Relation of the SAMe-TT2R2 score to quality of anticoagulation control and thromboembolic events in atrial fibrillation patients: Observations from the SPORTIF trials

BACKGROUND: Oral anticoagulant therapy is central to the prevention thromboembolic events in atrial fibrillation (AF) patients. The SAMe-TT2R2 score is a simple clinical-derived score designed to aid decision-making on whether or not a patient is likely to achieve good anticoagulation control on vitamin K Antagonists (VKA, e.g. warfarin). Good anticoagulation control is associated with optimal VKA efficacy and safety. METHODS: The SAMe-TT2R2 score was studied in a large cohort of warfarin-treated non-valvular AF patients from the SPORTIF trials, and related to time in therapeutic range (TTR) as measure of anticoagulation control, and thromboembolism-related outcomes. RESULTS: Among the 3665 patients originally assigned to the warfarin arm, a SAMe-TT2R2 score>2 was found in 19.5%. In these patients, a linear relationship was reported between SAMe-TT2R2 score and TTR (p<0.001). SAMe-TT2R2>2 was inversely associated with a higher proportion with TTR >65% (p=0.014) or TTR >70% (p=0.011). Patients with SAMe-TT2R2 score>2 had a significantly higher event rate of the composite thromboembolism-related outcome, vs. SAMe-TT2R2 0-2 (10.2% vs. 7.9%, p=0.045). On survival analysis, SAMe-TT2R2>2 was associated with a higher risk for the composite outcome (Log-Rank: 5.471, p=0.019). On Cox regression, a SAMe-TT2R2 score>2 was independently associated with the composite outcome (p=0.020). CONCLUSIONS: In this large trial cohort of AF patients, the SAMe-TT2R2 score was able to identify patients more likely to obtain suboptimal anticoagulation control on VKA, with an increase in major thromboembolism-related adverse events consequent upon such poor anticoagulation control.