A randomized comparison of permanent septal versus apical right ventricular pacing: short-term results.

Objectives: This study compared chronic right ventricular (RV) pacing at the septum versus apex.

Background: Chronic RV apical pacing may be detrimental to ventricular function. This randomized, pilot study examined whether, compared with apical, permanent septal pacing preserves cardiac function.

Methods: Ablation of the atrioventricular junction for permanent AF, followed by implantation of a DDDR pacemaker connected to two ventricular leads was performed in 28 patients. One lead screwed into the septum and another placed at the apex were connected to the atrial and ventricular port, respectively. Septum or apex was paced by programming AAIR or VVIR modes, respectively. Patients were randomly assigned, 4 months later, to pacing at one site for 3 months, and crossed over to the other for 3 months. New York Heart Association class, QRS width and axis, left ventricular ejection fraction (LVEF), exercise duration, and peak oxygen uptake were measured. Results in patients with LVEF > 45% and < or = 45% were compared.

Results: Septal pacing was associated with shorter QRS (145 +/- 4 msec vs 170 +/- 4 msec, P < 0.01) and normal axis (40 degrees +/- 10 degrees vs -71 +/- 4 degrees , P < 0.01). At 3 months, among patients with baseline LVEF < or = 45%, LVEF was 42 +/- 5% after septal pacing versus 37 +/- 4% after apical pacing (P < 0.001).

Conclusion: In contrast to RV apical pacing, chronic RV septal pacing preserved LVEF in patients with baseline LVEF < or = 45%.