Which enzyme activity does not typically increase after an acute myocardial infarction?

Which enzyme activity does not typically increase after an acute myocardial infarction?

• A. Creatine kinase
• B. Lactate dehydrogenase
• C. Aspartate aminotransferase
• D. Alanine aminotransferase

Answer: (D)

After an acute myocardial infarction, injured heart muscle leaks enzymes that are abundant inside cardiac cells into the bloodstream. The enzymes most commonly elevated reflect myocardial content and injury: creatine kinase (especially the CK-MB isoenzyme), lactate dehydrogenase, and to some extent aspartate aminotransferase. Alanine aminotransferase, however, is primarily a liver enzyme and is not released in significant amounts from cardiac tissue. Therefore ALT activity does not typically increase after a myocardial infarction. If ALT were elevated, it would more likely indicate liver injury rather than heart muscle damage.

After an acute myocardial infarction, injured heart muscle leaks enzymes that are abundant inside cardiac cells into the bloodstream. The enzymes most commonly elevated reflect myocardial content and injury: creatine kinase (especially the CK-MB isoenzyme), lactate dehydrogenase, and to some extent aspartate aminotransferase. Alanine aminotransferase, however, is primarily a liver enzyme and is not released in significant amounts from cardiac tissue. Therefore ALT activity does not typically increase after a myocardial infarction. If ALT were elevated, it would more likely indicate liver injury rather than heart muscle damage.