Clinical evaluation of immunochemical assay of lactate dehydrogenase isoenzyme 1 in early detection of acute myocardial infarction.

We immunochemically measured lactate dehydrogenase isoenzyme 1 (LD-1), calculated LD-1/LD ratios (% LD-1) for 122 specimens from 60 patients, and compared the results with those for the conventional cardiac profile and other findings such as clinical presentation and electrocardiogram. Results for LD-1 and % LD-1 could be classified into three groups: group I, with LD-1 less than 64 U/L; group II, with LD-1 greater than 64 U/L and % LD-1 between 17 and 37%; and group III, with LD-1 greater than 64 U/L and 5 LD-1 greater than 38%. These three groups correlated closely and consistently with three patients of cardiac profile, i.e., those of no acute myocardial infarct, myocardial ischemia, and acute myocardial infarct, respectively.