Abstract WP188: Clinical Severity and Timing of Onset for Acute Ischemic Stroke and TIA During Oral Anticoagulation Using Warfarin or Non-vitamin K Antagonist Oral Anticoagulants

Background and Purpose: In Japan, four non-vitamin K antagonist oral anticoagulants (NOACs) became available in clinical use for prevention of stroke in patients with non-valvular atrial fibrillation (NVAF) between 2011 through 2014. The aim of this study is to determine underlying characteristics and ischemic stroke/TIA features of patients taking NOACs or warfarin, a vitamin K antagonist (VKA) prior to stroke/TIA. Methods: We enrolled oral anticoagulant (OAC) users for NVAF, who were admitted to our stroke center for acute ischemic stroke/TIA between March 2011 and June 2015 (ClinicalTrials.gov Identifier: NCT02251665). Results: 381 OAC users who developed stroke/TIA were studied. Of these, 63 patients took NOACs [23 women, 77±9 years, dabigatran in 33 (7 taking higher dosage between two official ones), rivaroxaban in 22 (5), apixaban in 8 (3), edoxaban in none] and 318 took VKA (143 women, 79±8 years). There were no significant differences between NOACs users and VKA users in sex, age, CHADS2 score (median 3[IQR 2-4] vs. 3 [2-4]), history of ischemic stroke/TIA (57% vs. 51%) and prior antiplatelet use (25% vs. 24%). Admission NIHSS score tended to be lower (3 [1-15] vs. 7 [2-20], p=0.076) and discharge NIHSS score was lower (1[0-5] vs 3[1-13], p=0.032) in NOACs users. Discharge mRS (2 [1-4] vs. 3 [1-4]) and mortality during hospitalization (5% vs. 4%) were similar between two groups. A different point was timing of stroke/TIA after initiating OAC ; 6% of NOAC users developed events within 14 days and 32% within 3 months, whereas 4% and 7% of VKA users did, respectively (p<0.001). Congestive heart failure tended to be more common in NOACs users developing events within 3 months than those developing events later (43% vs. 19%, p=0.070). Conclusions: NOACs users tended to show milder neurological deficits than VKA users during acute hospitalization of ischemic stroke/TIA, although discharge mRS was similar. NOACs users often developed stroke/TIA within the initial 3 months after initiating OAC, particularly between 14 days and 3 months. One would take special care of ischemic events during early months after initiating NOACs.