Selection of pacing mode after interruption of atrioventricular conduction for atrial fibrillation: observations from the PA3 clinical trial.

The optimal pacing mode for patients with paroxysmal atrial fibrillation (AF) following AV junction ablation remains the subject of some debate. Recent clinical trials have not demonstrated a superior advantage of maintenance of sinus rhythm over the rate control approach. However, clinical trials in pacemaker populations have demonstrated that physiologic pacing reduces the probability of paroxysmal and persistent AF compared to ventricular pacing. In the second phase of the PA(3) study, patients were randomized to DDDR versus VDD pacing in a cross over study design. Of the 67 patients randomized, 42% developed permanent AF within one year following ablation. AF frequency and burden increases early following AV junction ablation suggesting that ventricular pacing even in an atrial synchronous mode promotes AF. Given the high probability of permanent AF developing early following ablation, VVIR pacing appears to be the appropriate pacing mode for symptomatic patients undergoing total AV junction ablation.