Well the levels and changes in blood enzyme and troponin levels are better explained in this picture: https://hpsanatomy6.wikispaces.com/Gabriella+and+Jasmine We should remember that enzymes are the ones who regulate chemical reactions in the heart, specialy the cardiac enzymes. Cardiac enzyme studies measure the levels of enzymes and proteins that are linked with injury of the heart muscle. These include the enzyme creatine kinase (CK), and the proteins troponin I (TnI) and troponin T (TnT).
Troponin level can be measured after several hours of heart attack. However if troponin level is measured just after heart attack , it will look a like normal. The same is the case with cardiac enzyme.
