| Objectives: While drug-eluting stents (DES) can dramatically reduce the incidence of in-stent restenosis (ISR) and major adverse cardiac events (MACE) after percutaneous coronary intervention (PCI), the recently reported numerically higher rates of late thrombosis have been receiving extensive attention and have raised concern about the long-term efficacy and safety of the first generation DES. Regarding the factors contributing to DES late thrombosis, Virmani et al. proposed that the non-biodegradable coating polymer continuously retained on stent surfaces is one of the principal reasons resulting in localized vessel wall inflammation, hypersensitivity reactions, delayed neointimal healing, and induction of in-stent thrombosis. Additionally by multivariate analysis, Iakovou et al. reported in Journal of the American Medical Association that premature antiplatelet therapy discontinuation is one of the most important independent predictors of late in-stent thrombosis post DES implantation. At the beginning of 2007, American College of Cardiology/American Heart Association/ Society for Cardiovascular Angiography and Interventions et al. co-recommended that dual antiplatelet therapy should be prolonged to at least 12 months for patients treated with DES. However, long-term dual antiplatelet therapy is a two-edged sword which may also lead to increase the risk of hemorrhage and financial burden of patients. In order to prevent in-stent thrombosis upstream, to update the material, artwork and design of DES should be a more rational strategy. The EXCELTM sirolimus-eluting stent (JWMS, China, Registration certification NO. 2005DI3461514) uses a novel polylactic acid material which is biodegraded gradually within 3~6 months and eventually becomes water and carbon dioxide after stent implantation, thus may shorten the duration of dual antiplatelet therapy post stenting, and potentially avoid the above adverse effects, particularly local delayed neointimal healing which may induce in-stent thrombosis, caused by persistent residue of drug-carrier coating.We conducted the first prospective clinical registry soon after the EXCEL stent became available in China, to assess whether this novel DES can achieve the double optimization of reducing the incidences of both ISR, MACE and late in-stent thrombosis with 6-month dual antiplatelet regimen after stenting.Methods: One hundred consecutive hospitalized patients with coronary artery diseases exclusively treated with the EXCEL stents were prospectively enrolled. Patients with ISR lesions and acute myocardial infarction onset within 7 days were excluded. After undergoing percutaneous coronary intervention (PCI) all patients received dual antiplatelet therapy with clopidogrel (75mg/d) and aspirin (300mg/d for one month and then 100mg/d) for 6 months and then followed by aspirin alone. The primary outcome was MACE at 12 months post stenting. The secondary outcomes included binary in-stent restenosis rate measured by quantitative coronary angiography (QCA) analysis at mean 8 months post the index PCI procedure, and MACE at 30 days and 6 months.Results: All patients were successfully treated with the EXCEL stents during PCI procedure and discontinued clopidogrel at 6-month after the index procedure. Among all 153 target lesions, 127 lesions were type B2/C complex lesions (83.0%). The mean length and diameter of the target lesions were 21.6±13.3mm and 2.85±0.48mm, respectively. A total of 211 EXCEL stents were implanted with average stent number of 2.02±1.53 per patient. The mean stent length and diameter were 35.34±17.35mm and 3.23±0.46 mm, respectively. Four patients (4.0%) experienced MACE, the primary outcome by 12 months, which were 4 target-lesion revascularizations due to ISR and all done by new PCI. No death, MI, and in-stent thrombosis occurred during the 6-month aspirin treatment alone after completing 6-month dual antiplatelet therapy. QCA analysis of 112 lesions of 75 patients showed 3.6% (4/112) of in-stent restenosis and 5.4% (6/112) of in-segment restenosis. Quantitative coronary ultrasound (QCU) analysis of 64 lesions of 51 patients showed neointimal volume at the end of 8 months were 5.08±5.38mm3. Incomplete stent apposition was observed in 4 lesions (6.3%)and its occurrence did not correlate with ISR or MACE in this series. QCA and QCU analysis were performed by the independent core laboratory (Catheterization Lab, Fu Wai Hospital, Beijing, China)Conclusions: The initial registry study showed that comparison with the published data from previous pivotal studies of others drug-eluting stents, the EXCEL stent revealed similarly incidence of 12-month ISR and/or MACE for the approximate real world patients with coronary artery disease. No observed thrombosis events during the whole follow-up period revealed that the antiplatelet regimen of receiving 6-month clopidogrel treatment after EXCEL implantation was safe. After all, in-stent thrombosis are small probability events, this conclusion requires further investigation by large scale, multi-center, and longer-term follow-up clinical trials.
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