Trial of Left Bundle Branch vs. Biventricular Pacing for CRT
- Among 40 patients with nonischemic cardiomyopathy and left bundle branch block (LBBB) randomized to LBBP-CRT vs. BiVP-CRT, LBBP-CRT resulted in a greater improvement of the LVEF, and greater reductions in LV end-systolic volume and NT-proBNP.
- Randomized trials are needed to compare the long-term effects of LBBP and BiVP on functional status and survival in patients with heart failure and LBBB.
What is the efficacy of left bundle branch pacing cardiac resynchronization therapy (LBBP-CRT) with biventricular pacing cardiac resynchronization therapy (BiVP-CRT) in patients with heart failure and reduced left ventricular ejection fraction (LVEF)?
LBBP-RESYNC (Left Bundle Branch Pacing Versus Biventricular Pacing for Cardiac Resynchronization Therapy) was a prospective, randomized pilot trial of patients with nonischemic cardiomyopathy and left bundle branch block (LBBB) with 6-month preplanned follow-up. The primary endpoint was the difference in LVEF improvement. The secondary endpoints included changes in echocardiographic measurements, N-terminal pro–B-type natriuretic peptide (NT-proBNP), New York Heart Association (NYHA) functional class, 6-minute walk distance, QRS duration, and CRT response.
There were 40 patients (mean age, 64 years; LVEF 30%). Crossovers occurred in 10% of LBBP-CRT and 20% of BiVP-CRT. All patients completed follow-up. Intention-to-treat analysis showed significantly higher LVEF improvement at 6 months after LBBP-CRT than BiVP-CRT (mean difference, 5.6%; p = 0.039). LBBP-CRT also had greater reductions in LV end-systolic volume and NT-proBNP, and comparable changes in NYHA functional class, 6-minute walk distance, QRS duration, and rates of CRT response compared with BiVP-CRT.
The investigators concluded that LBBP-CRT demonstrated greater LVEF improvement than BiVP-CRT in heart failure patients with nonischemic cardiomyopathy and LBBB.
CRT in patients with LBBB is associated with improved functioning and reduced mortality. Unfortunately, there is a significant number of nonresponders, and not an insignificant failure rate of implantation due to anatomic limitations. His-bundle pacing has provided an alternative to traditional biventricular pacing. While achieving more physiological pacing in many, His-bundle pacing itself has had a relatively high failure rate and suboptimal long-term performance. Several prior observational studies have shown the feasibility and utility of LBBP, but the present study is the first to provide a prospective, randomized evaluation. Direct LBBP offers the possibility of pacing distal to the site of LBBB, as the electrode penetrates the interventricular septum often achieving a narrower paced QRS with low stable pacing thresholds. Randomized trials are needed to compare the long-term effects of LBBP and BiVP on functional status and survival in patients with heart failure and LBBB. Different approaches may be required depending on the location of the block and the underlying cardiomyopathic process before widespread adoption, but at this time, LBBP is at least offering an attractive alternative to unsuccessful or suboptimal BiVP.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Echocardiography/Ultrasound
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiac Resynchronization Therapy, Cardiomyopathies, Echocardiography, Heart Failure, Natriuretic Peptide, Brain, Pacemaker, Artificial, Stroke Volume, Ventricular Function, Left
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