Dabigatran Superior to Warfarin in Patients with Atrial Fibrillation and Lower CHA2DS2-VASc Scores

NEW ORLEANS, LA—Dabigatran 150mg was superior to warfarin and dabigatran 110mg was noninferior to warfarin for preventing stroke in patients with atrial fibrillation (AF) regardless of CHA2DS2-VASc scores, as shown by the results of a subgroup analysis of 18,113 patients enrolled in the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial presented today by Jonas Oldgren, MD and colleagues from the Uppsala Clinical Research Center in Uppsala, Sweden, at ACC.11, the American College of Cardiology's 60th Annual Scientific Session.

Risk of stroke in patients with AF can be influenced by comorbidities, and assessing risk stratification among myriad risk factors can be expressed as the CHA2DS2-VASc score. This acronym details the factors for which scores are assigned: 1 for congestive heart failure/left ventricular dysfunction; 1 for hypertension; 2 for age ≥75 years; 1 for diabetes mellitus; 2 for stroke/transient ischemic attack/thromboembolic event; 1 for vascular disease (eg, prior myocardial infarction [MI], peripheral artery disease, or aortic plaque); 1 for age 65–74 years; and 1 for sex category (ie, female). The maximum score is 10.

The investigators evaluated the impact of the novel CHA2DS2-VASc risk score on outcomes among patients enrolled in the RE-LY trial. Primary outcome was stroke/systemic embolism; also assessed was net clinical benefit on stroke, systemic embolism, pulmonary embolism, MI, all-cause death and major bleeding. Relative risks (RR), 95% confidence intervals, and P-values for interaction were calculated.

Among the 18,113 patients, CHA2DS2-VASc scores were distributed as follows: risk score of 0–2 (n=4,042); 3 (n=5,365); 4 (n=4,374); and 5–9 (n=4,327). For dabigatran 110mg vs. warfarin, RR for the primary outcome was 0.81; for major bleeding, 0.06; for intracranial bleeding, 0.77; for vascular mortality, 0.24, and for net clinical benefit, 0.24. For dabigatran 150mg vs. warfarin, RR for the primary outcome was 0.60; for major bleeding, 0.003; for intracranial bleeding, 0.09; for vascular mortality, 0.14, and for net clinical benefit, 0.006. See Table.

Based on these results, Dr. Oldgren concludes that, “dabigatran 150mg has a favorable benefit risk profile compared with warfarin in patients with low to moderate CHA2DS2-VASc scores. Though it is difficult to interpret the net clinical benefit due to other confounding factors, dabigatran 110mg may be an alternative to [consider in] high-risk patients.”