Effect of Cardiac Resynchronization Therapy in Patients With Insulin-Treated Diabetes Mellitus

Diabetes mellitus (DM) modify outcome in patients with heart failure (HF). We aimed to analyze the risk for death, HF alone, combined end point HF/death, and ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with mild HF without DM and in those with DM, further stratified by the presence of insulin treatment. We determined whether cardiac resynchronization therapy with defibrillator (CRT-D) versus implantable cardioverter defibrillator improves clinical outcomes in these 3 subgroups. Cox proportional hazards regression models were used to analyze 1,278 patients with left bundle branch block in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy trial. Treatment with CRT-D versus implantable cardioverter defibrillator was associated with 76% risk reduction in all-cause mortality (hazard ratio 0.24; 95% confidence interval 0.08 to 0.74, p = 0.012) in subgroup of diabetic patients treated with insulin only (interaction p = 0.043). Significant risk reduction in HF alone, HF/death, and the VT/VF after CRT-D was observed across investigated groups and similar left ventricular reverse remodeling to CRT-D. In conclusion, patients with mild HF with DM treated with insulin derive significant risk reduction in mortality, in HF, and VT/VF after implantation of CRT-D. Diabetic patients not receiving insulin benefit from CRT-D by reduction of HF events.