Assessment of infarct size by biomarker measurement. Assessment of infarct size by biomarker measurement. Serum creatine kinase (CK) release over the first 72 h of reperfusion. Area under the curve (AUC; arbitrary units) of serum CK release was measured in control (black) and postconditioned (grey) patients. There was a significant 19% reduction in the AUC of CK release for postconditioned versus control (p=0.027). Sophie Pichot et al. Open Heart 2015;2:e000175 ©2015 by British Cardiovascular Society