Differences in Tricuspid Valve Insufficiency, Mechanical Synchrony, and Cardiac Remodeling Between Left Bundle Branch Area Pacing and Right Ventricular Pacing

BACKGROUND: Cardiac implantable electronic device-induced tricuspid regurgitation (CIED-induced TR) involves primary (lead-induced) and functional etiologies. The impact of left bundle branch area pacing (LBBAP) versus right ventricular pacing (RVP) on these mechanisms remains unclear. OBJECTIVE: To compare the incidence and mechanisms of TR among pacing modalities, and evaluate the prognostic significance of these mechanisms. METHODS: We analyzed 225 patients with first-time RV apical pacing (RVAP, n=97) or RV septal pacing (RVSP, n=78) using stylet-driven leads, and LBBAP (n=50) using lumenless leads. Echocardiography and electrocardiography were performed at baseline and 2 years post-implantation. Three-dimensional echocardiography assessed lead interference. Kaplan-Meier analysis compared event-free survival between lead-induced (LITR) and functional TR (FTR) groups. Cox regression identified predictors for adverse outcomes. RESULTS: Despite a higher baseline heart failure burden than RVP (P< .001), LBBAP showed the lowest TR progression rate (20.0% vs RVAP 43.3% vs RVSP 35.9%, P=.020) over 25.8 months. Mechanistically, LBBAP shortened QRS duration (vs RVP widening, P< .001) and demonstrated less lead interference than RVAP (28.0% vs 50.5%, P= .009). Furthermore, LBBAP showed greater left-heart reverse remodeling and improvement in mitral regurgitation, while preserving right-heart structure and function better than RVP. Over 37.4 months, LITR showed worse outcomes than FTR (P= .03). LITR, pulmonary hypertension, reduced left ventricular ejection fraction, and elevated creatinine were independent predictors for adverse outcomes. CONCLUSION: LBBAP was associated with less CIED-induced TR than RVP, likely through reduced mechanical interference, superior electrical synchrony, and favorable cardiac remodeling. Furthermore, LITR was associated with a worse prognosis than FTR.