Estimation of infarct size by single measurements of creatine kinase levels in patients with a first myocardial infarction

Objective Enzymatic estimation of infarct size is desirable in the reperfusion era, because a possible discrepancy with the observed asynergic area of the left ventricle may suggest the presence of stunned myocardium. Unfortunately, timely myocardial reperfusion produces a rapid washout of creatine kinase (CK) in blood flow, which overestimates infarct size. In this perspective, we investigated whether the mid-terminal portion of the CK time-activity curve could predict infarct size more reliably. Methods Enzymatic infarct size was calculated by peak CK levels, the CK area under the curve and by single CK values, in 103 patients with a first ST-elevation myocardial infarction, and compared to the left ventricular akinetic area. The wall motion asynergy score at follow-up was considered as the actual infarct size. Results In patients with peak CK within 10 h of symptom onset, CK levels at 30 h showed a high independent correlation (r(2) = 0.83; P < 0.001) with infarct size. In patients with late peak CK (> 10 h), CK levels at 12 h turned out to be the best predictor of infarct size (r(2) = 0.55; P < 0.01). At multivariate regression analysis, peak CK was the best predictor of infarct size in the whole population (r(2) = 0.61; P < 0.001). Conclusions In patients with ST-elevation myocardial infarction and early peak CK, infarct size at follow-up could be better estimated with single values of the mid-terminal portion of the CK time-activity curve. J Cardiovasc Med 7: 340-346 (C) 2006 Italian Federation of Cardiology.