Abstract 15114: Paradoxical Association of Ventricular Tachyarrhythmias and All-Cause Mortality in Patients With Renal Impairment: a MADIT-CRT Substudy

Abstract

Background: The risk of ventricular tachyarrhythmias (VTAs) in mild heart failure patients with renal dysfunction receiving cardiac resynchronization therapy plus an implantable cardioverter-defibrillator (CRT-ICD) or an ICD alone is not well understood. Hypothesis: We assessed the hypothesis that baseline renal function affects risk of VTAs and all-cause mortality as well as benefit derived from CRT-ICD during in-trial follow-up. Methods: We evaluated the impact of renal function in 1274 patients with mild heart failure and left-bundle branch block enrolled in MADIT-CRT. Patients with BUN>70 mg/dl or creatinine>3.0 mg/dl were excluded from the trial. Two subgroups were created based on the estimated glomerular filtration rate (GFR): GFR<60 and GFR≥60 ml/min/1.73 m2. Patients were studied over 3.3 years of follow-up for endpoints of ventricular tachycardia ≥200 beats per minute or ventricular fibrillation (fast VT/VF) and all-cause mortality. Results: The 413 patients with GFR<60 ml/min/1.73 m2 (mean 48.1±8.3) experienced lower risk of fast VT/VF (HR: 0.63, 95% CI: 0.44-0.90, p=0.012) but increased risk of death (HR: 2.43, 95% CI: 1.67-3.57, p<0.001), relative to those in the GFR≥60 group (mean 79.6±16.0) [Figure]. For both, CRT-ICD relative to ICD-only treatment was associated with lower likelihood of fast VT/VF (GFR<60: HR=0.46, 95% CI: 0.24-0.86, p=0.016; GFR≥60: HR=0.54, 95% CI: 0.38-0.76, p<0.001) without a significant effect on death (GFR<60: HR=0.62, 95% CI: 0.38-1.04, p=0.065; GFR≥60: HR=0.78, 95% CI: 0.45-1.36, p=0.379). There was no significant treatment interaction for the endpoints (p>0.10). Conclusion: In conclusion, in mild heart failure patients, moderate renal dysfunction is associated with lower risk of VTAs but greater risk of all-cause mortality relative to mildly impaired-to-normal renal function. In both groups, similar benefit from CRT-ICD was found in reducing risk of VTAs.