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@NEJM Ask the Authors & Experts: Everolimus-eluting Bioresorbable Scaffolds for Coronary Artery Disease & Bioresorbable Vascular Scaffolds--Will Promise Become Reality?

Original Article

Everolimus-Eluting Bioresorbable Scaffolds for Coronary Artery Disease


In patients with coronary artery disease who receive metallic drug-eluting coronary stents, adverse events such as late target-lesion failure may be related in part to the persistent presence of the metallic stent frame in the coronary-vessel wall. Bioresorbable vascular scaffolds have been developed to attempt to improve long-term outcomes.


In this large, multicenter, randomized trial, 2008 patients with stable or unstable angina were randomly assigned in a 2:1 ratio to receive an everolimus-eluting bioresorbable vascular (Absorb) scaffold (1322 patients) or an everolimus-eluting cobalt–chromium (Xience) stent (686 patients). The primary end point, which was tested for both noninferiority (margin, 4.5 percentage points for the risk difference) and superiority, was target-lesion failure (cardiac death, target-vessel myocardial infarction, or ischemia-driven target-lesion revascularization) at 1 year.


Target-lesion failure at 1 year occurred in 7.8% of patients in the Absorb group and in 6.1% of patients in the Xience group (difference, 1.7 percentage points; 95% confidence interval, −0.5 to 3.9; P=0.007 for noninferiority and P=0.16 for superiority). There was no significant difference between the Absorb group and the Xience group in rates of cardiac death (0.6% and 0.1%, respectively; P=0.29), target-vessel myocardial infarction (6.0% and 4.6%, respectively; P=0.18), or ischemia-driven target-lesion revascularization (3.0% and 2.5%, respectively; P=0.50). Device thrombosis within 1 year occurred in 1.5% of patients in the Absorb group and in 0.7% of patients in the Xience group (P=0.13).


In this large-scale, randomized trial, treatment of noncomplex obstructive coronary artery disease with an everolimus-eluting bioresorbable vascular scaffold, as compared with an everolimus-eluting cobalt–chromium stent, was within the prespecified margin for noninferiority with respect to target-lesion failure at 1 year. (Funded by Abbott Vascular; ABSORB III ClinicalTrials.gov number, NCT01751906.)


Bioresorbable Vascular Scaffolds — Will Promise Become Reality?


All other things being equal, most of us would agree that a coronary-artery stent that disappears after its useful function has been served would be preferable to a permanently indwelling device. Late stent failure occurs at a low but steady rate with the passage of time,1 and an increasing body of evidence implicates an accelerated form of atherosclerosis inside the stent as a common underlying cause.2 Moreover, the presence of a rigid metal scaffold in the vessel wall permanently abolishes physiologic vasomotion in the stented area.

With this in mind, researchers have sought to develop self-degrading coronary stents with enough strength to produce a good short-term result and a degradation profile that results in gradual breakdown in a safe manner.3 Thus far, most success in the field has been with polylactic acid stent technology. Two such devices have received CE-mark approval, which is a prerequisite for clinical use in Europe: the everolimus-eluting Absorb bioresorbable vascular scaffold system (Abbott Vascular) in 2011 and the novolimus-eluting DESolve bioresorbable coronary scaffold system (Elixir Medical) in 2013.