Elevated plasma level of NT-proBNP has been known to associate with coronary atherosclerosis. Method. Using aspiration catheter, we collected 80 coronary blood samples at the proximal and distal ends of the culprit lesion during primary percutaneous coronary intervention(PCI) in STEMI. We measured commonly used cardiac biomarkers [CK, CK-MB, troponin-I] as well as [NT-proBNP]. VH-IVUS imaging was performed before and after stent implantation during primary PCI. The averaged plaque components were defined as volume divided by # of image slices. Results. Pt age was 57짹13 yrs and 94% were males. Greyscale IVUS showed the lesion length was 19.21짹5.60 mm, mean vessel area was 17.54짹4.86mm2, mean lumen area was 6.38짹1.77 mm2, and mean plaque area was 11.14짹3.62mm2. NT-proBNP was similar in both of proximal distal end of culprit lesion. The levels of CK, CK-MB, and troponin-I did not show any correlation with plaque composition. However, NT-proBNP was correlated with fibrotic plaque and dense calcium in intracoronary blood at the proximal end of culprit lesion. The changes of NT-proBNP between proximal and distal end of the culprit lesion (∆NT-proBNP) was correlated with average necrotic core(%) (r=0.3892, p=0.0369)(table). Conclusion. VH measured plaque components may contribute to changes of NT-proBNP in pts with STEMI.