Circulating miR-16-5p and miR-21-5p in the early post-acute interval of acute myocardial infarction: phase-specific expression and early clinical assessment

Background microRNAs show dynamic responses after acute myocardial infarction (AMI). The early post-acute interval (24–48 h after symptom onset) represents a transition from acute injury to early inflammatory signaling and constitutes a clinically relevant interval in which ventricular function and clinical stability are commonly reassessed. This study evaluated the discriminatory profile of circulating miR-16-5p and miR-21-5p during the early post-acute interval and examined their relationship with early ventricular function and clinical stability. Methods This cross-sectional study included 60 AMI patients and 30 healthy controls. Plasma miR-16-5p and miR-21-5p were quantified during 24–48 h post AMI using qRT-PCR and normalized to miR-103 as the endogenous control. Relative expression was calculated using the 2^–ΔΔCt method. LVEF and clinical stability were assessed during the same interval. Results Both miR-16-5p and miR-21-5p were significantly elevated in AMI patients compared with controls ( p = 0.003 and p < 0.001, respectively). Receiver operating characteristic (ROC) analysis demonstrated a strong discriminatory accuracy for miR-21-5p (AUC = 0.88, 95% CI 0.80–0.95) and a modest accuracy for miR-16-5p (AUC = 0.73, 95% CI 0.62–0.83). Neither microRNA showed a significant association with LVEF or clinical stability ( p > 0.05). Conclusion miR-16-5p and miR-21-5p are significantly elevated during the early post-acute interval of AMI, reflecting a distinct phase-specific molecular profile. miR-21-5p showed stronger discriminatory differences than miR-16-5p, indicating a more robust molecular signal during this phase. The absence of associations with LVEF or short-term clinical status suggests that these microRNAs reflect ongoing molecular activity rather than early functional impairment, with limited utility for early clinical risk assessment.