Lactate dehydrogenase isoenzyme 1 in the diagnosis of myocardial infarction.

A new immunochemical method for the measurement of lactate dehydrogenase isoenzyme 1 (LDH-1) was used on 113 consecutively admitted patients with suspected myocardial infarction. Using WHO's criteria and our routine program 49 were classified as having myocardial infarction and 64 as having no myocardial infarction. LDH-1 was better than total lactate dehydrogenase is discriminating between patients with and without myocardial infarction (p less than 0.02), and the efficiency (the number of correct classifications divided by the total number of analyses) on day 2-3 equalled that from the literature for CK-MB on day 1. Total lactate dehydrogenase and LDH-1 are supplemental to creatine kinase (CK) and CK-MB, while aspartate aminotransferase may be omitted in the diagnosis of myocardial infarction. Determination of the ratio of LDH-l to total lactate dehydrogenase offered to no advantage.