BACKGROUND: The impact of tissue prolapse (TP) on clinical outcomes after stent implantation is still not well known. OBJECTIVES: We used intravascular ultrasound (IVUS) to evaluate the association of TP with short- and long-term clinical outcomes after stent implantation in 418 acute myocardial infarction (AMI) patients (155 ST segment elevation and 263 non-ST segment elevation MI). METHODS: TP was defined as tissue extrusion through the stent strut at post-stenting. We evaluated the incidences of stent thrombosis, no-reflow, and long-term clinical outcomes. RESULTS: After stenting, TP was detected in 34% without difference according to the stent types. Acute and subacute stent thrombosis occurred more frequently in patients with TP compared with those without TP (3.5% vs. 0.7%, p=0.035, and 4.2% vs. 0.7%, p=0.013, respectively). However, no significant difference was observed in the incidence of late stent thrombosis between both groups. No-reflow was developed more frequently in patients with TP compared with those without TP (25.4% vs. 9.8%, p<0.001). Creatine kinase-MB (+9.0±25.2 U/l vs. -4.2±41.6 U/l, p=0.001) and cardiac specific troponin-I (+10.0±43.5 ng/ml vs. -1.2±35.6 ng/ml, p=0.005) were elevated more significantly after stenting in patients with TP compared with those without TP. There were no significant differences in the incidences of cardiac death, MI, and target vessel revascularization at 1-year. Multivariate analysis showed that TP was the independent predictor of composite of acute and subacute stent thrombosis [odds ratio (OR)=4.211; 95% CI 1.198-14.805, p=0.025] and composite of acute stent thrombosis and no-reflow (OR=2.551; 95% CI 1.315-4.952, p=0.006). CONCLUSIONS: TP was associated with short-term complications (acute and subacute thrombosis and no-reflow phenomenon), however it was not affect long-term clinical outcomes after stent implantation in patients with AMI.