Does atrial overdrive pacing prevent paroxysmal atrial fibrillation in paced patients?

The role of atrial overdrive pacing for the suppression of paroxysmal atria l fibrillation remains unclear. To investigate this we have performed a ran domised study evaluating the role of an increased atrial base rate in suppr essing this arrhythmia in patients implanted with a permanent pacemaker (Ch orum ELA) for sick sinus syndrome with previous documented paroxysmal atria l fibrillation. Twenty-seven patients (mean age, 69; 15 female) were random ised to two 3-month single-blinded crossover periods of DDDR pacing. The pa cemaker was set with a base rate of 60 bpm (normal) during one period and a t 10 bpm (overdrive) above the average heart rate during the other, mean (S .D.) 75+/-7 beats/min (range, 70-96). The fallback algorithm of the pacemak er was activated to record the number and duration of paroxysmal atrial fib rillation episodes. During the overdrive period there was a significant inc rease in the total duration of atrial pacing (normal 60+/-26% vs. overdrive 72+/-28%, P<0.001). However there was no significant difference in the num ber of paroxysmal atrial fibrillation episodes (normal 43+/-109 vs. overdri ve 43+/-106, P=ns), or their total duration (normal 42+/-108 h vs. overdriv e 99+/-254 h, P=ns). In conclusion, atrial overdrive pacing, achieved by in creasing the atrial base rate, has no incremental benefit in the suppressio n of paroxysmal atrial fibrillation when compared to rate responsive pacing with a base rate of 60 bpm. (C) 2000 Elsevier Science Ireland Ltd. All rig hts reserved.