The initial experience of left bundle branch area pacing in patients with hypertrophic cardiomyopathy.

Purpose: Whether left bundle branch area pacing (LBBAP) could be achieved in patients with hypertrophic cardiomyopathy (HCM) requiring ventricular pacing remains unknown. The present study aimed to investigate the feasibility and effect of LBBAP in HCM.

Methods: Patients with HCM who underwent LBBAP were recruited from November 2018 to September 2021. Clinical characteristics, echocardiographic, and pacing parameters were prospectively collected at baseline and during follow-up.

Results: Eleven consecutive HCM patients who attempted LBBAP were included (mean age 64.0 ± 8.7 years, female 45.5%, mean interventricular septum 16.7 mm). The success rate of LBBAP was 36.4% (4/11) and the reason for failed LBBAP in other seven HCM patients was the inability to screw the lead into the deep septum or capture the left bundle branch. Patients with successful LBBAP had significantly narrower QRS duration than those with failed cases (118.0 ± 3.7 ms vs. 140.9 ± 9.4 ms, p = .01) while the capture thresholds, sensing amplitudes, and pacing impedances were similar. Successful cases presented with less positive late gadolinium enhancement (25.0% vs. 71.4%, p = .02) and thinner interventricular septum thickness (14.5 ± 1.0 mm vs. 18.0 ± 2.5 mm, p = .02) compared with failed cases. Pacing parameters remained stable and no procedure-related complications occurred during a mean follow-up of 8.9 ± 7.3 months.

Conclusion: LBBAP may be successfully achieved in less than half of HCM patients due to thick interventricular septum and heavy burden of myocardial fibrosis. Pacing strategies should be cautiously considered in patients with HCM.