Atrial fibrillation after coronary artery bypass surgery: P wave signal averaged ECG, clinical and angiographic variables in risk assessment.
BACKGROUND
Atrial fibrillation (AF) is a commonly encountered arrhythmia and occurs in up to 40% of patients after coronary artery bypass surgery (CABG). The preoperative signal averaged ECG (SAECG) P wave may be useful indicator of AF after CABG. We prospectively analyzed the predictive value of SAECG P wave compared to clinical variables.


METHODS
Fifty-three patients with coronary artery disease undergoing first elective CABG were enrolled. All patients had P wave specific SAECG, standard 12 lead ECG, ejection fraction and left atrial posteroanterior diameter from the echocardiogram within the 24 h before surgery. From the SAECG P wave, filtered P wave duration was measured. Lead II P wave duration, left atrial enlargement and left ventricular hypertrophy were determined from standard ECG. Patients were continuously monitored during their postoperative period and serial ECGs were taken.


RESULTS
During an observation period of up to 16 days, 19 (35.8%) patients developed AF 2.8+/-1.3 days after CABG. Patients with AF more often had left atrial enlargement (LAE) on ECG (P = 0.041) and right coronary artery (RCA) lesion (P = 0.0034). The filtered P wave duration on the SAECG was significantly longer in the AF patients than those without AF (129.7+/-13.2 ms versus 113.9+/-9.0 ms, P = 0.001). Logistic regression analysis identified independent predictors, estimated adjusted relative risk (95% confidence interval) of AF: with LAE, the relative risk was 2.72 (1.13-5.82), RCA lesion, the relative risk was 3.06 (1.45-6.45) and SAECG P wave duration >122.3 ms, the relative risk was 4.58 (2.11-9.97). The occurrence of AF was predicted by electrocardiographically determined left atrial enlargement with a sensitivity of 36%, specificity of 88%, positive predictive accuracy of 63%, negative predictive accuracy of 71%. If presence of right coronary artery lesion was evaluated these values were 63%, 79%, 63%, 79% subsequently. P wave duration >122.3 ms had a sensitivity of 68%, specificity of 88%, positive predictive accuracy of 76%, negative predictive accuracy of 83%. If both P wave >122.3 ms and presence of right coronary artery lesion were combined, these values were 47%, 94%, 81%, 76% subsequently.


CONCLUSIONS
The predictors of AF after CABG were left atrial enlargement on standard 12 lead ECG, RCA lesion and SAECG P wave duration. Among these predictors, SAECG P wave duration was the best predictor of AF after CABG.
Aytemir
K
K
Hacettepe University, Faculty of Medicine, Department of Cardiology, Ankara, Turkey. kaytemir@hotmail.com
Aksoyek
S
S
Ozer
N
N
Aslamaci
S
S
Oto
A
A
D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology*; D017023:Coronary Angiography / Q000379:methods; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004452:Echocardiography; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods