The Association Between Biventricular Pacing and Cardiac Resynchronization Therapy-Defibrillator Efficacy When Compared With Implantable Cardioverter Defibrillator on Outcomes and Reverse Remodeling

Aug 21, 2014
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Authors:
Ruwald AC, Kutyifa V, Ruwald MH, et al.
Citation:
Eur Heart J 2014;Aug 11:[Epub ahead of print].
Summary By:
Thomas C. Crawford, MD, FACC

Study Questions:

What is the relationship between biventricular (BIV) pacing percentage thresholds and the efficacy of cardiac resynchronization therapy (CRT)?

Methods:

Using Kaplan–Meier plots, the authors estimated the threshold of BIV pacing percentage needed for CRT-D to be superior to implantable cardioverter-defibrillators (ICDs) on the endpoint of heart failure (HF) or death in 1,219 left bundle branch block (LBBB) patients in the MADIT-CRT trial.

Results:

In multivariable Cox analyses, no difference was seen in the risk of HF/death between ICD and CRT-D patients with BIV pacing ≤90% [hazard ratio (HR) = 0.78 (0.47–1.30), p = 0.3], and with increasing BIV pacing the risk of HF/death was decreased [CRT-D BIV 91–96% vs. ICD: HR = 0.63 (0.42–0.94), p = 0.024 and CRT-D BIV ≥97% vs. ICD: HR = 0.32 (0.23–0.44), p < 0.001]. The risk of death alone was reduced by 52% in CRT-D patients with BIV ≥97% (HR = 0.48, p < 0.016), when compared with ICD patients. Within the CRT-D group, for every 1 percentage point increase in BIV pacing, the risk of HF/death and death alone significantly decreased by 6% and 10%, respectively. Increasing BIV pacing percentage was associated with significant reductions in left ventricular volume.

Conclusions:

In patients with LBBB, who were in sinus rhythm at enrollment, BIV pacing exceeding 90% was associated with a benefit of CRT-D in HF/death when compared with ICD patients. Furthermore, BIV pacing ≥97% was associated with an even further reduction in HF/death, a significant 52% reduction in death alone, and increased reverse remodeling.

Perspective:

Based on the results of this and prior analyses, clinicians should make every effort to maximize BIV pacing, preferably to near 100%.

Keywords: Cardiac Pacing, Artificial, Heart Failure, Bundle-Branch Block, Defibrillators, Implantable, Cardiac Resynchronization Therapy


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