POAF is a common complication occurring in 20%-50% of cardiac surgery patients18–23. Episodes of POAF are often transient and follow a typical time course, peaking at 2–4 days after surgery19 and resolving within 4–6 weeks24. Nonetheless, those patients with transient POAF might frequently have AF recurrences25–27 as well as elevated risk of stroke and mortality25–27. The popularity of the left appendage clip has triggered interest of applying it in patients who are at risk of stroke and have no history of AF13. However, whether patients with no pre-operative AF may benefit from LAAC remains unknown14. The ongoing left atrial appendage closure by surgery-2 (LAACS-2) trial14 is the first study to enroll patients with and without history of AF. Results from this ongoing trial are expected to determine if the prevention of stroke events using LAAC is achievable in first-time open-heart surgery patients despite their AF status and CHA2DS2VASC score.
Because LAAC is considered a promising alternative to oral anticoagulation (OAC) therapy for preventing or decreasing the risk of stroke, most prospective and retrospective clinical studies evaluating the efficacy and safety of LAAC focused on patient populations with history of AF. Recently, the ATLAS trial was a feasibility study monitoring a subset of cardiac surgery patients for whom the risks of thromboembolic events and bleeding intersected and thus had equipoise regarding LAA management and anticoagulation limitations13. The ATLAS inclusion criteria included a CHA2DS2VASc score > = 2, encompassing 376 patients undergoing LAAC and 186 without LAAC. POAF among those who received LAAC compared to no-LAAC was (47.3 vs. 38.2%; P = 0.047). Of note, all the patient demographics and patient characteristics among LAAC and no-LAAC were not statistically significant.
Despite differences in the study design, findings from our study were in agreement with the findings from the ATLAS trial. Specifically, both studies demonstrated significant increase in the risk of new-onset POAF after cardiac surgery in patients underwent LAAC. While the ATLAS study suggested lower risk for thromboembolic events in LAAC patients with POAF, our study demonstrated non-significant lower risk of mortality and 30-day readmission in LAAC patients. Further, our results showed significant increase in hospital LOS.
Possible explanations for the increased risks of POAF following atrial clip exclusion include (but are not limited to) local atrial installation, serial pericarditis, and a reduction in atrial compliance, resulting in more effective volume in the left atrium6,13. The outcome of more POAF in those without a prior history of AF needs to be emphasized to the patient because POAF may lead to higher long-term risk of atrial fibrillation28. Given increasing understanding of implications of AF across domains (e.g., risk of heart failure), subjecting a patient without a prior history of AF to LAAC may place that patient at risk of long-term health conditions. Similarly, while the incidence of short-term complications related to LAAC is low, heart torsion, left atrial appendage bleeding, and circumflex artery pinching have been reported 29,30 .
The potential justification for performing LAAC in patients without a history of atrial fibrillation is that they will be protected from prothrombotic events if they do develop POAF and may be able to forego anticoagulation and its associated risks. It is our belief, based on the accumulated data, including the findings of our study herein, that preemptive LAAC in cardiac surgery with sinus rhythm is not justified unless future high-quality RCTs should definitively demonstrate benefits that outweigh the risk16.
The current study has limitations inherent in a small, single center, retrospective study. The small size of the participants in the LAAC group (162 patients) may have implications for the statistical power and generalizability.