Inflammation and Postoperative Atrial Fibrillation in Cardiac Surgery

Postoperative Atrial Fibrillation (POAF) after Cardiac Surgery Postoperative atrial fibrillation is a common complication following cardiac surgery, characterized by irregular and often rapid heart rate. It is associated with increased morbidity, prolonged hospital stays, and higher healthcare costs. The pathophysiology of POAF is complex and multifactorial, involving atrial structural and electrical remodeling, inflammation, and autonomic dysregulation.

Inflammation and Epicardial Fat Inflammation plays a significant role in the development of POAF. Surgical trauma and cardiopulmonary bypass trigger a systemic inflammatory response, releasing cytokines and other inflammatory mediators. Epicardial fat, the visceral fat depot around the heart, is an active endocrine organ secreting pro-inflammatory cytokines and adipokines. Increased epicardial fat thickness is associated with higher levels of inflammation and has been implicated in the pathogenesis of atrial fibrillation.

RNA isolation and sequencing RNA sequencing (RNA-seq) can be used to investigate gene expression in epicardial fat in several impactful ways. RNA-seq can profile gene expression to identify active genes in epicardial fat and their expression levels, revealing key genes involved in inflammation and metabolism. By comparing gene expression between groups, such as patients with and without POAF, RNA-seq can identify differentially expressed genes associated with atrial fibrillation.

RNA-seq analyses The RNA sequencing data files were aligned to the hg38 reference genome using the Spliced Transcripts Alignment to a Reference (STAR) aligner and read counts in genes were quantified. The resulting data matrix with unnormalized counts was loaded into RStudio together with patient metadata information (e.g., age, gender, BMI, smoking). Differential expression analyses were conducted with DESeq2 using adjustment for different variables, including type of tissue, age of patients, gender, and BMI.

Hypothesis The hypothesis that POAF may be influenced by pre-existing inflammation in epicardial fat, in addition to the inflammation caused by surgical trauma.