Mitral Annular Calcification in Obstructive Hypertrophic Cardiomyopathy: Prevalence and Outcomes

Background: The prevalence and clinical impact of mitral annular calcification (MAC) in patients with obstructive hypertrophic cardiomyopathy (HCM) are largely unknown. Methods: We reviewed 2113 HCM patients who underwent septal myectomy from January 2000 to April 2016. Preoperative and intraoperative echocardiograms along with operative notes were reviewed to identify MAC. Survival was estimated and compared using Kaplan-Meier analysis and the log-rank test. Cox regression analysis was used to identify factors independently associated with mortality. Results: MAC was identified in 390 (18.5%) patients. Older age, female sex, and presence of mitral valve leaflet calcification were strongly associated with higher odds of having MAC. Patients with MAC had higher resting left ventricular outflow tract gradients, were more likely to have worse mitral regurgitation preoperatively, and were more likely to undergo a concomitant mitral valve replacement (6% vs 1%; P < .001) compared with those without MAC. Postoperatively, patients with MAC had marginally higher residual mitral regurgitation (13% vs 8%). After a median follow-up of 6.95 (interquartile range, 3.7-12.1) years, survival of patients with MAC at 1, 5, and 10 years was 99%, 92%, and 69%, respectively. Adjusted analysis identified MAC as an independent predictor of poor survival (hazard ratio, 1.46; 95% confidence interval, 1.08-1.97; P = .014). Conclusions: MAC is a frequent finding in older patients with obstructive HCM, is more likely to be seen in females, and is associated with higher rates of concomitant mitral valve replacement. Despite the higher prevalence of comorbidities, MAC remained an independent predictor for overall mortality after septal myectomy.