Value of the P-wave signal-averaged ECG for predicting atrial fibrillation after cardiac surgery.
BACKGROUND
Atrial fibrillation (AF) is a commonly encountered arrhythmia in clinical practice, and it occurs frequently after cardiac surgery. The P-wave signal-averaged (SA) ECG noninvasively detects atrial conduction delay. Prior studies have described greater P-wave prolongation in patients with a history of AF, but prospective studies have not been performed.


RESULTS
Consecutive patients undergoing cardiac surgery were enrolled. The P-wave SAECG was recorded before surgery from three orthogonal leads using a sinus P-wave template and a cross-correlation function. The averaged P wave was filtered with a least-squares-fit filter and combined into a vector magnitude, and total P-wave duration was measured. Patients were observed after cardiac surgery for the development of AF. One hundred thirty patients were enrolled, and 33 (25%) developed AF 2.6 +/- 2.0 days after surgery. Patients with AF more often had left ventricular hypertrophy on ECG (P < .05) and had a lower ejection fraction (P < .05). The P-wave duration on the SAECG was significantly longer in the AF patients than in those without AF: 152 +/- 18 versus 139 +/- 17 milliseconds (P < .001). An SAECG P-wave duration > 140 milliseconds predicted AF with sensitivity of 77%, specificity of 55%, positive predictive accuracy of 37%, and negative predictive accuracy of 87%. The likelihood of experiencing AF was increased 3.9-fold if the SAECG P-wave duration was prolonged. P-wave SAECG results were independent of other clinical variables by multivariate analysis.


CONCLUSIONS
The P-wave duration recorded with the SAECG is a potent, accurate, and independent predictor of AF after cardiac surgery.
Steinberg
J S
JS
Department of Medicine, St Luke's/Roosevelt Hospital Center, New York, NY 10025.
Zelenkofske
S
S
Wong
S C
SC
Gelernt
M
M
Sciacca
R
R
Menchavez
E
E
D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D006332:Cardiomegaly / Q000150:complications; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D013318:Stroke Volume