Atrial conduction delay and triggering events, such as atrial premature beats (APBs), may predispose patients to the genesis of new-onset atrial fibrillation (AF) after cardiac surgery. A prolonged P-wave duration on the signal-averaged ECG (a measure of atrial conduction delay) is a predictor of post-coronary artery bypass graft AF. Likewise, APBs are more common in the minutes and hours preceding the onset of AF in cardiac surgery patients. These observations support the concept that reducing atrial conduction time and suppressing APBs with atrial pacing may decrease the incidence of AF after cardiac surgery.
Evidence Review and Recommendations
Evidence was compiled, reviewed, and graded, and recommendations were formulated as described in the “Methodological Approach” article in this supplement. It was found that a number of randomized controlled trials have investigated the utility of atrial pacing after cardiac surgery. Each utilized either atrial pacing at a moderate rate (ie, 90 to 100 beats/min) or an atrial overdrive pacing algorithm that was designed to pace the atrium slightly faster than the underlying sinus rhythm. In all cases, pacing was performed via epicardial wires that were placed at the time of cardiac surgery. Right atrial (RA) electrodes were most often placed on the high RA near the sinus node. Left atrial (LA) electrodes were usually placed on the posterior LA between the pulmonary veins or on the roof of the LA at the Bachman bundle. Patients received RA pacing only, LA pacing only, biatrial pacing (BAP), or no atrial pacing, depending on the study design. Patients also received backup epicardial ventricular pacing electrodes. Pacing was initiated within 24 h postoperatively and generally continued for 3 to 4 days.