Postoperative atrial fibrillation (POAF) is a common risk of left-sided heart valve surgery. However, there is limited data on the risk of thromboembolism in patients with new-onset POAF after heart valve surgery. This study aims to evaluate the long-term thromboembolic risk in patients with POAF after left-sided heart valve surgery.

In this observational cohort study, a total of 675 patients who developed POAF after isolated left-sided heart valve surgery were included. In addition, the study also included 2,025 patients with nonvalvular atrial fibrillation (NVAF). The patients with POAF were matched with patients with NVAF in a 1:3 ratio, with the primary endpoint being the rates of thromboembolism.

Out of 675 patients with POAF and 2,025 with NVAF, oral anticoagulation therapy was assigned to 420 patients with POAF (62.9%) and 1030 patients with NVAF (51.4%). The crude incidence rates of thromboembolism were higher in the POAF group (21.9%) than in the NVAF group (17.7%). However, multivariable adjustment indicated that the risk of thromboembolism was similar in patients with POAF and NVAF.

The research concluded that new-onset POAF was associated with an increased long-term risk of thromboembolism, though it was similar to the risk associated with NVAF.