The Association of miR-29a and miR-29c with Carotid Intima–Media Thickness and Coronary Artery Disease Severity

Background/Objectives: Carotid intima–media thickness (CIMT) is widely recognized as an established biomarker of systemic atherosclerosis and coronary artery disease (CAD). Nevertheless, the connection between circulating miR-29 family members, CIMT and CAD severity has not yet been determined. The aim of this study was to investigate the association of plasma miR-29a and miR-29c with CIMT and CAD severity. Methods: A total of 628 patients scheduled for elective coronary angiography were included in the study. CAD severity was estimated using the Gensini scoring system and was classified into mild, moderate, and severe categories. Additionally, CIMT was evaluated using high-resolution B-mode ultrasonography, while plasma miR-29a and miR-29c levels were detected using qRT-PCR. Results: CIMT increased significantly with CAD severity (0.76 ± 0.15, 0.94 ± 0.18, and 1.12 ± 0.22 mm for mild, moderate, and severe CAD, respectively; p < 0.001). MiR-29a expression progressively increased, whereas miR-29c expression decreased with advancing CAD (both p < 0.001). MiR-29a correlated positively with CIMT (r = 0.612) and Gensini score (r = 0.658), while miR-29c showed negative correlations (r = −0.527 and −0.584, respectively; all p < 0.001). CIMT, miR-29a, and miR-29c were found to be independently associated with CAD severity. Their combined model demonstrated a powerful association with severe CAD (AUC = 0.927; sensitivity 88.6%; specificity 84.1%). Conclusions: Plasma miR-29a and miR-29c are independent biomarkers of CIMT and CAD severity. Their combination with CIMT can improve diagnosis of severe CAD and may enhance cardiovascular risk stratification.