Effect of hypertrophic cardiomyopathy on the prediction of thromboembolism in patients with nonvalvular atrial fibrillation.

BACKGROUND:Anticoagulation is recommended for hypertrophic cardiomyopathy (HCM) with nonvalvular atrial fibrillation (NVAF) according to European and American guidelines. However, it is unclear whether HCM is a risk factor for thromboembolism in NVAF in Japan, and the management for NVAF with HCM is not established. OBJECTIVE:We studied the impact of concomitant HCM on predicting thromboembolism in NVAF. METHODS:We retrospectively studied consecutive 2374 Japanese patients with NVAF (1682 men, 70.9%; mean age 71±10 years). Clinical factors were evaluated using the Cox proportional hazards model. We also investigated whether adding HCM to CHADS2 or CHA2DS2-VASc score improved the prediction of thromboembolism. RESULTS:Thromboembolism was observed in 122 patients (5.1%) during the median follow-up of 2.4 years (interquartile range 2.0-3.2 years). The Cox proportional hazards model showed that HCM was significantly associated with thromboembolism after adjustment for CHADS2 or CHA2DS2-VASc score (hazard ratio 3.41; 95% confidence interval [CI] 1.98-5.73; P<.0001 and hazard ratio 3.38; 95% CI 1.97-5.64; P<.0001, respectively). NVAF with HCM had significantly higher thromboembolism rates, even in those with a CHADS2 or CHA2DS2-VASc score of 1 or 0-1, respectively. Based on the comparison of C-statistics, the addition of HCM to CHADS2 or CHA2DS2-VASc score significantly improved the prediction of thromboembolism (C-statistics 0.75 vs 0.71; P=.003 and C-statistics 0.77 vs 0.71; P=.0001, respectively). CONCLUSION:HCM is an independent risk factor for thromboembolism in patients with NVAF. A markedly high incidence of thromboembolism is observed in NVAF patients with HCM with CHA2DS2-VASc score of both ≥2 and 0-1, and anticoagulation therapy is recommended for them.