Background: 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).
Methods and results: 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.
Conclusions: 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.