754-2 Dual Site Atrial Pacing for the Acute and Chronic Prevention of Atrial Fibrillation: A Prospective Study

Abstract

We evaluated the feasibility of dual site atrial pacing (DAP) at the high RA & coronary sinus os &its efficacy in the immediate &chronic prevention of atrial fibrillation (AF) using a prospective crossover study design. 13 patients (pts) with drug refractory paroxysmal or chronic AF, mean age 68 ± 15 yrs, mean LV ejection fraction 49 ± 17%, mean LA diameter 37 ± 7 mm with >2 documented episodes in prior 6 mos, were considered for DAR AF was induced using 1, 2 or 3 extrastimuli at 2 to 4 RA sites & DAP was tested acutely for prevention of induced AF. Chronic DAP was instituted using 2 atrial leads & 1 ventricular lead in the DDDR mode. DAP was switched to single site atrial pacing after 3 mos while remaining in the DDDR mode. Endpoint for failure with either pacing mode was recurrent AF needing new antiarrhythmic drugs or D.C. cardioversion. 11 pts had DAP tested acutely. Mean P wave duration was 120 ± 33 ms & PA interval was 49 ± 22 ms. The effective refractory period at the coronary sinus os was 225 ± 17 ms & at the high RA was 238 ± 22 ms (p > 0.2). Acutely, DAP prevented AF in 4 of 11 pts. 8 pts had permanent pacemakers implanted to institute chronic DAR In 4 pts, DAP had been effective acutely in suppression of inducible AF whereas it was ineffective in 2 pts & was not tested in 2 pts. Atrial pacing threshold at the high RA was 0.9 ± 0.2V, at the coronary sinus os was 1.4 ± 0.2V, & with DAP was 1.5 ± 0.5V (p = 0.01 vs high RA). P wave amplitude at the coronary sinus os was 2.15 ± 0.85 mV, at the high RA was 2.75 ± 1.1 V, & with DAP was 2.52 ± IV During followup of 3 to 180 (mean 92) days, all 8 pts during DAP remained in sinus rhythm despite a decrease in antiarrhythmic drug use (mean 2.1 ± 1 before DAP vs 0.4 ± 0.5 after DAR p < 0.001). 5 pts did not require any antiarrhythmic therapy & the remaining 3 were maintained on 1 previously ineffective drug. In 1 of 4 pts switched to single site atrial pacing, sustained AF recurred requiring cardioversion. (1) DAP is feasible & can be evaluated acutely at electrophysiologic study or chronically using currently available DOOR pacemakers. (2) Acutely, DAP can suppress inducible AF in selected pts. (3) Chronically, DAP can preventAF recurrences during intermediate term followup.