Background: Coronary artery occlusion does not always manifest with ST-elevation, and some patients can have patent coronary vessel.

Aim: We evaluated circulating microRNA (miRNA) profiles to discriminate subjects with infarct-related artery (IRA) occlusion.

Methods and results: Patients (n = 43) with uncomplicated acute coronary syndrome and positive troponins were classified with respect to patent vs. occluded IRA or ST-elevation vs. non-ST elevation MI (STEMI vs. NSTEMI). Expression levels of serum miRNAs (miR-1, -16, -34a, -122, -124, -208b, -133a/b, -375, and -499) were analysed. Out of 16 STEMI and 27 NSTEMI patients, IRA occlusion was noted in 12 and 15 patients, respectively. The remaining four STEMI and 12 NSTEMI patients had patent IRA. STEMI patients had higher troponin T levels and a 3.83-fold higher miR-134 expression (p < 0.025). Patients with the occluded vs. patent IRA had higher levels of miR-133a (fold change: 7.00), miR-133b (4.57), miR-34a (5.50), miR-124 (2.55), and miR-134 (3.45) but no difference in troponin T levels. Receiver operator characteristic analysis identified decision-making miRNAs in occluded vessels: miR-124 (AUC: 0.787, p < 0.001), miR-133b (AUC: 0.704, p = 0.006), and miR-134 (AUC: 0.686, p = 0.016). With respect to STEMI, only miR-134 showed a discriminating value (AUC: 0.725, p = 0.002).

Conclusions: The degree of IRA occlusion determines circulating miRNA expression, and specific miRNAs may be useful in indicating patients requiring urgent coronary revascularisation.