Background Drug-eluting stents (DES) with durable polymer have significantly reduced restenosis and target vessel revascularization compared with bare metal stents.Durable polymer has been linked with persistent inflammation of vessel wall and delayed endothelial healing that may increase the risk of late and very late stent thrombosis.This study sought to evaluate the efficacy and safety of HELLOS completed biodegradable polymer sirolimus-eluting stent (SES) in de novo coronary lesions.Methods Totally,287 patients with one or two de novo coronary lesions (lesion length ≤38 mm and reference vessel diameter 2.5-4.0 mm) were enrolled in the HOPE study,a prospective,multicenter,randomized,non-inferiority trial.Patients were randomized to treatment either with HELIOS completed biodegradable polymer SES (n=142) or PARTNER durable polymer SES (n=145).The primary endpoint was angiographic in-stent late lumen loss (LLL) at 9-month follow-up.The secondary endpoint included stent thrombosis and major adverse cardiac events including cardiac death,myocardial infarction (MI) and target lesion revascularization (TLR).Results The 9-month in-stent LLL in the HELIOS group was similar to the PARTNER group,(0.16±0.22) mm vs.(0.19±0.30) mm (P=0.28).The difference and 95％ confidence interval were-0.03 (-0.09,0.04),and the P value for non-inferiority ＜0.01.Major adverse cardiovascular event (MACE) occurred in 7.9％ vs.8.2％,MI in 2.4％ vs.3.0％,TLR in 5.5％ vs.3.0％,and stent thrombosis in 0 vs.1.5％; and events were comparable between the HELIOS group and PARTNER group at three-year follow-up (all P ＞0.05).The three-year cardiac death was lower in the HELIOS group,but with no significant difference,0 vs.3.0％ (P=0.12).Conclusions In the HOPE trial,the novel completed biodegradable polymer SES HELIOS was non-inferior to the durable polymer SES PARTNER with respect to nine-month in-stent LLL in de novo coronary lesions.The incidence of other clinical endpoints was low for both of the stents in three-year follow-up.