Analyses of Creatine Kinase lsoenzymesand Isoformsin Serum to Detect Reperfusionafter Acute Myocardial Infarction1

were measured to assess reperfusion after acute myocardial infarction (AMI). In streptokinase-treated and in spontane-ously reperfused AMI patients, total CK, CK-2 activity and concentration, and CK-33 isoform activity peaked significant-ly (p <0.05) earlier than conventionally treated, non-reper-fused patients. The ratio for CK-33 to CK-31 activities peaked significantly (p <0.05) earlier in both the streptokinase-treated and spontaneously reperfused groups, and indicated a greater release of enzyme (higher ratio) than in the conventionally treated patients. The ratio of CK-33/31 also peaked significantly (p <0.05) earlier in all three groups than did total CK, CK-2, and CK-33 activitiesor concentrations. The clearance rates of total CK, CK-2, and CK-33 were not significantly different in all three groups. Thus, the ratio CK-33/1 was the earliest indicator of infarction in both reper