Home » On the third day of onset of acute myocardial infarction the enzyme elevated is Enzymology MCQs On the third day of onset of acute myocardial infarction the enzyme elevated is January 22, 2022 13 Views Q. On the third day of onset of acute myocardial infarction the enzyme elevated is A. Serum AST B. Serum CK C. Serum LDH D. Serum ALT Answer: Serum LDH