Left Atrial Appendage Emptying Velocity Does Not Predict Postoperative Atrial Fibrillation in Patients Undergoing Cardiopulmonary Bypass

BACKGROUND: Atrial fibrillation is a common complication of cardio-pulmonary bypass and improved pre-operative risk assessment could help guide prophylactic therapy. This study examined whether reduced left atrial appendage flow velocities measured by transoesophageal echocardiography pre-operatively in patients in sinus rhythm predicted development of postoperative atrial fibrillation. METHODS AND RESULTS: All patients who underwent transoesophageal echocardiography for clinical indications with measurements of left atrial appendage velocities within twelve months prior to cardio-pulmonary bypass were retrospectively identified. Postoperative records were reviewed and the patients divided into two groups based on the presence or absence of clinically significant atrial fibrillation during hospitalization following cardio-pulmonary bypass. Thirty-six patients (mean age 61.1 +/- 14.8 years, 18M/18F) were included in the study. The overall incidence of atrial fibrillation in the cohort was 17/36 patients (47%). Mean left atrial appendage emptying velocity was 50.8 +/- 23.3 cm/s2 (range 26-119) in the patients with sinus rhythm only and 41.5 +/- 16.7 cm/s2 (range 16-76), in the patients with postoperative atrial fibrillation (P=ns). CONCLUSIONS: In our patient population there was no significant difference in left atrial appendage emptying velocity measured by transoesophageal echocardiography in patients with and without postoperative atrial fibrillation. Pre-operative measurement of left atrial appendage emptying velocity cannot be relied upon to risk stratify patients prior to cardio-pulmonary bypass.