Despite the proven superiority of sirolimus-eluting stents(SESs) compared with bare stents in the first year after implantation, long-term outcomes of patients treated with these novel devices remain unknown. Our goal was to evaluate the clinical, angiographic, and intravascular ultrasound(IVUS) outcomes of patients treated with SESs 4 years after implantation. Methods and Results-The study included 30 patients treated with sirolimus-eluting Bx Velocity stenting(slow release[SR; n=15] and fast release[FR; n=15]). Twenty-six patients underwent 4- year angiographic and IVUS follow-up and had matched assessments at all time points(index and 4- , 12- , 24- , and 48- month follow-up). One death occurred during the study period in a patient with a patent SES. There were no target-vessel revascularizations or thromboses between 2- and 4- year follow-up examinations. There was no stent thrombosis, target-lesion revascularization, death, or myocardial infarction in the SR group up to 4 years. Cumulative event-free survival rate was 87% for the total population(80% in the FR group and 93% in the SR group). In-stent late loss was slightly greater in the FR group(0.41± 0.49 mm) than the SR group(0.09± 0.23)after 4 years. One patient in the FR group had a 52% in-stent restenosis lesion. Percent neointimal hyperplasia volume, as detected by IVUS, remained minimal after 4 years(FR=9.1% and SR=5.7% ). Conclusions-This study confirms the longevity of the optimal outcomes observed in patients treated with sirolimus-eluting Bx Velocity stents 4 years after implantation. In-stent lumen dimensions remained essentially unchanged at 4-year follow-up, particularly in the population treated with the currently available SES(SR formulation). Despite the proven superiority of sirolimus-eluting stents (SESs) compared with bare stents in the first year after implantation, long-term outcomes of patients treated with these novel devices remain unknown. Our goal was to evaluate the clinical, angiographic, and intravascular ultrasound (IVUS) outcomes of patients treated with SESs 4 years after implantation. Methods and Results-The study included 30 patients treated with sirolimus-eluting Bx Velocity stenting (slow release [SR; n = 15] and fast release [FR; n = 15 ]) Twenty-six patients underwent 4-year angiographic and IVUS follow-up and had matched assessments at all time points (index and 4-, 12-, 24-, and 48- month follow-up). One death occurred during during the study period in a patient with a patent SES. There were no target-vessel revascularizations or thromboses between 2- and 4-year follow-up examinations. There was no stent thrombosis, target-lesion revascularization, death, or myocardial infarction in the SR group up to 4 years. C Umulative event-free survival rate was 87% for the total population (80% in the FR group and 93% in the SR group). In-stent late loss was slightly greater in the FR group (0.41 ± 0.49 mm) than the SR One patient in the FR group had a 52% in-stent restenosis lesion. Percent neointimal hyperplasia volume, as detected by IVUS, remained minimal after 4 years (FR = 9.1% and SR = 5.7 %). Conclusions-This study confirms the longevity of the optimal outcomes observed in patients treated with sirolimus-eluting Bx Velocity stents 4 years after implantation. In-stent lumen dimensions treated with the currently available SES (SR formulation).