Optimal criteria for rapid detection of myocardial reperfusion by creatine kinase MM isoforms in the presence of residual high grade coronary stenosis

Analysis of isoforms of MM creatine kinase (CK) in plasma is being developed as a means for rapid detection of coronary recanalization in patients given thrombolytic agents. To determine whether flow-limiting residual stenosis typical of that seen in patients affects plasma isoform profiles, stenosis sufficient to preclude reactive hyperemia was induced in dogs before coronary occlusion, followed by recanalization in 2 h. Plasma activities of the MM CK isoform released from myocardium (MM₃) and its two conversion products elaborated sequentially (MM₂ and MM₁) were assayed in serial samples with a rapid quantitative chromatofocusing procedure. Reperfusion in 10 dogs shortened the mean intervals (±SD) to the occurrence of peak MM₃ activity (3.7 ± 0.9 h), peak MM₃ expressed as a percent of total CK activity (MM₃%, 2.5 ± 0.3 h) and the maximal ratio of MM₃ to MM₁ (2.7 ± 0.3 h) compared with results in 10 control dogs without reperfusion. Nevertheless, the appearance of these peaks was delayed by 8% to 57% when residual stenosis was present. In contrast, the rate of increase of MM₃% was delineated before the peak, was fivefold greater with recanalization (1.19 ± 0.46 versus 0.26 ± 0.11% min^-1 in control dogs) and was not attenuated by residual stenosis. Thus, this criterion appears capable of delineating recanalization early after thrombolysis whether or not high grade residual stenosis is present.