Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery with an incidence of 30%. Cardiac surgery induces a postoperative inflammatory response mediated by innate immunity and associated with POAF.

Our aim is to associate the level of in vitro response of preoperative innate immunity with POAF.

An in vitro stimulation test by LPS+ATP or R848 was achieved on macrophages derived from preoperative classic monocytes, in patients hospitalized for cardiac surgery, between February and July 2022 (POMI-AF cohort NCT03376165). Then, an assay of pro-inflammatory cytokines (IL-1β, TNFα, IL-6) was carried out by ELISA method after 24hours of stimulation.

In all, 57 patients were included, whose 18 patients who presented POAF (33%). Stimulation test induces a significant increase of IL-1, TNF and IL-6 rates with LPS+ATP or R848. In the “POAF” group, a 2 times higher production of IL-1β, TNFα and IL-6 after LPS+ATP was observed, without reaching statistical significance. After stimulation with R848, we also highlight a 4 times higher production of TNFα and 2 times higher production of IL-6 in the “POAF” group, without reaching statistical significance.

Level of in vitro response of preoperative innate immunity appears to be wider after stimulation in patients with POAF after cardiac surgery, but it should be explored on a larger number of patients.