RESEARCH ARTICLE Circulating MicroRNAs Characterizing Patients with Insufficient Coronary Collateral Artery Function

Background Coronary collateral arteries function as natural bypasses in the event of coronary obstruc-tion. The degree of collateral network development significantly impacts the outcome of patients after an acute myocardial infarction (AMI). MicroRNAs (miRNAs, miRs) have arisen as biomarkers to identify heterogeneous patients, as well as new therapeutic targets in car-diovascular disease. We sought to identify miRNAs that are differentially expressed in chronic total occlusion (CTO) patients with well or poorly developed collateral arteries. Methods and Results Forty-one CTO patients undergoing coronary angiography and invasive assessment of their coronary collateralization were dichotomized based on their collateral flow index (CFI). After miRNA profiling was conducted on aortic plasma, four miRNAs were selected for vali-dation by real-time quantitative reverse transcription polymerase chain reaction in patients with low (CFI<0.39) and high (CFI>0.39) collateral artery capacity. We confirmed signifi-cantly elevated levels of miR423-5p (p<0.05), miR10b (p<0.05), miR30d (p<0.05) an