Acute P wave and procedural characteristics during Bachmann bundle pacing in patients with interatrial conduction delay

Introduction Interatrial conduction delay has been associated with de novo occurrence of atrial fibrillation, as well as recurrence after electrical cardioversion or ablation. Initial data have shown that correction of interatrial block with Bachmann bundle pacing (BBP) results in a significant reduction in atrial fibrillation episodes. This may be due to better biatrial electrical activation and mechanics. Purpose This feasibility study evaluated the P wave characteristics before and after BBP, as well as the pacing parameters in patients with baseline interatrial partial or complete block. Methods Between March and September 2025, 15 patients who underwent successful BBP for baseline interatrial conduction delay were included in the analyses. The procedures were performed using 3D-shaped delivery catheters and lumenless or conventional stylet-driven leads and were fluoroscopically and electrogram guided. Procedural success was defined according to the commonly used atrial electrogram and P wave electrocardiographic criteria. P wave duration, amplitude, area, and dispersion were measured. Procedural parameters were also recorded. Results The mean age of the patients was 71.6 ± 7.7 years, and 66.7% of the patients were male. Ten BBP procedures were performed using lumenless leads, while stylet-driven leads were used in five patients. BBP significantly reduced the P wave duration in lead DII from 142.5 ± 19.5 ms to 113.5 ± 12.7 ms (p<0.001). The P-wave amplitude measured in lead DII increased from a baseline value of 0.12 ± 0.04 mV to 0.16 ± 0.06 mV after BBP (p=0.007). Also, there was a significant change in P wave dispersion from 20.7 ± 7.5 ms to 9.7 ± 3.8 ms (p<0.001). On the other hand, there was no change in P wave area (9.05 ± 3.7 mm x mV vs. 9.16 ± 3.5 mm x mV, p=0.9). The acute pacing threshold was 1.05 ± 0.5 V at 0.4 ms pulse duration, and the sensing threshold was 1.9 ± 0.8 mV. The recorded impedance was 622 ± 222 Ohms. There were no significant differences in thresholds between lumenless and stylet-driven leads. Conclusions BBP is a feasible technique, achieved with both lumenless and stylet-driven leads, that significantly improves the P wave characteristics in patients with baseline interatrial conduction delay.