Cardiac resynchronization therapy with left bundle branch area pacing reverts electromechanical window negativity to a similar extent as biventricular pacing

Background Cardiac resynchronization therapy (CRT) through left bundle branch area pacing (LBBAP) has been associated with reduced arrhythmogenic risk compared to biventricular pacing (BiVP). Electromechanical window (EMW) is a marker of electromechanical instability, and a negative EMW is associated with ventricular arrhythmias. We hypothesized that LBBA-CRT increases EMW at least as much as BiVP-CRT does. Methods 129 CRT-recipients (LBBAP: n=63; BiVP: n=66) were included. EMW and echocardiographic reverse remodeling were evaluated before and 6–12 months after CRT implantation in the entire cohort and in a subgroup of patients with a negative EMW at baseline. EMW is calculated by subtracting the QT interval from the time interval of QRS onset to the aortic valve closure artifact (QAoC) using CW-Doppler echocardiography. Results EMW measurements were feasible in 67% of patients (n=86). No significant difference in ΔEMW was observed between LBBAP and BiVP. In patients with a negative EMW at baseline, both CRT strategies led to significant EMW increase (LBBAP: n=21, ΔEMW +13 ms (IQR -1 to 70), p=0.003; BiVP: n=36, ΔEMW +26 ms (IQR -2 to 54), p=0.006), there was no significant difference between CRT-groups (p=0.779). Left ventricular ejection fraction improved by 10%±11% and end-diastolic volume decreased by 37±51 ml (< 0.001), with no significant differences between LBBAP and BiVP. In multivariate analysis, a negative EMW at baseline, but not echocardiographic reverse remodeling, was the only independent predictor of EMW increase. Conclusion In CRT patients with a negative EMW at baseline, LBBAP and BiVP revert EMW to a similar degree.