Evaluation of MADIT-II Risk Stratification Score Among Nationwide Registry of Heart Failure Patients With Primary Prevention Implantable Cardiac Defibrillators or Resynchronization Therapy Devices

Abstract

Current guidelines advocate prophylactic Implantable Cardioverter Defibrillator (ICD) for all symptomatic heart failure (HF) patients with low LVEF. Since many patients will never use their device, a score delineating subgroups with differential ICD benefit is crucial. We aimed to Evaluate MADIT II-based Risk Stratification Score (MRSS) feasibility to delineate ICD survival benefit among nationwide registry of HF patients with prophylactic ICDs. Accordingly, all Israeli HF patients with prophylactic ICD/CRTDs were categorized into MRSS-based risk-subgroups. Study endpoints included overall mortality, sustained ventricular arrhythmia (VA), and a competing risk of VA (potential preventable arrhythmic death, where ICD could benefit survival) versus non-arrhythmic death. Potential ICD survival benefit was estimated by the area between these cumulative incidence curves. Among 2,177 HF patients implanted prophylactic device, 189 patients (8.7%) had VA and 316 (14.5%) died during median Follow-up (F/U) of 2.9 years. MRSS risk-subgroups were significantly associated with overall mortality (p < 0.001) and weakly with VA (p 0.3). Competing risk analysis of VA versus non-arrhythmic death revealed significantly shorter duration (p < 0.001) and smaller magnitude of ICD survival benefit with increased risk subgroups, yielding estimated 76, 60, 38, and 0 life-days gained from prophylactic ICD implant during 5-year F/U for the MRSS low, intermediate, high, and very-high risk subgroups, respectively (p for trend< 0.05). In conclusion, MRSS use among nationwide registry of ischemic and non-ischemic cardiomyopathy patients, revealed subgroups with differing ICD survival benefit, suggesting it could help evaluate prophylactic ICD survival benefit.