Diagnostic Utility of Circulating MicroRNA-21 in Acute Myocardial Infarction

Abstract

Introduction: Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Early and accurate diagnosis is crucial for improving outcomes. Circulating microRNAs, particularly microRNA-21 (miR-21), have emerged as promising non-invasive biomarkers due to their stability in the bloodstream and involvement in myocardial injury and remodelling. This study aimed to evaluate the diagnostic utility of circulating miR-21 in AMI patients. This study aimed to evaluate the diagnostic utility of circulating     miR-21 in AMI patients.

Methods: An observational study was conducted at Mahatma Gandhi Medical College and Research Institute, India, enrolling 83 AMI patients and 30 healthy controls. Serum cardiac Troponin I (cTnI) was measured using enzyme-linked fluorescence assay, and miR-21 expression was quantified by qRT-PCR using the 2^-ΔΔCt method with U6 as an internal control. Statistical analysis included Student’s t-test, Mann–Whitney test, χ² test, Spearman correlation, and receiver operating characteristic (ROC) curve analysis to assess diagnostic performance.

Results: Circulating miR-21 levels were significantly elevated in AMI patients compared to controls (p < 0.001). ROC curve analysis showed that miR-21 discriminated AMI patients with an area under the curve (AUC) of 0.886, sensitivity of 87%, and specificity of 83% at a cut-off value of 6.5. Cardiac Troponin I demonstrated superior diagnostic accuracy (AUC = 0.990, sensitivity = 90%, specificity = 100%). A significant positive correlation was observed between miR-21 expression and Troponin I levels (r = 0.576, p < 0.001), indicating that higher miR-21 levels are associated with greater myocardial injury.

Conclusions: Circulating miR-21 is significantly upregulated in AMI patients and shows good diagnostic performance, correlating with established markers of myocardial injury. MiRNA-21 may serve as a complementary biomarker to Troponin I, enhancing early detection and risk assessment in AMI.