Left atrial appendage exclusion and the risk of thromboembolic events following mitral valve surgery.

Objectives: We aimed to evaluate left atrial appendage (LAA) exclusion in patients undergoing mitral valve surgery with respect to thromboembolic events.
Background: LAA is the predominant source of emboli in patients with atrial fibrillation. Prophylactic LAA exclusion at the time of heart surgery has been recommended to reduce the risk of future thromboembolism.
Methods: An observational cohort of 136 patients undergoing LAA exclusion during mitral valve surgery was identified between May 1993 and November 1998 at our institution.
Results: During a mean follow-up of 3.6 +/- 1.3 years, there were 14 (12.3%) thromboembolic events. Compared with patients who received warfarin upon hospital discharge, there were more thromboembolic events in patients not prescribed warfarin upon hospital discharge (n = 7/67, 10% vs n = 6/40, 15%, respectively). The warfarin status was not known for one patient. The majority of thromboembolic events (n = 10/14, 71%) occurred in those who underwent mitral valve repair.
Conclusion: In this observational study, patients who undergo LAA exclusion during mitral valve surgery to reduce the risk of thromboembolism have a significant incidence of thromboembolic events, especially when warfarin therapy is not prescribed upon hospital discharge.