Elsevier

The Lancet

Volume 385, Issue 9962, 3–9 January 2015, Pages 43-54
The Lancet

Articles
A bioresorbable everolimus-eluting scaffold versus a metallic everolimus-eluting stent for ischaemic heart disease caused by de-novo native coronary artery lesions (ABSORB II): an interim 1-year analysis of clinical and procedural secondary outcomes from a randomised controlled trial

https://doi.org/10.1016/S0140-6736(14)61455-0Get rights and content

Summary

Background

Despite rapid dissemination of an everolimus-eluting bioresorbable scaffold for treatment for coronary artery disease, no data from comparisons with its metallic stent counterpart are available. In a randomised controlled trial we aimed to compare an everolimus-eluting bioresorbable scaffold with an everolimus-eluting metallic stent. Here we report secondary clinical and procedural outcomes after 1 year of follow-up.

Methods

In a single-blind, multicentre, randomised trial, we enrolled eligible patients aged 18–85 years with evidence of myocardial ischaemia and one or two de-novo native lesions in different epicardial vessels. We randomly assigned patients in a 2:1 ratio to receive treatment with an everolimus-eluting bioresorbable scaffold (Absorb, Abbott Vascular, Santa Clara, CA, USA) or treatment with an everolimus-eluting metallic stent (Xience, Abbott Vascular, Santa Clara, CA, USA). Randomisation was stratified by diabetes status and number of planned target lesions. The co-primary endpoints of this study are vasomotion (change in mean lumen diameter before and after nitrate administration at 3 years) and difference between minimum lumen diameter (after nitrate administration) after the index procedure and at 3 years. Secondary endpoints were procedural performance assessed by quantitative angiography and intravascular ultrasound; composite clinical endpoints based on death, myocardial infarction, and coronary revascularisation; device and procedural success; and angina status assessed by the Seattle Angina Questionnaire and exercise testing at 6 and 12 months. Cumulative angina rate based on adverse event reporting was analysed post hoc. This trial is registered at ClinicalTrials.gov, number NCT01425281.

Findings

Between Nov 28, 2011, and June 4, 2013, we enrolled 501 patients and randomly assigned them to the bioresorbable scaffold group (335 patients, 364 lesions) or the metallic stent group (166 patients, 182 lesions). Dilatation pressure and balloon diameter at the highest pressure during implantation or postdilatation were higher and larger in the metallic stent group, whereas the acute recoil post implantation was similar (0·19 mm for both, p=0·85). Acute lumen gain was lower for the bioresorbable scaffold by quantitative coronary angiography (1·15 mm vs 1·46 mm, p<0·0001) and quantitative intravascular ultrasound (2·85 mm2 vs 3·60 mm2, p<0·0001), resulting in a smaller lumen diameter or area post procedure. At 1 year, however, cumulative rates of first new or worsening angina from adverse event reporting were lower (72 patients [22%] in the bioresorbable scaffold group vs 50 [30%] in the metallic stent group, p=0·04), whereas performance during maximum exercise and angina status by SAQ were similar. The 1-year composite device orientated endpoint was similar between the bioresorbable scaffold and metallic stent groups (16 patients [5%] vs five patients [3%], p=0·35). Three patients in the bioresorbable scaffold group had definite or probable scaffold thromboses (one definite acute, one definite sub-acute, and one probable late), compared with no patients in the metallic stent group. There were 17 (5%) major cardiac adverse events in the bioresorbable scaffold group compared with five (3%) events in the metallic stent group, with the most common adverse events being myocardial infarction (15 cases [4%] vs two cases [1%], respectively) and clinically indicated target-lesion revascularisation (four cases [1%] vs three cases [2%], respectively).

Interpretation

The everolimus-eluting bioresorbable scaffold showed similar 1-year composite secondary clinical outcomes to the everolimus-eluting metallic stent.

Funding

Abbott Vascular.

Introduction

The implantation of a bioresorbable scaffold is a new approach that provides transient vessel support with drug delivery capability, potentially without the limitations of permanent metallic implants.1, 2 By liberating the coronary artery from the metallic caging, the vessel recovers pulsatility and becomes responsive to shear stress and physiological cyclic strain.3, 4, 5 The vessel wall, theoretically, can remodel and exhibit plaque reduction in response to pharmacological treatment and physiological stimuli. The potential of this technology has been shown in some studies with up to 3-year follow-up with several imaging modalities.6, 7, 8, 9, 10, 11

The use of bioresorbable scaffolds has several challenges that justify careful assessment of this technology. First, the mechanical property of the polymeric scaffold should match that of metallic stents; the acute recoil of the scaffold has previously been reported to be similar to that noted with an equivalent device in metal.12 The mechanical integrity and the absence of recoil has to be maintained for 6 months, during which time the biological process of restenosis (consisting of neointimal formation and constrictive remodelling) fully subsides, therefore not justifying a permanent prosthesis beyond this time.13 The second challenge to be taken into consideration is that the bioresorption of the polymeric scaffold should not trigger an inflammatory reaction that could result in late renarrowing of the vessel. Over time, the polymer is replaced by a provisional matrix made of proteoglycan that evolves into de-novo connective tissue.14 Eventual late enlargement of the scaffold and lumen has been documented at 2–3 years, compensating for the intraluminal growth of the neointima.15

In a randomised, single-blind, active-controlled trial (the ABSORB II study), we aimed to compare a bioresorbable everolimus-eluting scaffold with a metallic everolimus-eluting stent to treat ischaemic heart disease. Because the bioresorbable scaffold has been commercially available since August, 2012, and has been widely and rapidly disseminated in the absence of comparative data from randomised trials, the steering committee and trial funder decided to report secondary clinical and procedural endpoints at 1 year. Hence, we report secondary endpoints for clinical, procedural, anginal, and disease-related quality-of-life outcomes.

Section snippets

Study design and participants

The ABSORB II trial is a prospective, randomised, active-controlled, single-blind, parallel two-group, multicentre clinical trial. Eligible participants were aged 18–85 years with evidence of myocardial ischaemia, were suitable for coronary artery bypass graft surgery, and had one or two de-novo native lesions in different epicardial vessels. Patients with acute myocardial infarction before the procedure without normalised cardiac enzymes, evidence of ongoing acute myocardial infarction before

Results

Between Nov 28, 2011, and June 4, 2013, we enrolled 501 patients from 46 sites in Europe and New Zealand, and randomly assigned them to the bioresorbable scaffold group (335 patients) or the metallic stent group (166 patients; figure 1).

Table 1 shows patient demographics, risk factors, and use of antianginal drugs and antiplatelet therapy at baseline. The prevalence of diabetes was 24%, with more than a quarter of these patients being insulin dependent. Roughly 20% of patients presented with

Discussion

The main findings of this interim report of secondary outcomes and post-hoc analysis of 1-year follow-up data are that the device success rate of the bioresorbable scaffold matched that of the metallic stent; acute recoil of both devices were similar; the procedural lumen gain was slightly less with the bioresorbable scaffold than with the metallic stent because of the use of smaller balloons at lower pressure for deployment and dilatation of the bioresorbable scaffold; and that functional

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