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

Abstract 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 the study, with 12 patients undergoing HBP implantation and another 12 patients 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). There were no significant differences 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. Clinical Perspective What is Known His Bundle Pacing (HBP) and Left Bundle Branch Area Pacing (LBBAP) have been recognized as more physiological alternatives to traditional right ventricular pacing. LBBAP has shown greater feasibility compared to HBP, although direct comparison data between the myocardial work in HBP and LBBAP are limited. What the Study Adds Our study contributes to the existing knowledge by demonstrating that both HBP and LBBAP provide physiological ventricular activation, with no significant differences observed between the two pacing modalities in terms of myocardial work and QRS duration. However, LBBAP showcased advantages such as reduced need for fluoroscopy, shorter procedural time, and improved electrical parameters. These findings further support the potential of LBBAP as a favorable pacing option. Graphical abstract