The predominant isoenzyme of LDH in the cardiac muscle is

Lactate dehydrogenase (LDH) is a tetrameric enzyme consisting of two monomer types: H (for hea) and M (for muscle) that combine to yield five LDH isozymes: HHHH (I1), HHHM (I2), HHMM (I3), HMMM (I4), and MMMM (I5).Isozyme I1 predominates in hea tissue and isozyme I5 in the liver. Thus, when LDH levels rise in blood plasma, the identity of the injured tissue can be inferred from its characteristic pattern of LDH isozymes.In normal plasma LDH-2 is more in concentration than LDH - 1.In myocardial infarction level of LDH - 1 increases and this leads to the altered ratio of LDH.It means LDH - 1 > LDH - 2.This altered ratio of the LDH is known as a flipped pattern.Ref: Harper; 30th edition; Page no 69