P-wave signal-averaged electrocardiogram predicts atrial fibrillation after coronary artery bypass grafting.

Abstract

AF is one of the most common complications after CABG. The aim of the study was to identify the risk factors for postoperative AF. Between June and December 2000, 129 consecutive patients (72 men, 47 women; mean age 67 +/- 6 years) underwent preoperative signal-averaged electrocardiogram (SAECG) with assessment of filtered P-wave duration (fPWD) and of the root mean square voltage of the last 10 and 20 ms of atrial depolarization (RMSV10 and RMSV20, respectively) before CABG. Fifty-six (43%) patients developed one episode of AF lasting > 30 seconds at a mean distance of 2.6 +/- 1.8 days after surgery (group A), while 73 patients remained in sinus rhythm (group B). No differences between the two groups were found in terms of age, sex, P-wave duration on the standard ECG, left atrial dimensions, and operative characteristics. In contrast, group A patients showed a significantly longer fPWD (138 +/- 10 vs 111 +/- 9 ms; P < 0.001) and smaller RMSV10 and RMSV20 (2.8 +/- 1.0 vs 4.3 +/- 1.1 microV, P < 0.001; 4.2 +/- 2.1 vs 6.2 +/- 2.0 microV, P < 0.001). Multivariate analysis indicated only fPWD as an independent predictor of AF (P = 0.009). With a cut-off value of 135 ms for fPWD, the occurrence of AF could be predicted with a sensitivity of 84%, a specificity of 73%, a negative predictive value of 85%, and a positive predictive value of 70%. Preoperative SAECG is a simple exam that correctly identifies patients at higher risk of AF after CABG. A more widespread use of this technique can be suggested.