['Increased P-wave dispersion (P-disp) and maximum P-wave duration (P-max) predict the development of atrial fibrillation (AF) in the general population. The present study evaluates the time-dependent relationship of P-disp and P-max after open heart surgery.', 'P-disp and P-max were measured in the perioperative period of open heart surgery (one day before surgery through postoperative day 4). Compared with the baseline, P-max decreased immediately after open heart surgery (112.63 +/- 7.4 ms vs 106.9 +/- 8.2 ms, P =.005). An increase in P-disp was observed between postoperative days 1 and 2 (37.5 +/- 6.8 ms vs 43.1 +/- 4.5 ms, P <.05), and postoperative days 1 and 3 (37.5 +/- 6.8 ms vs 44.1 +/- 6.6 ms, P <.05). There was also an increase in the P-max between postoperative day 1 and 3 (103 +/- 8.3 ms vs 110 +/- 7.7 ms, P <.05).'] Are changes in P-wave dispersion and P-wave duration after open heart surgery associated with the peak incidence of atrial fibrillation?