Long-Term Outcomes With Cardiac Resynchronization Therapy in Patients With Mild Heart Failure With Moderate Renal Dysfunction.

BACKGROUND We aimed to determine the impact of renal function on long-term outcomes with cardiac resynchronization therapy with defibrillator among patients with mild heart failure (HF). METHODS AND RESULTS We stratified 1820 Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy patients by QRS morphology into those with and without left bundle-branch block. Subgroups within each QRS morphology category were created based on glomerular filtration rate (GFR): GFR <60 and ≥60 mL/min per 1.73 m(2). Primary end point was death; secondary end points were HF/death and HF events alone during long-term follow-up. Among 1274 left bundle-branch block patients, 413 (32%) presented with GFR <60 (mean, 48.1±8.3) mL/min per 1.73 m(2). Relative to the 861 (68%) patients with GFR ≥60 (mean, 79.6±16.0) mL/min per 1.73 m(2), low-GFR patients experienced higher risk of death (hazard ratio [HR], 2.09; 95% confidence interval [CI], 1.53-2.86; P<0.01) and HF/death (HR, 1.46; 95% CI, 1.17-1.82; P<0.01). In both GFR groups, cardiac resynchronization therapy with defibrillator was associated with reduction in death (GFR <60: HR, 0.66; 95% CI, 0.44-1.00; P=0.05 and GFR ≥60: HR, 0.68; 95% CI, 0.44-1.05; P=0.08) and HF/death (GFR <60: HR, 0.49; 95% CI, 0.36-0.67; P<0.01 and GFR ≥60: HR, 0.50; 95% CI, 0.38-0.66; P<0.01). In the low-GFR group, there was greater absolute reduction in risk of death (GFR <60: 14% and GFR ≥60: 6%) and HF/death (GFR <60: 25 and GFR ≥60: 15%). Among non-left bundle-branch block patients, low GFR predicted outcomes; however, no benefit from cardiac resynchronization therapy with defibrillator was observed. CONCLUSIONS In patients with mild HF, moderate renal dysfunction is associated with higher risk of death and HF during long-term follow-up. Patients with left bundle-branch block, regardless of baseline renal function, derive long-term benefit from cardiac resynchronization therapy with defibrillator, with greater absolute risk reduction in death and HF among those with moderate renal dysfunction. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00180271, NCT01294449, and NCT02060110.