Increases in P-wave dispersion predict postoperative atrial fibrillation after coronary artery bypass graft surgery.

Atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. In this study we examined the effect of surgery on atrial electrophysiology as measured by P-wave characteristics and to determine the potential predictive value of P-wave characteristics on the incidences of postoperative AF in patients undergoing CABG surgery. Patients undergoing elective CABG surgery were monitored by continuous electrocardiogram (ECG) telemetry during the in-hospital period until discharge for the occurrence of postoperative AF. Differences in P-wave characteristics (P-wave duration, amplitude, axis, dispersion, PR interval, segment depression, and dispersion) were compared between the pre- and postoperative 12-lead ECG measurements, and also between patients with and without postoperative AF. The association of postoperative AF and potential clinical predictors and P-wave characteristics were determined by multivariate logistic regression. Postoperative AF occurred in 81 (27%) of 300 patients. Univariate analysis showed that patients who subsequently developed postoperative AF compared with those without AF were significantly older (mean age 68 ± 8 versus 63 ± 10 yr, P < 0.0001), had a larger body surface area (BSA) (2.03 ± 0.24 versus 1.92 ± 0.22 m 2 , P = 0.0002), were more likely to have a history of AF (8 of 81 versus 1 of 219, P = 0.003), used preoperative antiarrhythmic medications more frequently (7 of 81 versus 4 of 219, P = 0.01), and had a more frequent rate of return to the operating room for postoperative complications (9 of 81 versus 9 of 219, P = 0.029). Furthermore, the postoperative P-wave duration decreased to a larger extent (mean change -11.3 ± 0.1 ms versus -8.4 ± 0.1 ms, P < 0.0001), and the P-wave dispersion increased postoperatively to a larger extent (3.1 ± 15.5 ms versus -1.6 ± 14.6 ms, P = 0.028) in those who subsequently developed AF compared with those without AF. Multivariate logistic regression showed age (odds ratio [OR] = 1.1, 95% confidence interval [Cl]: 1.06-1.15, P < 0.0001), BSA (OR = 38.1, 95% CI: 8.2-176, P < 0.0001), and an increase in postoperative P-wave dispersion (OR = 1.03, 95% CI: 1.01-1.05, P = 0.01) to be independent predictors of postoperative AF. No surgical factor was identified to be responsible for this postoperative change in atrial electrophysiology.