Comparison of enzymatic and anatomic estimates of myocardial infarct size in man.

Abstract

Enzymatic estimates of myocardial infarct size based on plasma levels of MB creatine kinase (MB-CK) were compared with anatomic infarct size in 49 human hearts obtained at autopsy. The patients studied were enrolled in the Multicenter Investigation of Limitation of Infarct Size (MILIs) study program within 18 h of the onset of acute infarction and were treated at 1 of 5 participating hospitals. Infarct size was estimated from serial measurements of plasma MB-CK made at the core laboratory for CK analysis. Hearts obtained at autopsy were studied independently by the core pathology laboratory without knowledge of the MB-CK levels or clinical results. Data from the 2 laboratories were compared at the data coordinating center. Of 49 hearts, 12 were excluded either because anatomic infarct size could not be established or because the infarct occurring at the time of enrollment in the MILIS study could not be distinguished with certainty from other infarcts. Of the remaining 37 hearts, peak MB-CK level was available in 36, but samples sufficient for estimation of infarct size were available only 25. The overall correlation coefficient (Spearman) was 0.87 for these 25 hearts, indicating the enzymatic estimates of infarct size correlate closely with anatomic measurements. CK estimates of myocardial infarct size evidently represent a valid clinical end point for assessing myocardial infarct size, and the effect of therapy thereon, in groups of treated and control patients.