Abstract 12677: Long-Term Survival of Patients With Left Bundle Branch Block who are Clinical or Echocardiographic Hypo-Responders to Cardiac Resynchronization Therapy

Abstract

Introduction: Guidelines support cardiac resynchronization therapy with a defibrillator (CRT-D) in heart failure (HF) patients with left bundle branch block (LBBB). However, not all patients demonstrate clinical or echocardiographic (ECHO) response to CRT-D. We aimed to compare the long-term outcomes of clinical hypo-responders and ECHO hypo-responders with LBBB who were enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT). Methods: Five-hundred thirty-four patients with LBBB in the CRT-D arm were followed for 5.6 years (median). Clinical hypo-response was defined as presence of defibrillator treated ventricular arrhythmia or HF event in the first year after CRT-D implantation. ECHO hypo-response was defined as less than or equal to 35% reduction (median) in left ventricular end-systolic volume (LVESV) 1 year after CRT-D implantation; we also tested 15% and 25% reduction in LVESV. Results: Clinical and ECHO response was observed in 246 (46%) patients. Two-hundred twenty-six (42%) patients were ECHO hypo-responders and 62 (12%) patients were clinical hypo-responders. Fifty (9%) patients died during long-term follow-up. ECHO hypo-responders had an increased risk of all-cause mortality compared to clinical + ECHO responders (hazard ratio [HR] 3.02, 95% CI 1.45-6.31, p=0.003). Clinical hypo-responders had an increased risk of mortality compared to clinical + ECHO responders (HR 3.67, 95% CI 1.45-9.33, p=0.006), but not compared to ECHO hypo-responders. There was no significant difference between outcomes for clinical hypo-responders and ECHO hypo-responders when using an ECHO cutoff of 15% or 25% reduction in LVESV. Conclusion: During long-term follow-up, heart failure patients with LBBB who have clinical or echocardiographic hypo-response to CRT-D have comparable increased risk of mortality relative to patients who demonstrate good clinical and echocardiographic responses.