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Bioresorbable scaffolds increase risk for thrombotic events vs. drug-eluting stents
At mid- and long-term follow-up, the risks for scaffold thrombosis and other thrombotic events were elevated in adults who received bioresorbable vascular scaffolds compared with everolimus-eluting metallic stents, according to findings published in Annals of Internal Medicine.
“Drug-eluting stents reduce the rate of in-stent restenosis, myocardial infarction and target lesion revascularization (TLR) compared with bare-metal stents for adults undergoing percutaneous coronary interventions, but concerns remain about the risk for late and very late stent thrombosis with drug-eluting stents,” Xin-Ling Zhang, MD, from the Nanjing University School of Medicine, China, and colleagues wrote. “Bioresorbable vascular scaffolds (BVSs) were designed to reduce the late thrombotic events associated with metallic stents. Early, modest-sized studies showed similar midterm cardiovascular safety with everolimus-eluting metallic stents (EESs) and BVSs, but meta-analyses published in 2016 suggested a possible increased midterm risk for scaffold or stent thrombosis and myocardial infarction with BVSs.”
Zhang and colleagues performed a systematic review and meta-analysis to determine how often scaffold thrombosis occurred after BVS implantation and compared the safety and efficacy of everolimus-eluting BVSs with EESs at mid- and long-term follow-up in patients who underwent percutaneous coronary intervention. The researchers searched several databases and identified seven randomized trials and 38 observational studies that followed patients with coronary artery disease who had a BVS or an EES and experienced scaffold or stent thrombosis, death, MI or revascularization for at least 6 months.
After BVS implantation, the pooled incidence of definite or probable scaffold thrombosis was 1.8% (95% CI, 1.5%-2.2%; 41 studies; n = 21,884) at a median follow-up of 1 year and 0.8% (95% CI, 0.5%-1.3%; 14 studies; n = 4,688) at a median follow-up beyond 1 year, according to results.
BVSs were associated with a more than threefold increased risk for definite or probable scaffold thrombosis (OR = 3.40; 95% CI, 2.01-5.76) at a median follow-up of 25 months compared with EESs (7 trials; n = 5,578). This risk was greater at early (within 30 days), late (1 month to 1 year) and very late (beyond 1 year) thrombosis, with the odds of definite or probable scaffold or stent thrombosis almost doubling after 1 year (OR = 4.81; 95% CI, 1.82-12.67) compared with incidences within 1 year (OR = 2.59; 95% CI, 1.44-4.66).
BVSs were associated with elevated risks for MI (OR = 1.63; 95% CI, 1.26-2.10), target lesion revascularization (OR = 1.31; 95% CI, 1.03-1.67) and target lesion failure (OR = 1.37; 95% CI, 1.12-1.66), which increased over time. There was no difference between groups in incidences of all-cause, cardiac and noncardiac death, target vessel revascularization and any revascularization.
“Compared with EESs, BVSs were associated with consistently increased risks for scaffold or stent thrombosis and other thrombotic events at mid- and long-term follow-up,” Zhang and colleagues concluded. “All these observed increased risks increased further over time. Optimal scaffold-specific techniques and better-designed scaffolds are needed to improve the clinical outcomes of BVSs.”
In a related editorial, Sanket S. Dhruva, MD, and Jeptha P. Curtis, MD, both from Yale University School of Medicine, New Haven, Conn., and colleagues wrote that the findings by Zhang and colleagues show a role for a robust device surveillance program to assess new devices.
“The goal of providing patients with access to beneficial new technologies means that long-term follow-up will not always be available at approval, but such data must be obtained, monitored and acted on rapidly to ensure that patients are receiving safe and effective devices,” they wrote. “The creation of the National Evaluation System for Health Technology is an important step toward meeting this need, but its success will require stakeholders to set aside self-interest for the greater good of public safety.” – by Alaina Tedesco
Disclosures: Curtis reports receiving grants from the National Heart, Lung, and Blood Institute and salary support from the American College of Cardiology and CMS, and holding equity interest in Medtronic. The other authors report no relevant financial disclosures.
Perspective
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This study expands on what has previously been reported in clinical trials, registries, as well as prior meta-analyses and suggests that the risk of device-oriented adverse events, particularly definite or probable stent thrombosis, is increased with the everolimus-eluting bioresorbable scaffolds as compared with the permanent everolimus-eluting metallic stents. This study represents a larger meta-analysis, which summarizes data from 7 randomized trials and 38 observational studies, with a median follow-up of 12 months (range 6-36 months) and indicates that bioresorbable stents are associated with an increased risk of scaffold thrombosis as well as an increased risk of myocardial infarction, target lesion revascularization and target lesion failure, with risks increasing over time.
Given the data from clinical trials, observational studies, meta-analyses and the recent FDA safety warning to providers of a higher rate of cardiac events in patients receiving the Absorb (Abbott) stent, the bioresorbable scaffolds have taken a backseat in the United States. In contemporary clinical practice, the latest generation of drug-eluting permanent scaffolds is considered to be the “gold standard” therapy for percutaneous treatment of obstructive coronary artery disease, with proven short- and long-term efficacy and safety data. Bioresorbable stents should be avoided in small vessels and careful attention should be paid to the BVS implantation technique (i.e. predilation, scaffold sizing, postdilation, intravascular imaging). I believe that bioresorbable scaffold technology is promising, and though the first generation may not yet be ready for prime time due to its inferior safety profile with respect to scaffold stent thrombosis, the next generation bioresorbable stents with thinner struts and faster scaffold resorption, may overcome the shortcomings of the first generation BVS.