Pericardial Fluid Biomarkers as Early Predictors for Postoperative Atrial Fibrillation—A Systematic Review

(1) Background: Postoperative atrial fibrillation (POAF) is one of the most common complications of cardiac surgery, frequently occurring in the first 2–4 days after surgery. With a variable incidence depending on the type of surgery, research in recent years has focused on identifying predisposing factors with the aim of correcting them and thus decreasing the risk of cardiovascular and total morbidity and mortality. The analysis of pericardial fluid allowed the identification of biomarkers (interleukin-6, mitochondrial DNA, myeloperoxidase or natriuretic peptides) whose presence postoperatively was associated with increased risk of POAF. (2) Materials and Methods: We conducted a search on EMBASE and PubMed and identified 75 articles, of which 10 entered the final analysis. (3) Results: Patients who develop POAF accumulate large amounts of interleukin 6, mitochondrial DNA, myeloperoxidase, or secondary atrial natriuretic peptide as a consequence of the associated inflammatory status, atrial remodeling, or disturbance of homeostasis of various ions. There are also observations that their levels in the pericardium correlate with blood levels, but further studies on larger cohorts of patients are needed to provide new evidence in this regard. (4) Conclusions: Early recognition of patients at risk of developing POAF based on easy-to-dose and easy-to-use biochemical biomarkers, whose association with POAF has been demonstrated so far in small cohorts of patients, has both therapeutic and prognostic implications, which justifies further research on large cohorts of patients.