Sustained electrical synchrony with left bundle branch area pacing: results at long-term follow-up

Left bundle branch area pacing (LBBAP) is an effective method to provide physiologic pacing. Several electrical parameters derived from the paced QRS complex are used to confirm LBB capture during implantation. Whether electrical synchrony persists at follow-up in patients undergoing left bundle branch area pacing (LBBAP) remains unknown.

To determine the long-term performance of electrical synchrony in a cohort of patients undergoing LBBAP by comparing electrocardiographic parameters related to LBB capture at implant and follow-up

Consecutive patients with successful LBBAP for bradycardia pacing indication and preserved left ventricular ejection fraction were selected. At follow-up, a 12-lead ECG was recorded in unipolar pacing configuration. V6-R wave peak time (RWPT), V1-RWTP and QRS duration were measured and compared to measurements at implantation.

A total of 149 patients completed the study protocol and were analyzed (mean age 77.3±9.9years, 52.3% male). Non-diseased LBB was present in 73.2% of patients. Average baseline QRS complex duration was of 116.6±28.2.

Majority of implants were performed with lumenless fixed helix leads (94%). Confirmed LBB capture was achieved in 114 patients (76.5%) and LVSP in 35 patients. Mean QRS duration (from onset) after LBBAP was 115.7±12.9 ms.

After 18.2 ± 7.3 months of follow-up visit, V6-RWPT of the LBBA captures was reduced from 77.8±11.8 ms at implant to 74.8±11.9 ms (p<0.001) (average reduction: 3.5±9.1 ms). V6-RWTP significantly decreased both among LBBP and LVSP captures (table 1). Average reduction in V6-RWPT did not differed among LBBP and LVSP captures (figure ).

V1-RWPT was reduced from 118.7±12.1 ms at implant to 112.4±11.9 ms at follow-up among the entire LBBA captures (p<0.001) (mean reduction: 6.7±10.0 ms). At follow-up V1-RWPT significantly decreased among LBBP and LVSP captures (table 1). Mean decrease in V1-RWTP tended to be higher among LBBP compared to LVSP (figure 1).

Among LBBP captures, V6-V1 interpeak interval significantly decreased, however, in LVS captures, V6-V1 interpeak interval significantly increased (table 1 and figure 1).

Paced QRS complex duration (p-QRS) significantly decreased at follow-up, among the whole study population. P-QRS, measured from pacing spike (p-QRS-stim), was reduced from 146.4±13.9 ms at implant to 138.9±13.8 ms at follow-up (p<0.001); and p-QRS, measured from onset (p-QRS-onset) decreased from 115.7±12.9 ms to 109.3±13.3 ms at follow-up (p<0.001).

Among LBBP captures, p-QRS significantly decreased, while among LVS capture patients, duration of the paced QRS complex remained stable at follow-up (table 1). Average decrease in p-QRS-stim and p-QRS-onset was higher among LBBP compared to LVS captures (figure 1).

Electrical synchrony in patients undergoing LBBAP for bradycardia pacing indications remained stable over time. LBBAP is a reliable and durable method for providing physiologic pacing.Table 1.  Figure 1