Ultra-high-frequency electrocardiography identifies preserved ventricular synchrony during left bundle branch area...

Right ventricular pacing (RVP) may induce nonphysiological ventricular activation and electrical dyssynchrony, whereas left bundle branch area pacing (LBBAP) is intended to recruit the His-Purkinje system and preserve a more physiological activation pattern.

To compare paced-state ventricular activation profiles during LBBAP and RVP using ultra-high-frequency electrocardiography (UHF-ECG).

In this single-center pilot comparative study, 33 patients undergoing permanent pacing were analyzed (16 LBBAP, 17 RVP). The UHF-ECG comparison was performed exclusively during paced rhythm. Baseline clinical characteristics and paced-state QRS duration, absolute ventricular electrical delay (|VED16|), and mean ventricular delay (MeanVD) were compared between groups. Continuous variables were analyzed with the two-sided Mann-Whitney U test, categorical variables with Fisher's exact test, and effect sizes with Cliff's delta.

Age, sex, left ventricular ejection fraction, and NYHA class were broadly comparable between groups, but pacing indication differed. During pacing, LBBAP showed a narrower QRS complex than RVP (108.1 ± 12.9 vs 137.3 ± 18.2 ms; p < 0.0001), lower |VED16| (16.3 ± 12.7 vs 30.0 ± 14.9 ms; p = 0.015), and lower MeanVD (41.8 ± 10.2 vs 54.1 ± 10.9 ms; p = 0.0033). Paced QRS duration ≥120 ms occurred in 6.3% versus 82.4% (p < 0.0001).

Compared with RVP, LBBAP was associated with a more physiological paced ventricular activation pattern characterized by a narrower QRS complex and lower UHF-ECG dyssynchrony metrics.