Characteristics of creatine kinase-MB and MB isoforms in serum after reperfusion in acute myocardial infarction

Characteristics of CK-MB, the MB1 and MB2 isoforms, and the MB2/MB1 ratio are described in six acute myocardial infarction (AMI) patients in whom the infarct-related artery was identified and, after intervention, normal coronary flow was re-established. After myocardial reperfusion, washout of CK-MB and the MB2 isoform occurred in parellel, with CK-MB peaking between 5.75 and 10.0 h, and MB2 peaking between 4.50 and 8.00 h. In five of the six patients, MB1 peaked between 8.75 and 15.5 h; the MB2/MB1 ratio demonstrated the earliest peak from 0.75 to 2.25 h. When we compard this study group to an additional 10 AMI patients who had achieved myocardial reperfusion earlier, we found a significant difference (P < 0.005) for all tests, except MB1 isoform activity, as early as 50 min after reperfusion. This same comparison, by logistic-regression analysis, showed that the MB2/MB1 ratio discriminated between the groups 50 min after reperfusion (P < 0.05); MB2 showed near-significance at 100 min (P < 0.057); and CK-MB achieved significance after 200 min (P < 0.05). CK-MB, the MB2 isoform, and especially the MB2/MB1 ratio show potential for the early, noninvasive detection of myocardial reperfusion.