Background: Although early peak creatine kinase activity (peak CK) is considered a reliable marker of coronary reperfusion in patients with acute myocardial infarction (AMI), whether early peak CK indicates good myocardial salvage is unclear. Moreover, some patients have late peak CK despite successful reperfusion, and its clinical implication remains to be elucidated.
Methods and results: We examined the association of the time to peak CK with predischarge left ventricular function in 124 patients with a first AMI who had successful reperfusion within 6 hours from symptom onset. Patients were classified according to the time from reperfusion to peak CK: group A, 61 patients with peak CK < 6 hours; group B, 42 with peak CK from 6 to 12 hours; and group C, 21 with peak CK > 12 hours. There were no differences among the 3 groups in age, sex, method of reperfusion, time from symptom onset to reperfusion, collateral circulation, or the extent of risk area estimated by number of leads with ST-segment elevation. Left ventricular ejection fraction measured by predischarge left ventriculography was lowest in group A, followed by group B, and highest in group C (median values, 43%, 52%, and 60%, P < .01). Left ventricular dysfunction (left ventricular ejection fraction < or = 40%) occurred in 26 (43%) patients in group A, 8 (19%) in group B, and none in group C (P < .01).
Conclusions: We conclude that compared with early peak CK, late peak CK consistently reflects good myocardial salvage in patients with anterior AMI who had successful reperfusion within 6 hours from symptom onset.