OBJECTIVES: The purpose of the SCANDSTENT study was to evaluate the use of sirolimus-eluting stents(SES) in complex coronary lesions. BACKGROUND: The use of SES improves angiographic and clinical outcomes compared with bare-metal stents(BMS) in simple coronary artery lesions, but there is limited evidence of their safety and efficacy when implanted in complex lesions. METHODS: We randomly assigned 322 patients with symptomatic complex coronary artery disease to receive either SES or BMS. The lesions were occluded(36% ), bifurcational(34% ), ostial(22% ), or angulated(8% ) in morphology. The primary end point was the difference in minimal lumen diameter six months after stent implantation. RESULTS: The patients were well matched in terms of demographic and angiographic baseline characteristics; 18% had diabetes. The reference vessel diameter was 2.86 mm in mean, and the lesion length 18.0 mm. At follow-up, patients who received SES had a minimal lumen diameter of 2.48 mm compared with 1.65 mm in those who received BMS(p< 0.001), a diameter stenosis of 19.3% versus 43.8% (p< 0.001), and 2.0% versus 31.9% developed restenosis(p< 0.001). The rate of major adverse cardiac events was 4.3% with SES versus 29.3% with BMS(p< 0.001), and stent thrombosis was observed in 0.6% in the SES group versus 3.1% in the BMS group(p=0.15). CONCLUSIONS: The use of SES markedly reduced restenosis and the occurrence of major adverse cardiac events in patients with complex coronary artery lesions without increasing the risk of stent thrombosis.