Left Bundle Branch Pacing for Cardiac Resynchronization Therapy: Nonrandomized On-Treatment Comparison With His Bundle Pacing and Biventricular Pacing

Background: Left bundle branch pacing (LBBP) is a novel method for delivering cardiac resynchronization therapy (CRT). We compared on-treatment outcomes with His bundle pacing (HBP) and biventricular pacing (BVP) in this nonrandomized observational study. Methods: Consecutive patients with left-ventricular ejection fraction (LVEF) <= 40% and typical left bundle branch block (LBBB) referred for CRT received BVP, HBP, or LBBP. QRS duration, pacing threshold, LVEF, and New York Heart Association (NYHA) class were assessed. Results: One hundred thirty-seven patients were recruited: 49 HBP, 32 LBBP, and 54 BVP; 2 did not receive CRT. The majority of patients had nonischemic cardiomyopathy. Mean paced QRS duration was 100.7 +/- 15.3 ms, 110.8 +/- 11.1 ms, and 135.4 +/- 20.2 ms during HBP, LBBP, and BVP, respectively. HBP and LBBP demonstrated a similar absolute increase (Delta) in LVEF (thorn23.9% vs thorn24%, P = 0.977) and rate of normalized final LVEF (74.4% vs 70.0%, P = 0.881) at 1-year followup. This was significantly higher than in the BVP group (D LVEF thorn16.7% and 44.9% rate of normalized final LVEF, P < 0.005). HBP and LBBP also demonstrated greater improvements in NYHA class compared with BVP. LBBP was associated with higher R-wave amplitude (11.2 +/- 5.1 mV vs 3.8 +/- 1.9 mV, P < 0.001) and lower pacing threshold (0.49 +/- 0.13 V/0.5 ms vs 1.35 +/- 0.73 V/0.5 ms, P < 0.001) compared with HBP. Conclusion: LBBP appears to be a promising method for delivering CRT. We observed similar improvements in symptoms and LV function with LBBP and HBP. These improvements were significantly greater than those seen in patients treated with BVP in this nonrandomized study. These promising findings justify further investigation with randomized trials.

Automated summary

Left bundle branch pacing (LBBP) appears to be a promising method for delivering cardiac resynchronization therapy (CRT), showing similar improvements in symptoms and left ventricular function compared with His bundle pacing (HBP) but more significant than biventricular pacing (BVP).