Troponin is a protein complex which regulates the contraction of striated muscle. In acute coronary syndromes (ACS), it can be detected in blood at 4-8 hours following the onset of chest pain, has a peak concentration at 12-16 hours, and remains elevate for 5-9 days. ACS represents a continuum of increasing risk from asymptomatic coronary artery disease to myocardial ischemia and thrombus development. Patients with a very low troponin have a good short term prognosis. Troponin I has been used as a reliable marker in the diagnosis of perioperative myocardial infarction in patients undergoing cardiac surgery.