Comparison of Long-Term Survival Benefits With Cardiac Resynchronization Therapy in Patients With Mild Heart Failure With Versus Without Diabetes Mellitus (from the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy [MADIT-CRT]).

We have previously shown a reduction in HF events with cardiac resynchronization therapy with defibrillator (CRT-D) in patients with mild heart failure (HF) and diabetes mellitus (DM). It remains unknown whether HF remission in DM patients with CRT-D translates into reduced mortality. The effects of CRT-D versus an implantable cardioverter-defibrillator (ICD) alone to reduce long-term mortality were assessed in patients with left bundle branch block with DM (n = 386) and without DM (n = 982), enrolled in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT). We further subdivided DM patients by insulin and noninsulin therapy. Kaplan-Meier survival analyses and multivariate cox proportional hazards regression models were utilized. At the 7-year follow-up, CRT-D was associated with a lower mortality in DM patients compared with ICD alone (21% vs 42%, p = 0.02), similar to non-DM patients (16 vs 24%, p = 0.014). CRT-D was associated with a 41% reduction in the risk of long-term all-cause mortality in DM patients (hazard ratio [HR] 0.59, 95% confidence interval 0.36 to 0.96, p = 0.033) and a similar reduction in non-DM patients (HR 0.69, 95% confidence interval 0.48 to 0.99, p = 0.045, treatment-diabetes interaction p = 0.611). Among DM patients, mortality benefit was evident in insulin-treated patients only (HR 0.40, p = 0.030). Reductions in HF events were present in all groups. In the MADIT-CRT, patients with mild HF with DM derive significant long-term survival benefit from CRT-D, similar to those without DM. The mortality benefit from CRT-D within the DM subgroup seems to be confined to patients with insulin treated diabetes.