The clinical value of circulating miR-99a in plasma of patients with acute myocardial infarction.

OBJECTIVE: Acute myocardial infarction (AMI) contributes to be a significant public health problem, and it is the leading cause of morbidity and mortality in the world. However, the molecular mechanisms underlying AMI is poorly known. The purpose of this study was to investigate the change of plasma microRNA-99a (miR-99a) level in AMI patients and its potential clinical value.

PATIENTS AND METHODS: Plasma samples from 54 patients with AMI and 30 healthy volunteers were collected. Quantitative real-time PCR (qPCR) and ELISA assays were used to detect the expression of circulating plasma miR-99a and of cardiac troponin I (cTnI)/creatine kinase-MB (CK-MB), respectively. AMI patients were categorized into subgroups according to the number of stenosed coronary vessels, and the association between the plasma miR-99a level and the severity of AMI was analyzed. The expression level of miR-99a was also evaluated in patients receiving percutaneous coronary intervention (PCI).

RESULTS: The expression of miR-99a was significantly downregulated in patients with AMI compared with the normal controls (p < 0.01).  In the AMI patients, miR-99a level had a negative correlation with cTnI level (r = -0.8202, p < 0.01) and CK-MB (r = -0.6924, p < 0.01). Also, the expression of miR-99a was markedly lower in patients with more stenosed coronary vessels (p < 0.01). The relative expression level of miR-99a in AMI patients was significantly increased after receiving PCI (p < 0.01).

CONCLUSIONS: The expression level of plasma miR-99a was remarkably reduced following AMI and closely associated with the severity of AMI. Therefore, it was a promising novel diagnostic biomarker for AMI.