Long-term outcomes of patients with apical hypertrophic cardiomyopathy: incorporation of a novel risk score

Abstract Background Apical hypertrophic cardiomyopathy (aHCM) is a subtype of HCM characterized by left ventricular hypertrophy predominantly in the apex. There is still limited data on factors associated with adverse outcomes in patients with aHCM. Objectives To a) describe the characteristics and b) develop a novel risk score associated with outcomes in aHCM patients. Methods A total of 462 patients (mean age 58±15 years, 68% male and 70% white) diagnosed with aHCM based on clinical, echocardiographic, and cardiac magnetic resonance (CMR) evaluation were included. The primary endpoint was all-cause death or aborted sudden cardiac death. Using the cox regression analysis, variables showing potential association with the composite endpoint were considered to develop an aHCM specific risk score. Results On echocardiography, the mean LV ejection fraction (LVEF) was 64±8%, and the mean LV mass was 223±72 g. A baseline CMR was performed in 246 (53%) patients, with delayed gadolinium enhancement in 170 (71%) patients with a mean percentage of 5±7%. Patients were followed-up for a mean of 68 months (range 1-248), with composite events occurring in 80 (17%) patients (death in 62 [13%] patients). Univariate Cox regression analysis identified age hazard ratio (HR) 1.06 (95% Confidence Interval or CI 1.04-1.08; p< 0.001), apical aneurysm HR 2.32 (95% CI 1.24-4.34 p=0.008), lower LVEF HR 0.96 (95% CI 0.94-0.99 p=0.002), higher right ventricular systolic pressure (RVSP) HR 1.04 (95% CI 1.02-1.06 p< 0.001), New York Heart Association Class IV HR 11.69 (95% CI 3.59-38.08 p< 0.001) and the presence of Atrial fibrillation HR 1.77 (95% CI 1.14-2.76 p=0.012). An aHCM specific risk score was subsequently created (Figure 1), with good discrimination (c-statistic=0.75) and good calibration with expected to observed ratio of 1.02 and a calibration slope of 0.91 (p-value for difference between expected and observed probabilities =0.22). The risk score ranges between 0 and 8 points, with higher score associated with a higher rate of composite events (Figure 2). Conclusion We developed a novel risk score which demonstrated incremental prognostic value for hard events in aHCM patients.Risk prediction modelKaplan Meier event-free survival curves