| dc.description.abstract | Background: Elevated plasma/serum troponin, indicating perioperative myocardial injury (PMI), is common after non-cardiac surgery. However, underlying mechanisms remain unclear. Acute coronary syndrome (ACS) is associated with the early appearance of circulating microRNAs, which regulate post-translational gene expression. We hypothesised that if PMI and ACS share pathophysiological mechanisms, common microRNA signatures should be evident. Methods: Nested case-control study of samples obtained before and after non-cardiac surgery from patients enrolled in two prospective observational studies of PMI (postoperative troponin I/T>99th centile). In cohort one, serum microRNAs were compared between patients with/without PMI, matched for age, gender and comorbidity. Real-time polymerase chain reaction quantified relative microRNA expression (cycle quantification threshold <37) before and after surgery for microRNA signatures associated with ACS, blinded to PMI. In cohort two, we analysed (EdgeR) microRNA from plasma extracellular vesicles using next-generation sequencing (Illumina HiSeq500). microRNA-messenger RNA-function pathway analysis was performed (DIANA miRPath v3.0/TopGO). Results: MicroRNA were detectable in all 59 patients (median age:67yrs (61-75); 42% male), who had similar clinical characteristics independent of developing PMI. In cohort one, PMI was not associated with increased serum microRNA expression levels after surgery (hsa-miR-1-3p mean fold-change (FC): 3.99 (95%CI:1.95-8.19); hsa-miR-133-3p FC:5.67(95%CI:2.94-10.91); p<0.001). hsa-miR-208b-3p was more commonly detected after PMI (odd ratio (OR):10.0 (95%CI:1.9-52.6); p<0.01). Bioinformatic analysis of differentially expressed microRNAs from cohorts one and two identified pathways associated with adrenergic stress involving calcium dysregulation, rather than ischaemia. Conclusions: Circulating microRNAs synonymous with cardiac ischaemia were universally elevated in patients after surgery, independent of developing myocardial injury. | en_US |
