Oral anticoagulation following bioprosthetic SAVR in patients with atrial fibrillation: what’s the current status of NOACs?

The burden of non-rheumatic valvular heart disease has increased rapidly due to the worldwide ageing population [1]. More than 24 million people suffer from degenerative mitral valve disease, while calcific aortic disease steadily rises, reaching 9 million cases before the pandemic [1, 2]. Repair or replacement of the diseased valve by either mechanical or biological prosthesis remains the only definitive treatment for patients with valvular heart disease. Over 200 000 heart valve replacement surgeries are performed annually worldwide, with a predicted increment to 850 000 per year by 2050 [3]. Over the last 2 decades, a massive shift from mechanical to bioprosthetic heart valve (BHV) replacements has been noticed [4], despite unresolved durability issues. The change to a BHV strategy could be partially explained by the preference of younger individuals to avoid lifelong treatment with a vitamin K antagonist (VKA), which mechanical heart valves warrant, and more elderly patients at higher bleeding risk being treated. Surgical replacement of a diseased valve aims to improve symptoms and prolong life but exposes the patient to potential prosthesis-related complications. Although less thrombogenic than mechanical heart valves, tissue valves are also prone to cause thromboembolic complications, and the risk is exceptionally high during the first 3 months after the operation [5]. Despite the frequency of BHV usage, the optimal postoperative anticoagulation strategy remains unclear. This is especially true for decision-making in cardiac surgery patients with incremental risk of thromboembolic complications, such as prolonged immobility, stroke, malignancy, prior and de novo atrial fibrillation (AF), congestive heart failure, history of major venous and pulmonary thromboembolism and hypercoagulable conditions. Focused research on these clinical scenarios was considered less important, and the academic community has concentrated chiefly on assessing structural failure. Consequently, postsurgical antithrombotic management is based not on valuable research findings but rather on local habits. Recently, however, surgical and transcatheter BHV thrombosis and the prevention of thromboembolic complications have attracted significant attention due to better imaging surveillance [3]. The lack of robust data on the efficacy and safety of different anticoagulation regimens is reflected by seeing lower levels of evidence (LOEs) behind the recommendations in the recently released European Society of Cardiology (ESC)/European Association for Cardio-Thoracic Surgery (EACTS) Guidelines for the management of valvular heart disease [6]. For patients with no baseline indication for oral anticoagulation (OAC), the ESC/ EACTS guidelines recommend either low-dose aspirin (75– 100 mg/day) or a VKA for the first 3 months after surgical implantation of an aortic BHV [class of recommendation (COR) IIa, LOE B]. For those who received a BVH in the mitral or tricuspid position, a VKA should be considered as the anticoagulation strategy (COR IIa, LOE B). For patients undergoing surgical implantation of a BHV with other anticoagulation indications, the guidelines recommend treatment with OAC (COR I, LOE C). However, the choice between a VKA and a non-vitamin K antagonist (NOAC) remains uncertain. The guidelines recommend that an NOAC be considered over a VKA 3 months after surgical implantation of a BHV in the aortic position in patients with AF (COR IIa, LOE B). In addition, an NOAC over a VKA may be considered after 3 months following surgical implantation of a BHV in the mitral position in patients with AF, but this is a weak recommendation based on low-quality evidence (COR IIb, LOE C). In this issue of the journal, Magro and Sousa-Uva [7] report the results of a systematic literature search and critical appraisal of available evidence to answer an essential clinical question of whether the efficacy and safety of NOACs are similar to VKAs within 3 months of surgical implantation of a BHV in those patients with AF. The noteworthy findings of the research by Magro and Sousa-Uva [7] can be summarized as follows: A D U LT C A R D IA C