# Characterisation of Ventricular Nucleotide Metabolism and Clinical Predictors Associated with the Onset of Atrial Fibrillation Following Cardiac Surgery

## TL;DR

This study explores how changes in heart cell energy levels and surgical factors like age and procedure time relate to the risk of developing atrial fibrillation after heart surgery.

## Contribution

The study identifies ventricular nucleotide metabolism changes and clinical predictors for postoperative atrial fibrillation following cardiac surgery.

## Key findings

- Patients who developed AF had longer cross-clamp times during CABG and AVR surgeries.
- CABG patients with AF showed significant drops in ATP/ADP and ATP/AMP ratios post-reperfusion.
- Age and cross-clamp time were the most significant clinical predictors of AF development.

## Abstract

Introduction: Postoperative atrial fibrillation (POAF) is a common complication after heart surgery, adversely impacting clinical outcomes and healthcare costs. Little is known about the dynamics of nucleotide metabolism associated with the development of POAF at a ventricular level. We conducted a post hoc trial analysis to investigate the changes in ventricular adenine nucleotides and the clinical predictors associated with the development of AF. Methods: Using data from a randomised trial, we analysed ATP/ADP, ATP/AMP, and energy charges in left and right ventricular biopsies of patients who developed AF compared to non-AF patients. A logistic regression model was used to understand the predictors associated with the development of atrial fibrillation in this cohort. Results: We analysed adenine nucleotide levels available in 88 patients who underwent coronary artery bypass grafting (CABG) (n = 65) and aortic valve replacement (AVR) (n = 23), out of which 27 (31%) developed a new onset of AF. Seventeen (43.4%) patients in the CABG group and ten (26.15%) in the AVR group developed AF. The patients who developed postoperative AF had longer cross-clamp times for CABG (p = 0.013) and AVR (p = 0.002). The most significant predictors for AF development were age (p = 0.003) and cross-clamp time (p = 0.012). In patients undergoing CABG who developed AF, we found a significant drop in post-reperfusion ATP/ADP and ATP/AMP ratios compared to pre-reperfusion. This was not significant for the patients who underwent AVR. Furthermore, the patients who underwent CABG and developed AF had higher pre- and post-reperfusion ATP/ADP ratios and energy charges than non-AF patients, suggesting a higher reserve of cardiac nucleotides. Conclusions: The development of postoperative atrial fibrillation is associated with intraoperative changes in the ventricular adenine nucleotide metabolism of patients undergoing CABG. In the clinical analysis, age and cross-clamp time were significant predictors of AF development.