The investigators aim to evaluate circulating irisin levels alterations in patients with acute myocardial infraction and in patients with coronary artery disease subjected to percutaneous coronary intervention.

Irisin is a newly discovered myokine induced in exercise. There is evidence that cardiac muscle produces more irisin than skeletal muscle in response to exercise. Furthermore, irisin has been associated with isoproterenol-induced myocardial infarction (MI) in rats while it has been reported to decrease after acute myocardial infarction in humans. The investigators aim 1) to investigate circulating irisin levels in patients at the time of acute myocardial infarction and after reprefusion \[primary percutaneous coronary intervention (PCI)\] 2) to compare irisin' s diagnostic and prognostic value and specificity value in myocardial infarction with known markers of cardiac injury such as creatine kinase-MB isoenzyme (CK-MB) and troponin 3) to evaluate irisin as an early necrosis biomarker 4) To evaluate irisin's sensitivity as a biomarker to detect minor myocardial necrosis after elective percutaneous coronary intervention