Randomized crossover comparison of right atrial appendage pacing versus interatrial septum pacing for prevention of paroxysmal atrial fibrillation inpatients with sinus bradycardia

Background New atrial pacing techniques and overdrive pacing algorithms hav e been introduced to prevent atrial fibrillation. This study was designed t o test the hypotheses that (I) interatrial septum pacing (IASP) at the tria ngle of Koch would be more effective than right atrial appendage pacing (RA AP) in preventing paroxysmal atrial fibrillation (PAF) in patients with sin us bradycardia and (2) an algorithm (CAP) designed to achieve constant atri al capture would increase the efficacy of rate-responsive atrial pacing. Methods We studied 46 patients with PAF and sinus bradycardia implanted wit h a DDD(R) (Medtronic Thera) pacemaker. Twenty-four patients (6.0 +/- 10.1 PAF episodes/month within 3 months before study) were randomized to RAAP an d 22 patients (5.4 +/- 7.1, not significant) to IASP. Within each arm 2 ran domized crossover periods of CAP-OFF and CAP-ON function were programed. Results The PAF episodes per month significantly decreased in the RAAP (CAP -OFF: 2.1 +/- 4.2, P < .05; CAP-ON: 1.9 <plus/minus> 3.81 P < .05) and in t he IASP group (CAP-OFF: 0.2 <plus/minus> 0.5, P < .05; CAP-ON: 0.2 0.5, P < .05). Values were significantly lower in the IASP group than in the RAAP g roup in both CAP-OFF (0.2 0.5 vs 2.1 4.2, P < .05) and CAP-ON (0.2 0.5 vs 1 .9 <plus/minus> 3.8, P < .05) conditions. PAF burden was significantly lowe r in the IASP than in the RAAP group in CAP-OFF (47 <plus/minus> 84 min/d v s 140 +/- 217, P < .05) and in CAP-ON (41 <plus/minus> 72 vs 193 +/- 266, P < .05) conditions. No differences were observed within each arm in PAF bur den between the 2 crossover CAP programing periods. Conclusions Rate-adaptive IASP at the triangle of Koch is more effective th an RAAP in preventing PAF in patients with sinus bradycardia. In our sample of patients no additional clinical benefit is furnished by the CAP algorit hm.