Lactate metabolism as a prognostic index in unstable angina

Fifty patients evaluated because of unstable angina were followed up for a mean period of 63.7 months. Analysis of transmyocardial lactate metabolism was performed in all patients in addition to coronary angiography and ventriculography. All patients had at least one coronary lesion of great than 75%. Although technically feasible, aortocoronary bypass surgery was not performed on initial hospitalization and all patients were treated medically. Patients were divided into two groups on the basis of lactate metabolism; group A lactate production great than 15%, group B lactate production less than 15% or lactate extraction. There was no difference in left ventricular end-diastolic pressure or ejection fraction between the two groups. A coronary score index was higher in group A than group B (5.45 +/- 2.2 vs 3.13 +/- 1.2) (p less than 0.05). The incidence of myocardial infarction was higher in group A than group B in hospital (44.4% vs. 4.3%, p less than 0.05), and long term (70.3% vs. 17.3%, p less than 0.05). Mortality was higher in group A than group B in hospital (25.9% vs. 0%, p less than 0.05) and long term (66.7% vs. 13%, p less than 0.05). Analysis of lactate metabolism thus provides a prognostic index in unstable angina which complements information obtained by coronary angiography and ventriculography.