A Preliminary Study of microRNA-208b after Acute Myocardial Infarction: Impact on 6-Month Survival

INTRODUCTION: miRNAs contribute to a variety of essential biological processes including development, proliferation, differentiation, and apoptosis. Circulating microRNAs are very stable and have shown potential as biomarkers of cardiovascular disease. microRNA-208b expression was increased in the blood of patients with acute myocardial infarction (AMI) and has been proposed as a biomarker for early diagnosis. In this pilot study, we investigate the potential of circulating miR-208b as a prognostic biomarker of 6-month survival in AMI patients. METHODS: Plasma samples from 21 patients and 8 age- and gender-matched healthy adults were collected, and circulating levels of miR-208b were detected using quantitative real-time PCR. RESULTS: miR-208b levels were higher in healthy control subjects (9.6-fold; P ≤ 0.05). Within the AMI patients, the levels of miR-208b were significantly lower in the survivor versus nonsurvivor group (fold change = 6.51 and 14.1, resp.; P ≤ 0.05). The Kaplan-Meier curve revealed that the 6-month survival time was significantly higher among AMI patients with a relative expression of miR-208b lower than 12.38. The hazard ratio (HR) for the relative expression of miR-208b (<12.38 was the reference) was 5.08 (95% CI: 1.13–22.82; P = 0.03). CONCLUSION: Our results showed that elevated miR-208b expression was associated with reduced long-term survival in AMI patients. These pilot data indicate the need for a large follow-up study to confirm whether miR-208b can be used as a predictor of 6-month survival time after AMI.