Circulating Preoperative Microrna-29, Biomarkers Of Collagen Synthesis, And Age Predictive Of Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting

Background: Postoperative atrial fibrillation (PoAF) is a common complication occurring in 35-50% patients within 2-3 days after cardiac surgery. Identification of patients, especially those with no prior history of atrial fibrillation before surgery, is a challenge. A pre-existing atrial substrate appears to be an important factor in the development of PoAF. The aim of this study was to assess the role of biomarkers in identifying patients at risk of PoAF in a pathophysiology-based risk predictive model by combining clinical and biochemical risk factors. Methods: Preoperative blood from patients undergoing cardiac surgery with no previous history of AF was assessed for circulating levels of biomarkers reflecting collagen synthesis/degradation and extracellular matrix remodeling using ELISA. Reverse transcriptase polymerase chain reaction assessed microRNA29 in the serum and correlated to extent of atrial fibrosis. Echocardiographic evaluation of LA mechanics was performed preoperatively using M-mode, 2D Doppler, and 3D Speckle tracking. Results: Out of 55 patients, 31 patients (56.4%) who developed PoAF after surgery during their hospital stay were older in age (70.0 ± 4.0 years vs.63.4±9.9; p<0.01) with abnormal global longitudinal stain (6.9±0.69 vs.10.9±0.93, p=0.007), higher amino-terminal peptide procollagen III (PIIINP) levels (101.1±42.7 vs.36.6±20.0; p=0.043) with increased collagen to myocardial ratio (0.20±0.09 vs. 0.09±0.01, p= 0.026), and reduced preoperative circulating microRNA-29a, -29b and -29c levels. By combining the clinical risk factors, circulating biochemical and molecular biomarkers, we developed a model that identified PoAF patients (AUC=0.7987; 95% CI, 0.6174—0.98) with reduced preoperative atrial ejection fraction (32±2% vs. 42±2 %; p=0.01) as an independent risk factor for PoAF. Conclusion: Our study developed a noninvasive tool to identify those who are at risk for new-onset PoAF in patients with no previous history of AF when combining age, biomarkers of collagen synthesis and microRNA-29a.