In ACS, local (serum) MRP8/14 levels (22.0 [16.2−41.5] mg/L) were increased when compared with systemic levels [13.4 (8.1−14.7) mg/L, p = 0.03]. Systemic levels of MRP8/14 were markedly elevated [15.1 (12.1−21.8) mg/L, p = 0.001] in ACS when compared with stable CAD (4.6 [3.5−7.1] mg/L) or normal controls (4.8 [4.0−6.3] mg/L). Using a cut‐off level of 8 mg/L, MRP8/14 but not myoglobin or troponin, identified ACS presenting within 3 h from symptom onset. Here, MB is linked to coronary artery disorder.