Left bundle branch pacing on mechanical synchrony and myocardial work in bradycardia patients

A Comparative Assessment of Myocardial Work Performance during Spontaneous Rhythm, His Bundle Pacing, and Left Bundle Branch Area Pacing: Insights from the EMPATHY Study

BACKGROUND

Physiological pacing has gained significant interest due to its potential to achieve optimal hemodynamic response. This study aimed to assess left ventricular performance in terms of electrical parameters, specifically QRS duration and mechanical performance, evaluated as myocardial work. We compared His Bundle Pacing (HBP) and Left Bundle Branch Area Pacing (LBBAP) to evaluate their effects.

METHODS

Twenty-four patients with class I or IIa indications for pacing were enrolled in this study, with twelve patients undergoing HBP implantation and another twelve undergoing LBBAP implantation. A comprehensive analysis of myocardial work was conducted.

RESULTS

Our findings indicate that there were no major differences in terms of spontaneous and HBP activation in myocardial work, except for global wasted work (217 mmHg% vs. 283 mmHg%; p 0.016) and global work efficiency (87 mmHg% vs. 82 mmHg%; p 0.049). No significant differences were observed in myocardial work between spontaneous activation and LBBAP. Similarly, no significant differences in myocardial work were found between HBP and LBBAP.

CONCLUSIONS

Both pacing modalities provide physiological ventricular activation without significant differences when compared to each other. Moreover, there were no significant differences in QRS duration between HBP and LBBAP. However, LBBAP demonstrated advantages in terms of feasibility, as it achieved better lead electrical parameters compared to HBP (threshold@0.4 ms 0.6 V vs. 1 V; p = 0.045-sensing 9.4 mV vs. 2.4 mV; p < 0.001). Additionally, LBBAP required less fluoroscopy time (6 min vs. 13 min; p = 0.010) and procedural time (81 min vs. 125 min; p = 0.004) compared to HBP.

Left bundle branch pacing preserved left ventricular myocardial work in patients with bradycardia

Background

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. Left ventricular (LV) myocardial work (MW) incorporates afterload and LV global longitudinal strain to estimate global and segmental myocardial contractility. However, the effect of LBBP on LV MW remains unknown. This study aimed to evaluate the impact of LBBP on LV MW in patients receiving pacemaker for bradyarrhythmia.

Methods

We prospectively enrolled 70 bradycardia patients with normal LV systolic function receiving LBBP (n = 46) and non-selective His-bundle pacing (NS-HBP) (n = 24). For comparative analysis, patients receiving right ventricular pacing (RVP) (n = 16) and control subjects (n = 10) were enrolled. Two-dimensional speckle tracking echocardiography was performed. The LV pressure-strain loop was non-invasively constructed to assess global LV MW.

Results

After 6-month follow-up, LBBP group (with >40% ventricular pacing during 6 months) had shorter peak strain dispersion (PSD) compared with RVP group, and higher LV global longitudinal strain compared with RVP group and NS-HBP group, but had no difference in left intraventricular mechanical dyssynchrony, including septal-to-posterior wall motion delay and PSD, compared with NS-HBP group. During ventricular pacing, LBBP group had higher global MW index (GWI) (2,189 ± 527 vs. 1,493 ± 799 mmHg%, P = 0.002), higher global constructive work (GCW) (2,921 ± 771 vs. 2,203 ± 866 mmHg%, P = 0.009), lower global wasted work (GWW) (211 ± 161 vs. 484 ± 281 mmHg%, P < 0.001) and higher global MW efficiency (GWE) (91.4 ± 5.0 vs. 80.9 ± 8.3%, P < 0.001) compared with RVP group, and had lower GWW (211 ± 161 vs. 406 ± 234 mmHg%, P < 0.001) and higher GWE (91.4 ± 5.0 vs. 86.4 ± 8.1%, P < 0.001) compared with NS-HBP group.

Conclusions

In this study we found that in patients with mid-term (6-month) high ventricular pacing burden (>40%), LBBP preserved more LV MW compared with NS-HBP and RVP. Further studies are warranted to assess the association between LV MW and long-term clinical outcomes in LBBP with high ventricular pacing burden.