Abstract 19565: SAMeTT2R2 Scores Predict Stroke Risk After Initiation of Vitamin K Antagonist Therapy for Atrial Fibrillation: a Real-world Practice Study

Abstract

Introduction: Quality and duration of anticoagulation reflected by high proportion of Time in Therapeutic INR range (TTR) is associated with reduced thrombo-embolic and bleeding events in atrial fibrillation (AF). SAMeTT2R2, a novel score incorporating age, sex, ethnicity, smoking, co-morbidities, and interacting drugs, predicts inadequate anticoagulation control (TTR <0.6) after commencing Vitamin K Antagonist (VKA) for AF, with scores ≥2 suggested as a cut-off to predict inadequate control. Aims: To determine whether SAMeTT2R2 score ≥2 at VKA inception is associated with an increased stroke risk in real-world practice. Methods: A cohort of VKA-naïve patients with incident non-valvular AF between 2001 - 2010 was formed from a large UK primary care database (Clinical Practice Research Datalink, CPRD) with linkage to hospital discharges, and death registry. SAMeTT2R2 score was calculated in a subset of 4468 in whom VKA treatment was initiated within 90 days of AF diagnosis, and scores 0-1, ≥2 were related to 3-year stroke incidence. Competing risk analysis accounting for death was performed to compare the risk of stroke between the two groups in an intention-to-treat analysis. Results: Of 4468 patients with incident AF commenced on VKA (mean age 70.7, 41.2% female), 3422 (76.6%) had a SAMeTT2R2 score of 0-1, and 1046 (23.4%) a score of ≥2. During 3-years 138 patients had a stroke and 58 of these occurred in the year following AF. Cumulative risk estimates for stroke in patients with scores ≥2 compared to 0-1 were significantly increased at 1, 2 and 3 years (log rank test, p<0.01)(Figure). The proportion with TTR≥0.6 was 37.1% for scores ≥2 compared to 44.1% for scores 0-1 (p<0.01). Conclusions: SAMeTT2R2 scores ≥2 predict increased stroke risk in the 3 years following incident AF in patients commenced on VKA treatment. These findings suggest that patients with high SAMeTT2R2 scores may require intensified anticoagulation control or use of oral non-VKA anticoagulants.