Abstract:?Objective?To investigate the expression and significance of serum miR-145 and miR-146a in the patients with chronic obstructive pulmonary disease (COPD) and coronary heart disease (CHD).?Methods?A total of 96 patients with stable COPD admitted in our hospital during 2014 and 2019, including 38 stable COPD patients with CHD (COPD+CHD group) and 58 stable COPD patients without CHD (COPD group), were enrolled. In addition, 45 healthy persons who were examined in our hospital during the same period were selected as the control group. The expression levels of serum miR-145 and miR-146a in these patients and healthy controls were detected by the real-time fluorescence quantitative PCR (qRT-PCR), and their relationships with CRP, fibrinogen levels, lung function, blood gas indexes and Gensini score were analyzed.?Results?The levels of serum miR-145 (1.01±0.32 vs 0.73±0.25 vs 0.47±0.14) and miR-146a (0.99±0.28 vs 0.81±0.21 vs 0.45±0.13) in the control, COPD and COPD+CHD groups were decreased in turn, and there was statistical significance in the difference among them (F=47.429 and 64.532,P<0.05). The levels of serum miR-145 and miR-146a in the COPD+CHD group were negatively correlated with CRP levels (r?=-0.398 and -0.384,P<0.05), fibrinogen levels (r=-0.403 and -0.395,P<0.05) and Gensini scores (r=-0.407 and -0.413,P<0.05), and positively correlated with lung function index FEV1/FVC (r=0.421 and 0.405,P<0.05) and blood gas index PaO2?(r=0.357 and 0.362,P<0.05), respectively. In addition, the high CRP level, low PaO2?level, low FEV1/FVC level, high Gensini score, low miR-145 level and low miR-146a level were the independent risk factors of COPD complicated with CHD (P<0.05). The area under the curve (AUCROC) of serum miR-145 and miR-146 in the combination diagnosis of COPD complicated with CHD was 0.887 (95%CI:0.821-9.520), which was significantly higher than that of miR-145 and miR-146a alone.?Conclusion?The down-regulation of serum miR-145 and miR-146a is associated with decreased lung function and exacerbation of COPD, which are independent risk factors of COPD patients complicated with CHD.