993-43 Towards a Better Understanding of the Development of Atrial Fibrillation After Cardiac Surgery: Risk Factor Analysis in a Large Prospective Study

In a recent prospective study, we had identified prolonged p-wave duration on signal-averaged (SA) ECG as a predictor of atrial fibrillation (AF) after cardiac surgery. Although several clinical characteristics have also predicted AF, the results have been inconsistent. The purpose of the present study was to examine a variety of clinical, surgical and laboratory parameters to establish accurate risk factors, and to gain insight into the mechanism, of AF in this setting. 272 consecutive patients undergoing elective cardiac surgery were enrolled. clinical data collected and pre-op p-wave SAECG recorded. Patients were observed after cardiac surgery for the development of AF. During the period of observation, 79 of the 272 patients (29%) developed AF 2.5±1.7 days (range of 1–8 days) after surgery. 22 variables were analyzed and univariate predictors of AF were identified: EF<40%, valve surgery, pre-op use of digoxin, p-wave SAECG and p-wave on SAECG>140msec. Prior MI, HTN, pre-op use of beta blockers, aortic cross clamp time were not predictive. Multivariate analysis demonstrated that p-wave SAECG and low EF were significant independent predictors of AF. P-wave duration on SAECG > 140 msec and EF < 40% were associated with relative risks of 3.1 and 2.8, respectively. P-wave SAECG was the most sensitive test, identifying 82% of patients who experienced AF.ConclusionAF continues to be a common complication after cardiac surgery. The presence of pre-op anatomic and electrophysiologic abnormalities promote AF, and clinical variables can be used to identify those at greatest risk