1) "Troponin is a complex of three regulatory proteins that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle. Discussions of troponin often pertain to its functional characteristics and/or to its usefulness as a diagnostic marker for various heart disorders." Source and further information: http://en.wikipedia.org/wiki/Troponin 2) "The troponin test can be used as a test of several different heart disorders, including myocardial infarction." "Certain subtypes of troponin (cardiac troponin I and T) are very sensitive and specific indicators of damage to the heart muscle (myocardium). They are measured in the blood to differentiate between unstable angina and myocardial infarction (heart attack) in patients with chest pain or acute coronary syndrome. A patient who had suffered from a myocardial infarction would have an area of damaged heart muscle and so would have elevated cardiac troponin levels in the blood. This can also occur in patients with coronary vasospasm. It is important to note that cardiac troponins are a marker of all heart muscle damage, not just myocardial infarction. Other conditions that directly or indirectly lead to heart muscle damage can also increase troponin levels. Severe tachycardia (for example due to supraventricular tachycardia) in an individual with normal coronary arteries can also lead to increased troponins for example, presumably due to increased oxygen demand and inadequate supply to the heart muscle. Troponins are also increased in patients with heart failure, where they also predict mortality and ventricular rhythm abnormalities. They can rise in inflammatory conditions such as myocarditis and pericarditis with heart muscle involvement (which is then termed myopericarditis). Troponins can also indicate several forms of cardiomyopathy, such as dilated cardiomyopathy, hypertrophic cardiomyopathy or (left) ventricular hypertrophy, peripartum cardiomyopathy, Takotsubo cardiomyopathy or infiltrative disorders such as cardiac amyloidosis. Heart injury with increased troponins also occurs in cardiac contusion, defibrillation and internal or external cardioversion. Increased troponins are commonly increased in several procedures such as cardiac surgery and heart transplantation, closure of atrial septal defects, percutaneous coronary intervention or radiofrequency ablation." Source and further information: http://en.wikipedia.org/wiki/Troponin_test 3) "The diagnosis of myocardial infarction is made by integrating the history of the presenting illness and physical examination with electrocardiogram findings and cardiac markers (blood tests for heart muscle cell damage). A coronary angiogram allows visualization of narrowings or obstructions on the heart vessels, and therapeutic measures can follow immediately. At autopsy, a pathologist can diagnose a myocardial infarction based on anatomopathological findings. A chest radiograph and routine blood tests may indicate complications or precipitating causes and are often performed upon arrival to an emergency department. New regional wall motion abnormalities on an echocardiogram are also suggestive of a myocardial infarction. Echo may be performed in equivocal cases by the on-call cardiologist. In stable patients whose symptoms have resolved by the time of evaluation, technetium-99m 2-methoxyisobutylisonitrile (Tc99m MIBI) or thallium-201 chloride can be used in nuclear medicine to visualize areas of reduced blood flow in conjunction with physiologic or pharmocologic stress. Thallium may also be used to determine viability of tissue, distinguishing whether non-functional myocardium is actually dead or merely in a state of hibernation or of being stunned. - Diagnostic criteria: WHO criteria have classically been used to diagnose MI; a patient is diagnosed with myocardial infarction if two (probable) or three (definite) of the following criteria are satisfied: 1. Clinical history of ischaemic type chest pain lasting for more than 20 minutes 2. Changes in serial ECG tracings 3. Rise and fall of serum cardiac biomarkers such as creatine kinase-MB fraction and troponin The WHO criteria were refined in 2000 to give more prominence to cardiac biomarkers. According to the new guidelines, a cardiac troponin rise accompanied by either typical symptoms, pathological Q waves, ST elevation or depression or coronary intervention are diagnostic of MI." Source and further information: http://en.wikipedia.org/wiki/Myocardial_infarction#Diagnosis