Decreased gene expression of fatty acid binding protein 3 in the atrium of patients with new onset of atrial fibrillation in cardiac perioperative phase

Background: Post-operative atrial fibrillation (POAF) frequently occurs after cardiac surgery. However, the mechanisms of POAF have not been fully elucidated. We aimed to examine whether pre-operative atrial gene expression related to cardiac metabolism is changed in patients with POAF. Methods: Right atrial tissue was obtained during surgery from 38 patients who underwent cardiac surgery from 2013 to 2015. Atrial expression levels were determined by reverse transcription polymerase chain reaction for the following genes: glucose transporter type 4, peroxisome proliferator-activated receptor-α, fatty acid translocase, carnitine palmitoyltransferase 1B, and fatty acid binding protein 3 (FABP3). To investigate fatty acid β-oxidation and tricarboxylic acid cycle capacities in the mitochondria, β-hydroxyacyl CoA dehydrogenase and citrate synthase activity levels were spectrophotometrically determined. Results: POAF within 7 days after surgery was observed in 18 (47%) patients. POAF patients were significantly older, had a larger left atrial diameter, and had reduced expression of FABP3, a fatty acids transport gene in the cytosol, compared to those in the non-POAF group. Reduced FABP3 expression predicted POAF independent of age and atrial size. In contrast, fatty acid β-oxidation enzymatic activity was comparable between the groups. Conclusions: FABP3 gene expression in the atrium was reduced in patients with POAF. These findings suggest a potential link between altered fatty acid transport in the atrium and increased AF onset after cardiac surgery