Re-evaluation of the role of P-wave duration and morphology as predictors of atrial fibrillation and flutter after coronary artery bypass surgery.

To evaluate the significance of P-wave duration and morphology for the development of post-operative atrial fibrillation/flutter, we investigated 189 consecutive patients scheduled for elective coronary artery bypass surgery. The longest pre-operative total P-wave duration was measured from the standard electrocardiogram at a paper speed of 50 mm.s-1 (mean of two independent observers). By the signal averaging technique we determined the pre-operative total P-wave duration, and root-mean square voltage of the last 10, 20, and 30 ms of the filtered (40-250 Hz) P-wave from a vector composite of three orthogonal leads at noise level 0.2 microV. Forty-two (22%) of the patients developed atrial fibrillation/flutter. Older age (mean +/- SD) 62 +/- 8 vs 56 +/- 8 years (P < 0.000), increasing body weight 83 +/- 11 vs 79 +/- 12 kg (P = 0.05), treatment for hypertension 26 vs 13% (P = 0.04), and a longer P-wave duration in the standard electrocardiogram 129 +/- 12 vs 124 +/- 12 ms (P = 0.01) were associated with development of atrial fibrillation/flutter documented by a 12-lead electrocardiogram. Logistic regression analysis identified independent predictors, estimated adjusted relative risk (95% confidence interval) of atrial fibrillation/flutter: with age > 60 years, the relative risk was 4.46 (2.05-9.73), and body weight > 80 kg, the relative risk was 3.81 (1.71-8.46). Thus, P-wave duration and morphology did not provide significant information on the risk of atrial fibrillation/flutter when controlling for the effects of increasing age and body weight.