Effect of cardiac resynchronization therapy in patients with diabetes randomized in EchoCRT.

Aims: As patients with heart failure (HF) and concomitant diabetes carry a poor prognosis, this post-hoc subgroup analysis aimed to compare the outcomes of patients with and without diabetes randomized in the Echocardiography Guided Cardiac Resynchronization Therapy (EchoCRT) study.
Methods and Results: EchoCRT randomized patients with a QRS duration <130 ms and echocardiographic evidence of left ventricular dyssynchrony to CRT turned on (CRT=ON) vs. off (CRT=OFF) following device implantation. At study entry, 328 patients (40.5%) had diabetes. The primary outcome (all-cause death or first hospitalization for worsening HF) occurred more frequently in patients with than without diabetes (32.6% vs. 23%, P = 0.003). A significant treatment interaction was observed for the primary outcome indicating a higher risk for CRT=ON vs. CRT-OFF in patients without [26.5% vs. 19.8%, hazard ratio (HR) 1.58, 95% confidence interval (CI) 1.08-2.31] vs. with diabetes (31.4% vs. 34%; HR 0.86, 95% CI 0.58-1.27; P for interaction 0.041). This effect was mainly driven by a lower rate in HF hospitalizations, but was only of borderline significance after multivariate adjustment (P = 0.063). The most pronounced effect was observed in patients with non-ischaemic cardiomyopathy, where a significantly reduced risk of reaching the primary endpoint for CRT=ON vs. CRT-OFF was observed in patients with (HR 0.27, P = 0.003) vs. patients without diabetes (HR 1.79, P = 0.038; P for interaction 0.005). No treatment interaction by diabetes diagnosis was found for mortality endpoints.
Conclusion: In EchoCRT, HF patients with a narrow QRS complex and coexisting diabetes demonstrated a signal for less harm caused by CRT compared with patients without diabetes, which was driven by differences in hospitalizations owing to HF.
(© 2016 The Authors. European Journal of Heart Failure © 2016 European Society of Cardiology.)