Effect of pacing site on P wave parameters: Within-patient comparison of right atrial appendage and Bachmann's bundle

Conventional right atrial appendage pacing (RAAp) is associated with adverse clinical outcomes mediated in part by electromechanical atrial delays. Bachmann's bundle pacing (BBp) offers more physiologic atrial activation; however, detailed analysis of pacing site on paced P wave parameters is lacking. Intraprocedural electrocardiograms of 21 consecutive patients undergoing atrial lead implantation were retrospectively analyzed and within-patient comparisons of 7 P wave parameters (P wave duration, P wave voltage, P wave area, PR interval, PR segment, PTFV1 and P wave axis) during sinus rhythm, RAAp and BBp performed. The median basal P wave duration was prolonged at 134.5 ms (Q1,Q3: 120.5, 150.5) and similarly prolonged during RAAp at 144.0 ms (127.0, 176.0) but was significantly reduced with BBp at 98.0 ms (93.0, 116.0; p = 0.005 and p < 0.001, respectively). The median basal P wave voltage in lead II was normal at 0.11 mV (0.08, 0.15) but significantly reduced during RAAp at 0.08 mV (0.04, 0.11) and greatest during BBp at 0.16 mV (0.09, 0.19; p < 0.001 and p = 0.003, respectively). The median basal PR interval was top normal at 185.0 ms (163.0, 213.0) and similarly prolonged during RAAp at 204.0 ms (166.5, 221.0) but was significantly shortened during BBp at 163.0 ms (142.0, 208.0; p = 0.03 and p = 0.001, respectively). BBp has favorable effects on the paced P wave parameters including marked shortening in P wave duration, increase in P wave voltage in lead II and increase in PR segment which may offer significant hemodynamic advantages over conventional RAAp.