Backgrounds: There is controversy whether necrotic core or fibrofatty component is associated with slow flow in patients underwent primary percutaneous coronary intervention (PPCI) and with positive remodeling. We sought to evaluate the impact of tissue component on long-term clinical events in patients underwent PPCI. Methods: The study subjects consisted of 57 consecutive patients (mean 58.5짹14.5 years old, 45 males) who underwent PPCI for acute myocardial infarction and intravascular ultrasound-virtual histology (IVUS-VH) examination. They were followed up for 27.5짹18.3months. Results: Patients with high fibrofatty volume (FFV>13.4mm³, n=29, mean 61.3 years old) had lower ejection fraction (52.7% vs. 59.4%, p=0.022), higher incidence of multi-vessel disease (69.0% vs. 28.6%, p=0.001), larger ruptured plaque cavity size (1.48mm² vs. 0.43mm², p=0.019), larger plaque area (25.7mm² vs. 15.9mm², p<0.001) and larger plaque volume (315mm³ vs. 142mm³, p<0.001) than those with low FFV (���13.4mm³, n=28, mean 55.6 years old). Patients with high FFV had significantly higher incidence (32.1% vs. 8.3%, p=0.036) of major adverse cardiovascular events (MACE, death, acute myocardial infarction, stroke, PCI) than those with low FFV. Cox regression analysis revealed that the independent factor for the MACE was only FFV (Hazard Ratio 6.748, 95% confidence interval 1.168 to 38.971, p=0.033) in this study population. When we divided the study population according to the necrotic core volume (NCV), there was no significant finding in terms of demographics and MACE. Conclusions: Plaque tissue component, especially FFV, not NCV, is important in long-term clinical outcomes in patients underwent PPCI.