This study sought to evaluate the effectiveness of His-optimized cardiac resynchronization therapy (HOT-CRT) for reducing left ventricular activation time (LVAT) compared to His bundle pacing (HBP) and biventricular(BiV) pacing (including multipoint pacing [MPP]), using electrocardiographic (ECG) imaging.

HBP may correct bundle branch block (BBB) and has shown encouraging results for providing CRT. However, HBP does not correct BBB in all patients and may be combined with univentricular or BiV fusion pacing to deliver HOT-CRT to maximize resynchronization.

Nineteen patients with a standard indication for CRT, implanted with HBP without correction of BBB and BiV (n=14) or right ventricular (n=5) leads, were prospectively enrolled. Patients underwent ECG imaging while pacing in different configurations using different LV electrodes and at different HBP ventricular pacing (VP) delays. The primary endpoint was reduction in LVAT with HOT-CRT, and the secondary endpoints included various other dys-synchrony measurements including right ventricular activation time (RVAT).

Compared to HBP, HOT-CRT reduced LVAT by 21% (−17 ms [95% confidence interval [CI]: −25 to −9 ms]; p < 0.001) and outperformed BiV by 24% (−22 ms [95% CI: −33 to −10 ms]; p = 0.002) and MPP by 13% (−11 ms [95% CI: −21 to −1 ms]; p = 0.035). Relative to HBP, HOT-CRT also reduced RVAT by 7% (−5 ms [95% CI: −9 to −1 ms; p = 0.035) in patients with right BBB, whereas RVAT was increased by BiV. The other electrical dyssynchrony measurements also improved with HOT-CRT.

HOT-CRT acutely improves ventricular electrical synchrony beyond BiV and MPP. The impact of this finding needs to be evaluated further in studies with clinical follow-up. (Electrical Resynchronization and Acute Hemodynamic Effects of Direct His Bundle Pacing Compared to Biventricular Pacing; NCT03452462).