Signal-averaged P-wave duration does not predict atrial fibrillation afterthoracic surgery

Background: Atrial fibrillation (AF) is the most common dysrhythmia seen ea rly after major thoracic surgery but occurs infrequently after minor thorac ic or other operations. A prolonged signal-averaged P-wave duration (SAPWD) has been shown to be an independent predictor of AF after cardiac surgery. The authors sought to determine whether a prolonged SAPWD alone or in comb ination with clinical or echocardiographic correlates predicts AF after ele ctive noncardiac thoracic surgery. Methods: Of the 250 patients enrolled 228 were included in the final analys is. Preoperative SAPWD was obtained in 155 patients who had major thoracic surgery and in 73 patients undergoing minor thoracic or other operations wh o served as comparison control subjects. The SAPWD was recorded from three orthogonal leads using a sinus P-wave template. The filtered vector composi te was used to measure total P-wave duration. Clinical, surgical, and echoc ardiographic parameters were collected and patients followed for 30 days af ter surgery for the development of symptomatic AF. Results: Symptomatic AF developed in 18 of 155 (12%) patients undergoing ma jor thoracic surgery and in 1 of 73 (1%) patients having minor thoracic or abdominal surgery, most commonly 2 or 3 days after surgery. In comparison w ith similar patients undergoing major thoracic surgery without AF, those wh o developed AF were older(66 +/- 8 vs. 62 +/- 10 yr; P = 0.04) but did not differ in SAPWD (145 +/- 17 vs. 147 +/- 16, ms) in standard electrocardiogr aphic P-wave duration (105 +/- 7 vs. 107 +/- 10 ms), incidence of left-vent ricular hypertrophy on 12-lead electrocardiographic, male sex, history of h ypertension, diabetes, or coronary heart disease. Thoracic-surgery patients at risk for postoperative AF did not differ from all other patients at low risk for AF in clinical or SAPWD parameters. Conclusions: Under the conditions of this study, SAPWD did not differentiat e patients who did or did not develop AF after noncardiac thoracic surgery, and therefore its measurement cannot be recommended for the routine evalua tion of these patients. Older age continues to be a risk factor for AF afte r thoracic surgery.