A randomized, prospective, intercontinental evaluation of a bioresorbable polymer sirolimus-eluting coronary stent system: the CENTURY II (Clinical Evaluation of New Terumo Drug-Eluting Coronary Stent System in the Treatment of Patients with Coronary Artery Disease) trial

AIM

The aim of this study was to establish safety and efficacy of a new sirolimus-eluting stent with bioresorbable polymer, Ultimaster (BP-SES). Sirolimus-eluting stent with bioresorbable polymer was compared with everolimus-eluting, permanent polymer, Xience stent (PP-EES) in the frame of a CENTURY II clinical trial designed to make global clinical data compliant with regulatory requirements in Europe and Japan.

METHODS AND RESULTS

The CENTURY II is a prospective, multicentre, randomized (1 : 1), single blind, controlled, non-inferiority clinical trial conducted at 58 study sites in Japan, Europe, and Korea. A total of 1123 patients requiring a percutaneous coronary intervention (PCI) procedure, with implantation of drug-eluting stent (DES), were enrolled [total population (TP)]. Randomization of patients was stratified for the subset of patients matching requirements for DES in Japan (Cohort JR, n = 722). Baseline patient demographic and angiographic characteristics were similar in both study arms, with minimal differences between the TP and Cohort JR. The primary endpoint, freedom from target lesion failure (TLF) at 9 months-TLF [composite of cardiac death, target-vessel-related myocardial infarction (MI) and target lesion revascularization]-was 95.6% with BP-SES and 95.1% with PP-EES (Pnon-inferiority<0.0001). Composite of cardiac death and MI rate was 2.9 and 3.8% (P = 0.40) and target vessel revascularization was 4.5% with BP-SES and 4.2% with PP-EES (P = 0.77). The stent thrombosis rate was 0.9% in both arms. In Cohort JR, freedom from TLF was 95.9 and 94.6% (Pnon-inferiority < 0.0005) with BP-SES and PP-EES, respectively.

CONCLUSION

The new bioresorbable polymer sirolimus-eluting stent showed safety and efficacy profiles similar to durable polymer everolimus-eluting stent at 9-month follow-up.

STUDY REGISTRATION NUMBER

UMIN000006940.

An update on drug-eluting stents

OPINION STATEMENT

Coronary artery disease remains one of the major causes of morbidity and mortality worldwide. Percutaneous coronary intervention has been shown to be an effective treatment for angina pectoris, although it does not provide any prognostic benefit in stable patients. Drug-eluting stents (DES) have revolutionised the practice of interventional cardiology by permitting the percutaneous treatment of increasingly complex coronary artery lesions, which historically would have only been treated with surgery. There have been concerns with their long-term safety; however, the most recent large meta-analysis appears to suggest that these concerns are no longer a pertinent issue with the newest generation of stents. Consequently, DES are being used in complex patients and lesion types, and clinical data and guideline recommendations support this. New stent designs are also continually being developed, with the aim to further improve the safety profile of these devices. It must, however, be kept in mind that complacency following the impressive result from initial DES studies lead to, amongst others things, sub-optimal and careless stent deployment, and inappropriate patient selection, which may have ultimately contributed to the prior safety concerns. It is vital, therefore, that this is not repeated in light of the reassuring data, or with newer devices. Finally, as stent design improves, it is becoming increasingly difficult to identify meaningful and clinically relevant differences in stent performance without the requirement of a very large, expensive, randomised trial.

Myocardial bridging is a potential risk factor of very late stent thrombosis of drug eluting stent

Drug eluting stents have been implanted worldwide and used in nearly 90% of percutaneous coronary interventions in China. Although many randomized trials have confirmed the efficacy and safety profile of drug eluting stents, they were not powered to detect or exclude the effect of drug eluting stents on rare events such as stent thrombosis. Several mechanisms of very late stent thrombosis have been postulated, but are not widely accepted. Virchow’s triad describes the 3 main factors of thrombus formation – stasis of blood flow, endothelial injury and hypercoagulability. Myocardial bridging is a common congenital anomaly. Modern anatomy and angiography regard myocardial bridging as widespread, but its pathophysiological response is always ignored. According to Virchow’s triad, myocardial bridging negatively affect endothelial function, and the turbulent shear stress and intimal trauma predispose the vessel toward thrombus formation. Therefore, we question whether a relationship between myocardial bridging and very late stent thrombosis of drug eluting stents exists. Also, we propose that myocardial bridging might be a potential risk factor of very late stent thrombosis of drug eluting stents; coronary artery bypass grafting might be a promising and novel choice in the treatment of myocardial bridging with severe stenosis in the coronary artery.

Percutaneous treatment in acute coronary syndromes

Both ST-segment elevation myocardial infarction and non-ST-segment elevation acute coronary syndromes (ACS) are the result of an acute thrombotic lesion obstructing blood flow in the coronary vasculature. Percutaneous treatment has shown to improve clinical outcome in this clinical setting by resolving coronary obstruction with different devices directed to restore coronary blood flow. In comparison with balloon alone angioplasty, implantation of bare metal stents reduced the rate of restenosis and cardiac events, but high rates of restenosis remained, leading to further investigations to develop drug-eluting stents with different pharmacological coatings that reduced restenosis rates and clinical events. In this review, we discuss the current treatment of ACS, reviewing recent randomized clinical trials and advances in medical treatment, including new antiplatelet agents and recent guideline recommendations.