Pakistan Journal of Pharmaceutical Sciences

Abstract: Background: Left bundle branch area pacing (LBBaP) has emerged as a physiological pacing strategy for cardiac resynchronization therapy in patients with heart failure (HF) and left bundle branch block (LBBB). However, evidence comparing different pharmacological regimens following LBBaP implantation remains limited. Objectives: To compare the effects of sacubitril/valsartan and enalapril on QRS duration and cardiac function in HF patients undergoing LBBaP. Methods: This retrospective cohort study included 106 patients with HF and LBBB who underwent successful LBBaP implantation at a single center between January 2022 and December 2023. According to the postoperative pharmacotherapy protocol, patients were divided into two groups: a control group receiving enalapril (n = 52) and an observation group receiving sacubitril/valsartan (n = 54). After six months of follow-up, QRS duration and amplitude, echocardiographic parameters (left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD)), functional capacity assessed by the 6-minute walk distance (6MWD), serum biomarkers (N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI)) and major adverse cardiovascular events (MACE) were compared between the two groups. Results: Both groups showed improvements in electrophysiological and cardiac functional parameters after treatment. Compared with the enalapril group, patients receiving sacubitril/valsartan demonstrated significantly shorter QRS duration (125.45 ± 9.79 ms vs 150.23 ± 3.33 ms, P < 0.001), higher LVEF (57.03 ± 2.49% vs 50.29 ± 2.18%, P < 0.001) and smaller LVESD and LVEDD (all P < 0.001). In addition, the sacubitril/valsartan group showed greater improvement in exercise capacity (6MWD: 370.25 ± 17.64 m vs 349.51 ± 17.45 m, P < 0.001) and lower levels of NT-proBNP and cTnI. The incidence of MACE during the 6-month follow-up was also lower in this group (11.11% vs 26.92%, P = 0.038). Conclusion: Among HF patients with LBBB undergoing LBBaP implantation, treatment with sacubitril/valsartan was associated with greater short-term improvements in QRS duration, cardiac function and exercise capacity compared with enalapril. Larger prospective studies with longer follow-up are required to further evaluate long-term clinical outcomes.