Comparison of electrocardiographic parameters between left bundle optimized cardiac resynchronization therapy (LOT‐CRT) and left bundle branch pacing—cardiac resynchronization therapy (LBBP‐CRT)

Background In patients undergoing cardiac resynchronization therapy using left bundle branch area pacing (LBBP‐CRT), the addition of a coronary sinus lead, that is, Left bundle optimized CRT (LOT‐CRT) might confer additional benefits. Objectives To compare the electrocardiographic characteristics between LBBP‐CRT and LOT‐CRT Materials and Methods Patients with non‐ischemic cardiomyopathy (NICMP) and left bundle branch block (LBBB) with left ventricular ejection fraction <35% who underwent implantation of an atrial lead, a left bundle lead, and a coronary sinus lead were included in this prospective study. Digital 12‐lead electrocardiograms were recorded in three pacing modes—AAI, DDD with pacing from the LBB lead (LBBP‐CRT), and DDD with pacing from both left bundle and coronary sinus leads (LOT‐CRT). QRS duration (QRSd), QRS area, QT interval, and T peak–T end (TpTe) intervals were compared. Results Among 24 patients, QRSd reduced from 167 ± 21.2 ms to 134.5 ± 23.6 ms with LBBP‐CRT ( p < .001) and 129.5 ± 18.6 ms with LOT‐CRT ( p < .001) without a significant difference between LBBP‐CRT and LOT‐CRT ( p = .15). Patients with QRS duration with LBBP‐CRT > 131 ms showed a significant reduction in QRSd with LOT‐CRT ( p = .03). QT interval was reduced with both modes of CRT. LOT‐CRT was associated with a greater reduction in QRS area ( p = .001), TpTe interval ( p = .03), and TpTe/QT ratio ( p = .013) compared to LBBP‐CRT. Conclusions In patients with NICMP and LBBB, there was no significant difference in QRSd with LOT‐CRT compared to LBBP‐CRT. However, in patients with QRSd > 131 ms after LBBP‐CRT, LOT‐CRT resulted in a significantly narrower QRS.