A determination of the frequency and magnitude with which postoperative myonecrosis occurs has been difficult. In 2007, the European Society of Cardiology/ ACCF/AHA/World Heart Federation Task Force for the Redefinition of Myocardial Infarction stated, [B]iomarker values more than 5 times the 99th percentile of the normal reference range during the first 72 h following CABG, when associated with the appearance of new pathological Q-waves or new [left bundle branch block], or angiographically doc- umented new graft or native coronary artery occlusion, or imaging evidence of new loss of viable myocardium should be considered as diagnostic of a CABG-related myocardial infarction (type 5 myocardial infarction). 203, p. 2183 Until 2000, the conventional biomarker for myonecrosis was cre- atine kinase-MB, but at present cardiac-specific troponin is the preferred indicator of myonecrosis.198,200 The higher the serum concentrations of biomarkers after CABG, the greater the amount of myonecrosis and, therefore, the greater the likelihood of an adverse outcome. Published data from the PREVENT IV trial suggest, first, that serum biomarkers for myonecrosis are elevated postop- eratively even in roughly 10% of CABG subjects who are considered to be low risk for the procedure and, second, that short-term (30-day) and long-term (2-year) outcomes were worse in these patients than in those without a postoperative biomarker elevation. Similarly, a direct correlation has been noted between the presence and magnitude of biomarker elevations postoperatively and both intermediate- and long- term risk of death.1028 5.2.4.1. Transfusion: Recommendation Class I 1. 