Atrial overdrive pacing has been commonly practiced after cardiac surgery in hopes of suppressing atrial ectopy and postoperative atrial fibrillation. However, several studies show inefficacy with AAI pacing and some suggest a potential for proarrhythmia. In a study of AAI right atrial pacing after cardiac surgery, atrial ectopy was increased with no effect on atrial fibrillation suppression. Undersensing and loss of capture were observed not infrequently. Best efficacy for prevention of postoperative atrial fibrillation from other studies suggest that biatrial or Bachmann's bundle pacing, triggered mode pacing, atrial overdrive algorithms, or concomitant beta-blocker use might be more effective than single site right atrial pacing in the AAI mode. However, even with biatrial pacing, proarrhythmia has been reported, and this potential risk for increased atrial ectopy or atrial fibrillation should be recognized. Proarrhythmia may be precipitated by inappropriate sensing or loss of pacing associated with pacing through temporary wires.