Abstract
INTRODUCTION AND OBJECTIVES: Left bundle branch area pacing (LBBAP) has been associated with good clinical and echocardiographic outcomes and seems to be an alternative to conventional resynchronization therapy. However, data regarding functional outcomes are scarce. Our objective was to evaluate, using cardiopulmonary exercise testing (CET), changes in the functional capacity of patients with an indication for cardiac resynchronization therapy after LBBAP. METHODS: We conducted a prospective analysis of a cohort of patients with non-ischaemic dilated cardiomyopathy (NIDCM), left bundle branch block, QRS duration >130 ms, New York Heart Association functional class (NYHA-FC) II-IV, and left ventricular ejection fraction (LVEF) < 40% who underwent LBBAP. CET was performed before the procedure and after 6 months of follow-up. The primary endpoint was the change in peak oxygen uptake (VO(2)). The secondary endpoints included evaluation of clinical, echocardiographic, analytical, and other CET parameters. RESULTS: A total of 50 patients were included (44% female, 64 ± 11 years, LVEF 28 ± 7%). At baseline, peak VO(2) was 15.4 ± 4.9 ml/kg/min, and VO(2) at the first ventilatory threshold was 10.5 ± 2.9 ml/kg/min. At follow-up, we observed an increase of 3 ml/kg/min (95% CI 1.7-4.4; p < 0.01) and 2.6 ml/kg/min (95% CI 1.6-3.5; p < 0.01), respectively. Independent predictors of peak VO(2) at follow-up were baseline peak VO(2) and baseline QRS duration. Improvement was observed in the remaining CET, echocardiography, and clinical parameters. CONCLUSIONS: In symptomatic patients with non-ischaemic dilated cardiomyopathy, LVEF < 40%, and left bundle branch block, LBBAP was associated with an improvement in peak VO(2). Baseline QRS duration and baseline peak VO(2) were independent predictors of this parameter at follow-up.