Prediction of Atrial Fibrillation via Atrial Electromechanical Interval After Coronary Artery Bypass Grafting

Abstract

We assessed the validity of the atrial electromechanical interval, measured by transthoracic tissue Doppler echocardiography, in determining patients at risk of post-coronary artery bypass graft atrial fibrillation (AF). This prospective study recruited 355 patients in sinus rhythm who were candidates for coronary artery bypass grafting. The patients underwent a preoperative transthoracic echocardiography with a tissue Doppler evaluation and were monitored with continuous ECG telemetry during their hospital stay. Sixty-eight patients had postoperative AF (19.2%), with the incident occurring 2.3+/-0.7 days after surgery. The median length of hospitalization was 7.0 days for the AF patients and 6.0 days for the non-AF patients (P<0.0001). The subjects with postoperative AF differed from the sinus rhythm patients in that the former had a lower ejection fraction (40.4+/-8.5% versus 48.4+/-9.4%), a reduced maximal A-wave transmitral Doppler flow velocity (44.3+/-4.6 versus 53.3+/-10.9 cm/s), an increased total atrial volume (68.7+/-12.6 versus 55.3+/-11.8 mL), and a prolonged atrial electromechanical interval (141.9+/-13.4 versus 100.3+/-10.3 ms, respectively; P<0.0001 for all). In addition, the AF patients were older than the sinus rhythm group (66.0+/-8.0 versus 59.8+/-8.5 years). The atrial electromechanical interval was the best independent discriminator of the history of AF. We defined a cutoff point for the atrial electromechanical interval and chose 120 milliseconds for categorization, which yielded 100% sensitivity and 94.8% specificity for the prediction of AF. The atrial electromechanical interval by transthoracic tissue Doppler echocardiography could be a valuable method for identifying patients vulnerable to post-coronary artery bypass graft AF.