certain subtypes of troponin (cardiac i and t) are 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 people with chest pain or acute coronary syndrome. a person who recently had a myocardial infarction would have an area of damaged heart muscle and elevated cardiac troponin levels in the blood. this can also occur in people with coronary vasospasm, a type of myocardial infarction involving severe constriction of the cardiac blood vessels. after a myocardial infarction troponins may remain high for up to 2 weeks.