Prognostic value of red blood cell distribution width for mortality in patients with hypertrophic cardiomyopathy

Background: Red blood cell distribution width (RDW) has emerged as a useful indicator for adverse outcomes in several cardiovascular diseases. The relation between RDW and the prognosis of hypertrophic cardiomyopathy (HCM) remains to be evaluated. We examined the relation between RDW and all-cause mortality and HCMrelated death in a population of adult HCM patients. Methods: We performed clinical evaluation in 414 consecutive adult HCM patients (median age, 57.5 years; male, 54.8%). Results: During a median follow-up of 3.7 years, all-cause mortality and HCM-related death occurred in 75 (18.1%) and 50 (12.1%) patients, respectively. Based on the tertiles of baseline RDW, mortality increased with higher tertile. With the tertile 1 as reference, adjusted all-cause mortality hazard ratios (HRs) were 3.9 for the tertile 2 (95% confidence interval [CI]: 1.5-10.3) and 3.1 for the tertile 3 (95% CI: 1.1-8.2). Adjusted HCMrelated death HRs were higher in the tertile 2 (HR: 5.5; 95% CI: 1.2-24.4) and tertile 3 (HR: 6.6; 95% CI: 1.5-29.0) compared with the tertile 1. Further smooth curve fitting exhibited a saturation effect after adjusting for confounders, and there were a two-stage change and an inflection point. Two-piecewise Cox model suggested mortality significantly increased with RDW level up to the inflection point (about 14.0% for both all-cause mortality and HCM-related death), and RDW was not associated with mortality after the point. Conclusion: In adult HCM patients, we found increased RDW was a significant risk predictor for all-cause mortality and HCM-related death, and a saturation effect was observed.