Sex-Specific Outcomes of LBBAP vs. Biventricular Pacing

Quick Takes

  • Women obtain significantly greater reductions in the combined endpoint of death and HF with left bundle branch area pacing compared to biventricular pacing among patients requiring pacing, as compared to men.
  • Sex-specific echocardiographic outcomes were better in women than men.

Study Questions:

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has been associated with greater clinical improvement. Does the mode of CRT as in left bundle branch area pacing (LBBAP) confer greater benefit in outcomes related to heart failure (HF), as compared to BVP among the sexes?


In a large, international, multicenter cohort of patients undergoing CRT with BVP and LBBAP, a detailed sex-specific analysis was performed in 1,778 patients (575 female and 1,203 male). The study included patients who underwent CRT with class I and class II indications (New York Heart Association class II-IV symptoms and left ventricular ejection fraction <35%, QRS >130 ms, or frequent pacing). All patients underwent either BVP or LBBAP based on operator and clinical practice at the institution. The patients had baseline demographics, medications, and electrocardiographic and echocardiographic findings recorded and were then followed at regular intervals in the clinic and remote monitoring. The primary outcome was a combined endpoint of all-cause mortality or first episode of HF and unplanned inpatient hospitalization. Comparisons between the two groups were made by chi-square test or Fisher exact test and independent sample t-test or Mann-Whitney U-test as appropriate.


Women participants were more likely to have nonischemic cardiomyopathy and left bundle branch block (LBBB) and less likely to have hypertension, diabetes, or coronary artery disease than men participants. Overall, women have a better result with LBBAP compared to BVP with a significant 36% reduction in death or HF hospitalization (hazard ratio [HR], 0.64; 95% confidence interval [CI], 0.24-0.69; p < 0.01). Women also had great reduction in death and HF hospitalizations among those with nonischemic cardiomyopathy (HR, 0.45; 95% CI, 0.26-0.79; p < 0.01) and LBBB (HR, 0.49; 95% CI, 0.27-0.87; p < 0.01). Overall, a greater improvement in the ejection fraction was seen in LBBAP compared to BVP among the overall population of women, as well as in women with nonischemic cardiomyopathy, LBBB, and QRS >150 ms.


The findings from this multicenter, retrospective, observational study show that women undergoing LBBAP have an improved combined endpoint of all-cause mortality and HF hospitalizations when compared to BVP than men.


This study adds to the growing evidence that women do better and respond better to LBBB pacing than men when looking exclusively at nonischemic cardiomyopathy. The recently published LBBAP collaborative study I-CLAS (International Collaborative LBBAP Study) demonstrated that LBBAP improved clinical outcomes among patients undergoing CRT compared to BVP as well. This is a substudy and reports sex-specific outcomes between the subgroups.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices

Keywords: Cardiac Pacing, Artificial, Cardiac Resynchronization Therapy, Cardiomyopathies

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