Effectiveness of cardiac resynchronization therapy in diabetic patients with ischemic and nonischemic cardiomyopathy.

BACKGROUND: Diabetes mellitus (DM) increases the risk for the development of both ischemic and nonischemic cardiomyopathy. We aimed to identify differences in response to cardiac resynchronization therapy with a defibrillator (CRT-D) among DM patients with ischemic or nonischemic cardiomyopathy.
METHODS: Cox proportional hazards regression modeling was used to assess clinical response to CRT-D (defined as CRT-D vs. defibrillator-only reduction in the risk of heart failure [HF] or death) and echocardiographic response (defined as percent reduction in left ventricular end diastolic and systolic volume [LVEDV and LVESV, respectively] at 12 month of follow-up compared with baseline values) among 552 diabetic patients with ischemic (n = 367) or nonischemic (n = 185) cardiomyopathy enrolled in MADIT-CRT.
RESULTS: The clinical benefit of CRT-D was more pronounced among nonischemic patients (HR = 0.30 [P < 0.001] than among ischemic patients (HR = 0.59 [P = 0.004]; P for interaction = 0.10). Nonischemic patients also experienced significantly greater reductions in LVESV and LVEDV at 12 months with CRT-D compared with ischemic patients (P < 0.001 for both). Subgroup analysis showed that the most pronounced reduction in HF or death with CRT-D therapy occurred in nonischemic patients who were women (83% risk-reduction [P < 0.001]), had a lower BMI (<30/kg/m(2) : 79% risk-reduction [P < 0.001]), or had left bundle branch block at enrollment (82% risk-reduction [P < 0.001]).
CONCLUSIONS: The present study shows that treatment with CRT-D in at-risk cardiac patients with DM is associated with substantial reductions in the risk of HF or death and improvement in cardiac remodeling in those with ischemic and nonischemic cardiomyopathy, with a more pronounced benefit in patients with nonischemic disease.