Relationship Between Infarct Volume and Prothrombin Time-International Normalized Ratio in Ischemic Stroke Patients With Nonvalvular Atrial Fibrillation

Background:In Japan, warfarin treatment at prothrombin time-international normalized ratio (PT-INR) of 1.60–2.60 is recommended for elderly patients with nonvalvular atrial fibrillation (NVAF). But it remains unknown whether PT-INR 1.60–1.99 has a similar effect on stroke severity as a value >2.0. The purpose of this study was to clarify the association between infarct volume and PT-INR levels.Methods and Results:The 180 patients (mean age, 76 years [SD, 10 years], 53% male) selected from 429 consecutive ischemic stroke patients admitted within 48 h of onset between 2004 and 2014 with NVAF were included. We classified them into 4 groups according to their PT-INR values on admission: no warfarin (NW), 129 patients; PT-INR