Ineffectiveness and potential proarrhythmia of atrial pacing for atrial fibrillation prevention after coronary artery bypass grafting

Background. Atrial pacing is often used empirically to suppress atrial ecto py and prevent atrial fibrillation after coronary artery bypass grafting. Methods. To determine whether atrial overdrive pacing reduces atrial fibril lation and atrial ectopy after coronary artery bypass grafting, 100 patient s were randomized to no atrial pacing (Control) Versus AAI pacing at 10 bea ts/min or more above the resting heart rate (Paced), started by postoperati ve day 1 and continued through day 4. Major end points were new atrial fibr illation and frequency of atrial ectopy during the first 4 days after coron ary artery bypass grafting. Results. Atrial fibrillation occurred by day 4 in 13 of 51 (25.5%) Paced an d in 14 of 49 (28.6%) Control patients, p = 0.90. Control patients who deve loped atrial fibrillation had significantly more atrial ectopy than those w ho did not. Atrial ectopy was paradoxically more frequent in the Paced grou p (2,106 +/- 428 versus 866 +/- 385 per 24 hours, p = 0.0001). Loss of capt ure, sensing, and consistent atrial pacing occurred frequently during atria l pacing. Conclusions. Contrary to prevailing opinion and practice, postoperative atr ial overdrive pacing significantly increases atrial ectopy and does not red uce the likelihood of atrial fibrillation. (C) 2000 by The Society of Thora cic Surgeons.