A Therapeutic International Normalized Ratio Results in Smaller Infarcts and Better Outcomes for Patients with Ischemic Stroke

Background: Prior studies have shown that warfarin is effective for both primary and secondary stroke prevention in individuals with atrial fibrillation. It is also known that those on warfarin with atrial fibrillation often have poorer long-term poststroke outcomes, possibly because cardioembolic strokes tend to be larger and more severe. Less is known regarding the direct effect of the international normalized ratio (INR) value at the time of stroke on severity or long-term functional status. Methods: We prospectively followed a consecutive series of 112 patients presenting to our institution with acute ischemic stroke between 2013 and 2018 who were on warfarin. Along with INR on admission, data were collected regarding patient demographics, vascular risk factors, stroke characteristics, and functional outcomes. Patients were stratified by INR into “therapeutic” and “subtherapeutic” groups. Stroke severity (NIH Stroke Scale), infarct volume, and outcome (modified Rankin Scale) were assessed on admission, discharge, and follow-up (3 months poststroke). Differences were calculated using Student's t-tests and regression analyses. Results: The average INR on admission was 1.6 for the entire cohort. Seventy six percent were subtherapeutic on admission (INR < 2.0). Therapeutic patients had lower National Institutes of Health Stroke Scale scores on admission (5.9 versus 9.5, P =.033), significantly smaller stroke volumes (19.5 cc versus 49.2 cc, P =.036), and were more likely to show more than 1 digit improvement on follow-up mRS than subtherapeutic patients. Conclusions: Stroke size and severity is significantly reduced in patients with ischemic strokes who present therapeutic on warfarin. The greater volume of brain saved may ultimately lead to better functional recovery.