Abstract 17167: Risk Stratification for Long-term Survival Benefit With Cardiac Resynchronization Therapy in Mild Heart Failure Patients

Abstract

Background: Cardiac resynchronization therapy (CRT) has been shown to reduce heart failure (HF) events or death in mild HF patients with left bundle branch block (LBBB) ECG pattern. However, risk stratification for long-term mortality benefit with CRT in this cohort is currently lacking. Methods: The study population comprised 1266 patients with LBBB enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT). A clinical risk score was developed using best-subset proportional hazards regression analysis in patients randomized to CRT with defibrillator (CRT-D) to predict survival benefit. Cox proportional hazards regression analysis was used to evaluate risk reduction of death by CRT-D versus an implantable cardioverter defibrillator (ICD)-only among the risk score groups. Results: We identified four clinical variables predicting outcome in CRT-D patients: age≥65, creatinine≥1.4 mg/dl, coronary artery bypass graft [CABG] in the patient history, and left ventricular ejection fraction [LVEF] < 26%. Five-year risk of mortality was 4% with no risk factor (low risk, n=357), 6% with 1 risk factor (n=500), 12% with 2 risk factors, and 27% with 3 risk factors (n=123); there were no patients with 4 risk factors. The mortality benefit from CRT-D vs. an ICD-only showed a U-shaped pattern with no significant benefit in patients with no risk factor (HR=0.77, CI 0.32-1.85, p=0.553), 46% reduction with 1 risk factor (HR=0.54, CI 0.32-0.89, p=0.017), 45% reduction with 2 risk factors (HR=0.55, CI 0.34-0.90, p=0.018), and no benefit with 3 risk factors (HR=0.77, CI 0.32-1.85, p=0.553). Conclusions: In MADIT-CRT, mild HF patients with LBBB with an intermediate mortality risk derived long-term survival benefit from CRT-D vs. an ICD-only. However, no survival benefit was observed in patients with low risk or a very-high risk.