Diagnosis:
Cardiac biomarkers
• The amino acid sequence for cardiac-derived troponin C is the same as that for skeletal muscle–derived troponin C. Therefore, troponin C cannot be used to distinguish between cardiac and skeletal muscle damage.
• The amino acid sequences of cardiac troponins I and T differ from those of skeletal muscle troponins I and T, respectively. Therefore, immunochemical methods can be developed that use antibodies to the cardiac-specific portions of the troponin I and troponin T molecules.
• Elevated troponin I and troponin T levels are detected in serum 4 to 6 hours after an acute myocardial infarction and can remain elevated up to 4 to 7 days afterward.
• There is a small amount of troponin I and troponin T in the cytosolic pool, which is released after an acute myocardial infarction as a result of cellular damage; this is responsible for the elevated troponin levels detected in blood 4 to 6 hours after an acute myocardial infarction.
• Troponins I and T are slowly released from the myofibril after an acute myocardial infarction; this is responsible for the sustained, elevated troponin levels seen for several days after an acute myocardial infarction.
• CK-MB is not completely cardiac specific and can also be detected in blood after skeletal muscle injury.
