Clinical outcome of cardiac resynchronization therapy in dilated-phase hypertrophic cardiomyopathy.

Backgrounds: Clinical trials have demonstrated that cardiac resynchronization therapy (CRT) is effective in patients with "non-ischemic cardiomyopathy". However, patients with dilated-phase hypertrophic cardiomyopathy (DHCM) have been generally excluded from such trials. We aimed to compare the clinical outcome of CRT in patients with DHCM, idiopathic dilated cardiomyopathy (IDCM), or ischemic cardiomyopathy (ICM).

Methods: A total of 312 consecutive patients (DHCM: = 16; IDCM: = 231; ICM: = 65) undergoing CRT in Fuwai hospital were studied respectively. Response to CRT was defined as reduction in left ventricular end-systolic volume (LVESV) ≥ 15% at 6-month follow-up.

Results: Compared with DHCM, IDCM was associated with a lower total mortality (HR: 0.35, 95% CI: 0.13-0.90), cardiac mortality (HR: 0.29; 95% CI: 0.11-0.77), and total mortality or heart failure (HF) hospitalizations (HR: 0.34, 95% CI: 0.17-0.69), independent of known confounders. Compared with DHCM, the total mortality, cardiac mortality and total mortality or HF hospitalizations favored ICM but were not statistically significant (HR: 0.59, 95% CI: 0.22-1.61; HR: 0.59, 95% CI: 0.21-1.63; HR: 0.54, 95% CI: 0.26-1.15; respectively). Response rate to CRT was lower in the DHCM group than the other two groups although the differences didn't reach statistical significance.

Conclusions: Compared with IDCM, DHCM was associated with a worse outcome after CRT. The clinical outcome of DHCM patients receiving CRT was similar to or even worse than that of ICM patients. These indicate that DHCM behaves very differently after CRT.