Background: Recent European guidelines recommended the CHA2DS2-VASc score for thromboembolic and the HAS-BLED score for bleeding risk stratifications. We validated these scores in 7,384 Japanese patients with nonvalvular atrial fibrillation (NVAF) enrolled in the J-RHYTHM Registry.
Methods and results: Of the study cohort, 6,387 patients taking warfarin and the other 997 not taking warfarin were prospectively examined for 2 years. Thromboembolic and major bleeding risks were stratified by modified CHA2DS2-VASc (mCHA2DS2-VASc) and HAS-BLED (mHAS-BLED) scores, respectively. Of the patients with mCHA2DS2-VASc score 0, 1, and ≥2, thromboembolism occurred in 2/141 (0.7%/year), 4/233 (0.9%/year), and 24/623 (1.9%/year), respectively, in the non-warfarin group, and in 1/346 (0.1%/year, P=0.19 vs. non-warfarin), 4/912 (0.2%/year, P=0.05), and 92/5,129 (0.9%/year, P=0.0005), respectively, in the warfarin group. When female sex was excluded from the score, thromboembolism occurred in 2/180 patients (0.6%/year), 5/245 (1.0%/year), and 23/572 (1.6%/year), respectively, in the non-warfarin group, and in 1/422 (0.1%/year, P=0.20 vs. non-warfarin), 5/1,096 (0.2%/year, P=0.02), and 91/4,869 (0.9%/year, P=0.0005), respectively, in the warfarin group. Patients with mHAS-BLED scores ≥3 were at high risk for major bleeding irrespective of warfarin treatment (1.3 and 2.6%/year in the non-warfarin and warfarin groups, respectively).
Conclusions: In Japanese NVAF patients, the mCHA2DS2-VASc score is useful for identifying patients at truly low risk of thromboembolism. Female sex may be excluded as a risk from the score. mHAS-BLED score ≥3 is useful for identifying patients at high risk of major bleeding.