A 68-year-old man with acute ST elevation myocardial infarction (STEMI) underwent emergent coronary angiography which showed total occlusion in the proximal right coronary artery (RCA). Gray-scale intravascular ultrasound (IVUS) revealed the culprit lesion was expansively remodeled and contained ruptured and echolucent plaques with spotty calcification, whereas thin-capped fibroatheroma and a large amount of scattered necrotic core were observed by virtual histology (VH)-IVUS. After stent implantation in the proximal RCA under a filter protection, filter-no-reflow phenomenon occurred and thrombus-like defect was observed in the mid RCA. Under these conditions, VH-IVUS detected a large amount of scattered necrotic core in the mid RCA. We suggest scattered necrotic core detected by VH-IVUS may be associated with slow-flow phenomenon during percutaneous coronary intervention in our patient with STEMI.