Objectives This study sought to evaluate exact release kinetics of microRNAs (miRNAs) in acute myocardial infarction (AMI).

Background miRNAs may be useful as novel biomarkers in patients with cardiovascular disease, although it is difficult to establish the detailed release kinetics of miRNAs in patients with AMI.

Methods We analyzed the release kinetics of circulating cardiac-specific (miR-21, miR-208a) and muscle-enriched (miR-1, miR-133a) miRNAs using the TaqMan polymerase chain reaction in patients with hypertrophic obstructive cardiomyopathy who were undergoing transcoronary ablation of septal hypertrophy (TASH), a procedure mimicking AMI. Consecutive patients (n = 21) undergoing TASH were included. Serum samples were collected prior to and at 15, 30, 45, 60, 75, 90, and 105 min and 2, 4, 8, and 24 h after TASH.

Results Circulating concentrations of miR-1 were significantly increased (>3-fold; p = 0.01) after 15 min, with a peak after 75 min (>60-fold; p < 0.001). The miR-21 concentrations were not increased at any time point. Concentrations of miR-133a were significantly increased at 15 min (2.9-fold; p < 0.001) and reached a plateau between 75 and 480 min (>50-fold change). The miR-208a concentrations were elevated at 105 min (>2-fold; p = 0.01), without a further increase.

Conclusions miR-1, miR-133a, and miR-208a were continuously increased during the first 4 h after the induction of MI. In particular, miR-1 and miR-133a were significantly increased at early time points. These results demonstrate the release kinetics of miRNAs, which are helpful for developing their potential use as biomarkers in patients with acute coronary syndromes. (C) 2013 by the American College of Cardiology Foundation