Introduction: Postoperative atrial fibrillation commonly occurs after cardiac surgery. Occurrence of atrial fibrillation (AF) is observed in 10-50% of patients undergoing cardiac surgery. The incidence of post-operative atrial fibrillation (POAF) varies depending on patient characteristics and type of operation. It is associated not only with increased morbidity but also with prolonged hospital stay and therefore increased cost of care. The etiology of post-operative atrial fibrillation (POAF) remains incompletely understood. Several risk factors had been identified, mainly intra-operative and postoperative variables, both of which are not clinically useful in stratifying patients at risk before surgery. Among the pre-operative variables, only age and atrial dimensions, particularly left atrial volume were considered significant predictors of POAF. Echocardiography by 2d echo and by real-time 3D echo (RT3D) is useful in the noninvasive evaluation of left atrial (LA) functions. To date, we are unaware of any prospective study published that compared LA volume index to LA function for the prediction of post-operative AF.
Objective: To identify echocardiographic pre-operative predictors of post-operative atrial fibrillation among patients undergoing cardiac surgery.
Methods: Adult patients undergoing CABG surgery, and surgery involving the aortic valve, ascending aorta, tricuspid valve, pericardium and cardiac masses with preoperative 2DED and RT3D done at PHC from May to November 2009, were included in the study. The following LA parameters by 2d echo were studied: LA volume, LA volume index (LA VI), LA ejection fraction (EF), LA area, pulmonary vein peak systolic, peak diastolic and flow reversal velocities were included as well as mitral inflow velocity with peak early (E) and late velocities (A) and VTI E/A ratio. Real time 3D echo parameters included: LA stroke volume, LAVI max and LA ejection fraction. All patients were followed daily for three (3) days post-surgery with electrocardiographic telemetry for the occurrence of POAF. All telemetry data .were reviewed by an independent observer, blinded from the pre-operative assessment of LA function.
Results: Of the 60 patients included in the study, postoperative atrial fibrillation occurred in 11 (18%) patients. Clinical characteristics were similar among those who did and did not develop POAF. CABG surgery is associated with absence of atrial fibrillation. (86% versus 54%, p=0.033). Trends in the following parameters in predicting post-operative AF were noted in 2d echo such as LA VI, LA EF and LA area and in real time 3D echo these parameters included LA stoke volume and LAVI. However, these did not reach statistical significance.
Conclusion: The incidence of post-operative atrial fibrillation observed in this study is 18%. Among the echocardiographic parameters studied, there is a trend for those with higher LAVI, larger LA area and lower LA EF in the occurrence of post-operative AF.