Impact of Atrial Lead Position on Functional Cardiac Parameters in Patients Requiring Dual-Chamber Pacemaker Implantation

<b>Background:</b> In patients requiring dual-chamber pacemaker (DDD) implantation, optimal atrial lead position remains a matter of debate. While most centers prefer implantation in the right atrial appendage position (Non-BB-P), due to a speculated favorable impact on atrial conduction characteristics, often, a Bachman bundle pacing (BB-P) is recommended. However, data investigating clinical outcomes in these patients are still rare. <b>Methods:</b> To evaluate this issue, in this retrospective single-center study, one-year clinical follow-up, pacemaker interrogations and available echocardiography findings in 301 consecutive patients (BB-P: age 76 ± 10 years, 46.7% female, n = 169; Non-BB-P: 77.6 ± 9 years, 50% female, n = 132, <i>p</i> = n.s.) scheduled for dual-chamber implantation were analyzed. <b>Results:</b> During follow-up, the incidence of atrial fibrillation (AF) remained similar in both groups (BB-P: 38.3%, n = 154 vs. Non-BB-P: 34.2%, n = 117 <i>p</i> = n.s.). However, we detected significantly more mode switch episodes in the BB-P group (BB-P: 51.9%, n = 154 vs. Non-BB-P: 38.8%, n = 116, <i>p</i> = 0.032). Furthermore, left ventricular functional parameters, including left ventricular ejection fraction (BB-P: 57.1 ± 8.4%, n = 60 vs. Non-BB-P: 56.0 ± 9.6, n = 45 <i>p</i> = n.s.) and incidence of diastolic dysfunction (BB-P: 55.2%, n = 67 vs. Non-BB-P: 38.3%, n = 47, <i>p</i> = n.s.), as well as the rate of left (BB-P: 58.8%, n = 68 vs. Non-BB-P: 42.0%, n = 50, <i>p</i> = n.s.) and right atrial dilatation (BB-P: 27.9%, n = 68 vs. Non-BB-P: 28.0%, n = 50 <i>p</i> = n.s.), were not significantly affected by the atrial lead position. However, stimulated p-waves were significantly shorter in BB-P vs. Non-BB-P (BB-P: 132.9 ± 23.7 ms, n = 127 vs. Non-BB-P: 139.6 ± 23.4 ms, n = 93, <i>p</i> = 0.031). <b>Conclusions:</b> In patients requiring dual-chamber implantation, the position of the atrial lead significantly altered atrial conduction, but this did not seem to affect left ventricular function parameters or the occurrence of atrial fibrillation within our follow-up period. Interestingly, we even detected more mode switch episodes in the BB-P group, hinting at an even proarrhythmic potential of BB-P. On the other hand, we found a decreased ventricular stimulation percentage in BB-P vs. Non-BB-P. Further studies should investigate the impact of Bachmann bundle pacing on clinical outcomes.