Introduction: Right ventricular apical (RVA) pacing, commonly used in complete atrioventricular block (AVB), frequently causes electrical and mechanical myocardial dyssynchrony. This can lead to left ventricular (LV) remodeling and heightened heart failure (HF) risk. In contrast, left bundle branch area pacing (LBBAP) leverages the heart's native conduction system, enabling more physiological ventricular activation, synchronous contraction, stable hemodynamics, and reduced adverse clinical outcomes.

Objective: To perform a comparative analysis of clinical and functional parameters, clinical outcomes, and adverse cardiovascular event rates in AVB patients during mid-term follow-up after LBBAP versus RVA pacing.

Materials and Methods: This prospective study enrolled 74 patients (mean age 72.8±11.0 years, 52% men) with complete AVB and baseline LV ejection fraction (LVEF) ≥50%. Patients were randomized 1:1 into Group 1 (LBBAP, n=37) and Group 2 (apical RVA, n=37), all with ventricular pacing burden >90%. Evaluations comprised a 6-minute walk test (6MWT), 

echocardiography assessing dyssynchrony (QRS width, interventricular delay [IVD], septal-lateral delay [Ts TDI]), and NT-proBNP levels at baseline and 3-, 6-, 12-, and 18-months post-implantation. Mean follow-up was 18.2±3.1 months.

Results: Baseline characteristics matched between groups: age 72.4±10.8 vs. 73.1±11.2 years (p=0.78), LVEF 64.4±5.9% vs. 63.3±9.0% (p=0.53), NT-proBNP 248±112 vs. 262±118 pg/ml (p=0.62), 6MWT 412±98 vs. 405±102 m (p=0.71). Post-implantation, LBBAP maintained narrower QRS (109.7±8.4 vs. 138.5±11.6 ms, p<0.001), lower IVD (24.2±5.9 vs. 40.8±6.8 ms, p<0.001), and Ts TDI (44.1±14.7 vs. 102.1±9.8 ms, p<0.001). At 18 months, LVEF was superior (64.3±5.4% vs. 59.8±8.3%, p=0.042), NT-proBNP lower (195±94 vs. 392±131 pg/ml, p<0.001), and 6MWT better (492±135 vs. 338±92 m, p<0.001).

LBBAP had fewer events: HF hospitalizations 2.7% (1) vs. 10.8% (4, p=0.044); new atrial fibrillation 0% vs. 5.4% (2, p=0.045); biventricular upgrades 0% vs. 2.7% (1, p=0.31).

Conclusions: LBBAP surpasses RVA pacing in AVB patients by reducing dyssynchrony, preserving systolic function, improving functional capacity, and lowering HF/new atrial fibrillation rates via physiological activation. It is the preferred strategy for anticipated high ventricular pacing.

Protassova Elena Anatolyevna, a cardiologist, anesthesiologist, and intensive care physician at the Republican Cardiological Dispensary, a budgetary institution of the Ministry of Health of Chuvashia, also an Assistant at the Department of Surgical Diseases at I.N. Ulyanov Chuvash State University in Cheboksary. Currently, writing a scientific paper, studying the issue of electrocardiostimulation in atrioventricular block. Have a number of publications in scientific journals on this topic.