Left bundle branch area pacing in patients with heart failure and left bundle branch block leads to marked left ventricular reverse remodeling and regression of ventricular dyssynchrony

Objective Conduction system pacing has emerged as a novel alternative to conventional biventricular pacing in patients with heart failure requiring cardiac resynchronization therapy (CRT). Purpose The aim of this study was to evaluate the rate of response and the degree of ventricular dyssynchrony in patients undergoing CRT using left bundle branch area pacing (LBBAP). Methods The study population consisted of consecutive patients with heart failure, left ventricular ejection fraction (LVEF) < 40 % and non-right bundle branch block morphology, who underwent successful CRT using LBBAP at a University and a Heart Center. Successful LBBAP implantation was defined as deep septal lead deployment, with QRS narrowing and a late r/R appearance in V1. Transthoracic echocardiography was performed before the procedure and at 6-month follow-up and was independently analyzed by two observers. Patients were classified as responders if left ventricular end-systolic volume (LVESV) decreased by >15%, and as super-responders if LVESV decreased by >30%. Ventricular dyssynchrony was assessed using ultra-high-frequency ECG (UHF-ECG) and QRS duration (QRSd) before implantation and immediately after the procedure. UHF-ECG parameter of ventricular dyssynchrony e-DYS was calculated as the maximal time delay between the earliest and latest ventricular activation across V1-V8 leads. Results A total of 100 patients with mean LVEF 31 ± 8 %, QRSd 172 ± 17 ms, and coronary artery disease present in 37 patients, were included in the analysis (additional baseline characteristics are shown in Figure 1). During 6-month follow-up, mean NYHA functional class improved from 2.3 ± 0.7 to 1.5 ± 0.7 (p<0.001). QRS duration shortened from 172 ± 17 ms to 154 ± 18 ms, and e-DYS decreased from 86 ± 25 ms to −15 ± 22 ms after implantation (p<0.001 for both). LVESV decreased from 122 ± 46 mL to 68 ± 32 mL, and LVEF improved from 31 ± 8 % to 46 ± 9% (p<0.001 for both) (Figure 2). Overall, 86 patients were classified as responders, including 71 super-responders. Nine patients had a reduction of LVESV by ≤ 15 %, and LVESV increased after six months of pacing in 5 patients. Conclusions Left bundle branch area pacing is an effective resynchronization strategy that results in regression of ventricular dyssynchrony, significant left ventricular reverse remodeling and clinical improvement. It is associated with an exceptionally high rate of response and super-response.