Cardiac resynchronization therapy in patients with end-stage hypertrophic cardiomyopathy.

Abstract

A dilated/end-stage phase of hypertrophic cardiomyopathy (HCM) is rare but well-recognized. The role for cardiac resynchronization therapy (CRT) in this subset of patients remains unexplored. We aimed to clarify the impact of bi-ventricular pacing CRT in dilated/end-stage HCM. The Mayo Clinic HCM database was interrogated to identify patients with ejection fraction (EF) <50% and CRT. Control subjects were identified in 1:1 manner. Clinical outcomes were determined. Of 2073 patients with HCM, 9 (8 male) had EF <50% and received CRT. The average age at CRT-D implant was 44.8 ± 14.8 years, an average of 17.3 ± 10.3 years after HCM diagnosis. The indication for CRT was based on New York Heart Association class ≥II symptoms (mean 2.7 ± 0.4) and EF <50% in all patients (EF 34.7 ± 7.1% at implant), with electrocardiographic evidence of abnormal ventricular conduction. At 6-month, 12-month, and long-term follow-up, EF was 39.9 ± 8.4%, 37.9 ± 9.8%, and 33.3 ± 7.6%, respectively (P > 0.05 for all). There was no difference in the combined end-point of left ventricular assist device (LVAD), cardiac transplant, or death between groups (P = 0.90). At last follow-up [mean duration 12.9 ± 8.3 (median 10.7) years], 8 (89%) in the CRT group were alive. Three and 2 patients underwent LVAD implantation and cardiac heart transplantation, respectively, 15.0 ± 10.1 years from HCM diagnosis and 2.6 ± 0.9 years from CRT implant. In the control group, 4 (44.4%) patients were alive at last follow-up [mean duration 12.0 ± 7.1 (median 12.7) years]. One patient each had LVAD and cardiac transplant. CRT in patients with dilated/end-stage HCM does not appear to confer a salutary effect on ventricular function. In medium-term follow-up, however, left ventricular function did not appear to deteriorate further, yet advanced heart failure therapy was common in this group.