Abstract 11330: The Influence of Percent Biventricular Pacing on CRT Efficacy Compared to ICD Therapy on Outcomes and Reverse Remodeling
Background: Previous studies have found optimal benefit of cardiac resynchronization therapy (CRT) with biventricular (BIV) pacing above 92%. However no study has investigated the threshold of effective CRT pacing when compared to an implantable cardioverter defibrillator (ICD).
Aim: Using the MADIT-CRT population, we investigated the threshold of percent BIV pacing where CRT-D is superior to ICD in patients with left bundle branch block (LBBB).
Method: We evaluated 1011 ICD and CRT-D patients with LBBB, having excluded any patient with a device change during follow-up (N=236) and CRT-D patients with either missing BIV pacing data (N=24) or who were not in DDD pacing mode (N=10). Using Kaplan-Meier plots and multivariate Cox analyses, we estimated the threshold of BIV pacing needed for CRT-D to be superior to ICD on the end point of heart failure (HF) or death. We created 4 groups: ICD (N=380), CRT-D BIV ≤ 96% (N=174), CRT-D BIV 97-99% (N=288) and CRT-D BIV=100% (N=169).
Results: As shown in Figure 1, BIV pacing ≤ 96% did not improve clinical outcome in patients with CRT-D as compared to those with ICD. Higher BIV pacing percentage was associated with significantly decreased risk of HF/death. When compared to ICD patients, multivariate analysis revealed a 45% and 80% reduction in HF/death in patients with CRT-D BIV 97-99% (HR=0.55 [0.38-0.82], p=0.003) and CRT-D BIV=100% (HR=0.20 [0.09-0.44], p<0.001), respectively. No difference was found between CRT-D BIV ≤ 96% and ICD patients (HR=0.92 [0.62-1.36], p=0.66).
Increasing BIV pacing percentage was associated with significant reductions in left ventricular end systolic volumes at one year (% reductions: 31.4±14.3, 35.3±13.8 and 40.0±14.2 for increasing BIV pacing group; overall p<0.001; between groups p<0.01).
Conclusion: In patients with LBBB increasing BIV pacing percentage is associated with increased reverse remodeling. BIV pacing should exceed 96 % in order for CRT-D to be superior to ICD therapy in reducing HF/death.
- © 2013 by American Heart Association, Inc.