2011, we selected the patients who were given warfarin within 2 weeks of admission and had DW-MRI and blood test for PT-INR both on admission and at 2 weeks. Warfarin was started as early as possible and heparin was administered until the targeted PT-INR (2.0-3.0 for patients aged <70 years or 1.6-2.6 for those aged ≥70 years) was achieved.One hundred and twenty-three patients were selected, consisting of 88 patients without a new lesion and 35 patients with a new lesion. Patients with a new lesion had a significantly higher median score on National Institutes of Health Stroke Scale (11.0 vs. 5.5, P = .0053), a lower rate of achieving targeted PT-INR at 2 weeks (25.7% vs. 48.9%, P = .0190), and a lower median dosage of warfarin at 2 weeks (2.0 mg vs. 2.5 mg, P = .0209) than patients without a new lesion. Multivariate logistic regression analysis showed that failure to achieve targeted PT-INR (P = .0298) was significantly associated with the occurrence of a new lesion.Our findings suggest that achieving targeted PT-INR at 2 weeks by using warfarin prevents new lesions in AIS patients with Af.