Long-term outcomes of new-generation coronary stents in China

Yaling Han, Editor-in-Chief, reviews two highly interesting papers published in The Chinese Journal of Cardiology. Coronary artery disease (CAD) is one of the major global health care and economic burdens. Since percutaneous coronary intervention (PCI) began with balloon angioplasty in 1977, it has more recently been considered that PCI with drug-eluting stents (DES) implantation is the most commonly employed treatment option for patients with CAD.1 As time has progressed, there have been exciting technological advancements in the field, including several new-generation DES with thinner stent struts, new anti-proliferative agents, biodegradable polymer (BP) coating, and even bioabsorbable stents for better clinical outcomes.2,3 However, complications, such as in-stent restenosis, late thrombosis, local chronic inflammation, and re-occlusion, are still problems of DES implantations, meaning that deep analysis of their long-term stability and failure mechanisms is necessary. This was recently reported in the CJC with a contribution entitled ‘Five-year clinical outcomes of the second-generation biodegradable polymer sirolimus-eluting stent (EXCROSSAL) in treating patients with de novo coronary lesions’ by Prof. Yaling Han and colleagues from the General Hospital of Northern Theater Command.4 CREDIT II was a randomized trial comparing the EXCROSSAL vs. EXCEL stents [durable polymer (DP) sirolimus-eluting stents] in patients with up to two de novo coronary lesions, and CREDIT III was a prospective, single-arm study evaluating the efficacy and safety of EXCROSSAL in broad types of de novo coronary artery lesions. From November 2013 to December 2014, 833 CAD patients, including 579 males (69.5%) with average age (59.3 ± 9.1) years and implanted with EXTROSSAL stents in CREDIT II and III trials, were selected from 33 centres in China. Clinical outcomes are summarized in Table 1. The incidences of target lesion failure (TLF) and patient-oriented composite endpoint [PoCE, including all-cause death, all myocardial infarction (MI), or any revascularization] in the 5-year follow-up were 10.6% (86/811) and 15.5% (126/811), respectively. The rate of individual TLF components in the 5-year analysis was 1.4% for cardiac death, 5.7% for target vessel MI, and 5.5% for ischemia-driven target lesion revascularization. Stent thrombosis (ST) occurred in 1.0% (8/811) of patients. Univariate Cox regression analysis showed that vessel diameter ≤2.74 mm (HR = 3.20, 95% CI 1.90–5.39, P < 0.001), lesion length ≥16.7 mm (HR = 1.88, 95% CI 1.18–2.99, P = 0.007), and multivessel disease (HR = 2.44, 95% CI 1.60–3.72, P < 0.001) were related factors of TLF within 5 years after PCI. The 5-year follow-up analysis of EXCROSSAL Values are presented as n (%). Target lesion failure was defined as a composite of cardiac death, target vessel MI, or ischemia-driven TLR. Patient-oriented composite endpoint was defined as a composite of all-cause death, all MI, or any revascularization. ID-TLR, ischemia-driven target lesion revascularization; MI, myocardial infarction; PoCE, patient-oriented composite endpoint; ST, stent thrombosis; TLF, target lesion failure; TLR, target lesion revascularization; TVMI, target vessel myocardial infarction; TVR, target vessel revascularization. The 5-year follow-up analysis of EXCROSSAL Values are presented as n (%). Target lesion failure was defined as a composite of cardiac death, target vessel MI, or ischemia-driven TLR. Patient-oriented composite endpoint was defined as a composite of all-cause death, all MI, or any revascularization. ID-TLR, ischemia-driven target lesion revascularization; MI, myocardial infarction; PoCE, patient-oriented composite endpoint; ST, stent thrombosis; TLF, target lesion failure; TLR, target lesion revascularization; TVMI, target vessel myocardial infarction; TVR, target vessel revascularization. Similar to previous studies,5,6 the results in this trial showed that the incidence of ST was 1.0%, and the incidence of very late ST was 0.6%, suggesting that EXCROSSAL has good long-term safety. The neointimal coverage of EXCROSSAL was 93.5% in 4 months and 98.6% in 12 months,7 which may be the reason that EXCROSSAL can reduce the occurrence of ST. While current studies, comparing BP-DES to DP-DES, have demonstrated no significant differences and overall comparable clinical outcomes, histopathological studies have shown that BP-coated stents can significantly reduce vascular wall inflammation and promote healing.8 Thus, the 5-year follow-up analysis confirmed low rates of ST and TLF in patients with EXCROSSAL implantation. For the high-risk factors of TLF, such as long lesion, small vessel, and multivessel diseases, the efficacy of EXCROSSAL still needs further evaluation in the larger-scale clinical application. Another publication ‘The safety and efficacy of Firesorb bioresorbable scaffold in first-in-man study for coronary artery disease: the four-year outcomes’ by Prof. Runlin Gao and colleagues from Beijing Fuwai Hospital investigated the 4-year clinical outcomes of patients following Firesorb bioresorbable scaffold (BRS) implantation.9 In this prospective, open-label, first-in-man study, patients with single de novo lesions in native coronary arteries were randomized 2:1 into two cohorts after successful Firesorb implantation: cohort 1 (n = 30) underwent multimodality imaging assessment at 6 and 24 months; and cohort 2 (n = 15) at 12 and 36 months. Overall, a total of 45 patients were enrolled and implanted with Firesorb BRS, including 35 males (77.8%) with average age (54.4 ± 9.3) years. At 4 years, 10 patients in cohort 1 were reexamined by coronary angiography and optical coherence tomography (OCT) examination. Among them, the stents of 2 patients were completely degraded and absorbed. Compared with the OCT images of the other 8 patients in cohort 2 at 3 years, the degree of stent degradation was increased, and no stent malapposition was found. In 4-year clinical follow-up, 2 patients suffered PoCE (4.4%): 1 patient underwent non-target vessel revascularization the day after index procedure and target vessel revascularization (non-target lesion revascularization) at 2-year imaging follow-up; the other patient underwent non ischemia-driven target lesion revascularization at 4-year angiographic follow up. There was no scaffold thrombosis or TLF events through 4 years (Table 2). The 4-year follow-up analysis of FIRESORB Values are presented as n (%). Target lesion failure was defined as a composite of cardiac death, target vessel MI, or ischemia-driven TLR. Patient-oriented composite endpoint was defined as a composite of all-cause death, all MI, or any revascularization. ID-TLR, ischemia-driven target lesion revascularization; ID-TVR, ischemia-driven target vessel revascularization; MI, myocardial infarction; PoCE, patient-oriented composite endpoint; ST, stent thrombosis; TLF, target lesion failure; TLR, target lesion revascularization; TVMI, target vessel myocardial infarction; TVR, target vessel revascularization. The 4-year follow-up analysis of FIRESORB Values are presented as n (%). Target lesion failure was defined as a composite of cardiac death, target vessel MI, or ischemia-driven TLR. Patient-oriented composite endpoint was defined as a composite of all-cause death, all MI, or any revascularization. ID-TLR, ischemia-driven target lesion revascularization; ID-TVR, ischemia-driven target vessel revascularization; MI, myocardial infarction; PoCE, patient-oriented composite endpoint; ST, stent thrombosis; TLF, target lesion failure; TLR, target lesion revascularization; TVMI, target vessel myocardial infarction; TVR, target vessel revascularization. Recently, large trials evaluating clinical results of BRS raised concerns about the safety and efficacy of these devices. Thinner struts and fast absorption characteristics could be a key to a solution of the relatively higher incidence of scaffold thrombosis.10 Firesorb BRS’s thickness is 100–125 μm with sirolimus using highly accurate and precise point spraying techniques. Meanwhile, a BRS-specific implantation strategy has been widely used. Therefore, implantation of the Firesorb BRS appeared preliminarily feasible and effective in the treatment of patients with noncomplex coronary lesions and would be a promising development to overcome the limitations.