Performance and validation of R-CHA₂DS₂VASc score for thromboembolism in patients with hypertrophic cardiomyopathy

Objective: To validate the modified R-CHA₂DS₂VASc score as a predictor of thromboembolism in HCM patients.

Methods: A total of 446 HCM patients were enrolled in our study, thirty-one (6.95%) patients experienced thromboembolic events during the follow-up time of 1786.7 person-years. The association between R-CHA₂DS₂VASc score and risk of thromboembolism was assessed by Cox's proportional hazard analysis. The discriminatory power of R-CHA₂DS₂VASc score for thromboembolism prediction was assessed by Harrell's C-statistic and validated internally by bootstrapping methods. Calibration plot was plotted by observed versus expected probabilities of thromboembolism.

Results: The R-CHA₂DS₂VASc score was well calibrated with 0.84 thromboembolic events per 100 person-years in the predefined low risk (R-CHA₂DS₂VASc score ≤2) group, 1.84 in the low to moderate risk (R-CHA₂DS₂VASc score 3-4) group, 4.67 in the moderate to high risk (R-CHA₂DS₂VASc score 5-7) group, and 17.54 in the high risk (R-CHA₂DS₂VASc score ≥8) group. Hazard ratios for thromboembolism were 2.88 (95%CI: 1.06-7.82, P=0.038) for low to moderate versus low risk group, 5.30 (95%CI: 2.14-13.12, P=0.0003) for moderate to high versus low risk group, and 16.57 5.30 (95%CI: 4.96-55.33, P<0.0001) for high versus low risk group after adjusting left atria size. The Harrell's C statistic was 0.7737 (95% CI: 0.65-0.89) for R-CHA₂DS₂VASc score.

Conclusion: The R-CHA₂DS₂VASc score has shown good calibration and discriminative power in the prediction of thromboembolism for HCM patients. It should be considered as a potential decision support tool for HCM patients during clinical practice.