Relationship between infarct volume and prothrombin time-international normalized ratio in ischemic stroke patients with nonvalvular atrial fibrillation

Abstract

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 <1.60 (poor control: PC), 29 patients; PT-INR 1.60–1.99 (low-intensity control: LC), 14 patients; and PT-INR ≥2.00 (high-intensity control: HC), 8 patients. Median (interquartile range: IQR) of infarct volume was 55 mL (IQR 14–175) in the NW, 42 mL (IQR 27–170) in the PC, 36 mL (IQR 6–130) in the LC, and 11 mL (IQR 0–39) in the HC groups. The infarct volume of the HC group was significantly smaller than in the other 3 groups, but no difference existed between the LC and PC groups or the LC and NW groups. Conclusions: Warfarin control at PT-INR of 1.60–1.99 is not effective for reducing the severity of ischemic stroke in NVAF patients.