Abstract Body (Do not enter title and authors here): Background:
POAF is a prevalent complication, occurring in 30-50% of patients undergoing cardiac surgery [1]. Although women are less likely to develop this complication, women with POAF have an elevated long-term mortality rate compared to men [2]. The pathogenesis of POAF is multifactorial, with local and systemic inflammation playing key roles [3]. Resolvins mediate the active process of inflammatory resolution, which aims to terminate inflammation and restore tissue function [4]. We hypothesize that inflammatory resolution is dysregulated in patients with POAF, with a stronger association observed in female patients.

Methods:
A retrospective analysis was conducted in a cohort of 405 patients who underwent open-heart surgery with CPB. Resolvin D1 and D2 serum levels were measured in blood samples collected preoperatively, postoperatively, and daily in the ICU. Medical records were reviewed for POAF diagnosis. After exclusion of patients with longstanding AF, patients undergoing heart transplantation, and those with incomplete resolvin measurements, the analysis included 319 patients. Due to censored resolvin data and repeated measurements, a mixed-effects Tobit regression was conducted, using the statistical software “R”. The regression was adjusted for known POAF risk factors. An interaction term was used to assess whether the association between POAF and RvD1 or RvD2 levels varies by gender.

Results:
In this cohort, 51% of patients developed POAF during hospitalization, with a comparable incidence observed in male and female patients. POAF patients had significantly higher levels of RvD1 (MR:1.19, 95% CI: 1.09-1.31, p<0.001) and significantly lower levels of RvD2 (MR: 0.80, 95% CI: 0.72-0.90, p<0.001) during the perioperative period when compared to patients without POAF. The increase in RvD1 associated with POAF was 22% smaller in males than in females (p=0.012). A marginal interaction between POAF and sex was observed for RvD2, with males showing a slightly greater difference (p=0.054).

Conclusions:
The findings of our study suggest that inflammatory resolution is dysregulated in patients with POAF, marked by higher RvD1 and lower RvD2 levels. The association between POAF and RvD1 is stronger in females, indicating an exaggerated RvD1 response to POAF. Further research is needed to determine whether this sex-specific alteration in the resolution pathway contributes to the observed differences in long-term mortality between male and female POAF patients.