A bioabsorbable everolimus-eluting coronary stent system for patients with single de-novo coronary artery lesions (ABSORB): a prospective open-label trial

Summary

Background

A fully bioabsorbable drug-eluting coronary stent that scaffolds the vessel wall when needed and then disappears once the acute recoil and constrictive remodelling processes have subsided has theoretical advantages. The bioasorbable everolimus-eluting stent (BVS) has a backbone of poly-L-lactic acid that provides the support and a coating of poly-D,L-lactic acid that contains and controls the release of the antiproliferative agent everolimus. We assessed the feasibility and safety of this BVS stent.

Methods

In this prospective, open-label study we enrolled 30 patients who had either stable, unstable, or silent ischaemia and a single de-novo lesion that was suitable for treatment with a single 3·0×12 mm or 3·0×18 mm stent. Patients were enrolled from four academic hospitals in Auckland, Rotterdam, Krakow, and Skejby. The composite endpoint was cardiac death, myocardial infarction, and ischaemia-driven target lesion revascularisation. Angiographic endpoints were available for 26 patients and intravascular-ultrasound endpoints for 24 patients. Clinical endpoints were assessed in all 30 patients at 6 and 12 months. In a subset of 13 patients, optical coherence tomography was undertaken at baseline and follow-up. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00300131.

Findings

Procedural success was 100% (30/30 patients), and device success 94% (29/31 attempts at implantation of the stent). At 1 year, the rate of major adverse cardiac events was 3·3%, with only one patient having a non-Q wave myocardial infarction and no target lesion revascularisations. No late stent thromboses were recorded. At 6-month follow-up, the angiographic in-stent late loss was 0·44 (0·35) mm and was mainly due to a mild reduction of the stent area (−11·8%) as measured by intravascular ultrasound. The neointimal area was small (0·30 [SD 0·44] mm²), with a minimal area obstruction of 5·5%.

Interpretation

This study shows the feasibility of implantation of the bioabsorbable everolimus-eluting stent, with an acceptable in-stent late loss, minimal intrastent neointimal hyperplasia, and a low stent area obstruction.

Funding

Abbott Vascular.

Introduction

Conventional stents restrict restenosis after percutaneous coronary intervention by scaffolding intimal flaps that have separated from deeper arterial layers, by control of early elastic recoil, and prevention of the subsequent constrictive remodelling that were major limitations of balloon angioplasty.1, 2 The neointimal growth response to stenting that contributes to restenosis can be largely abolished by coating stents with antiproliferative drugs. However, there is a low incidence of late stent thrombosis, which is probably because the antiproliferative drugs delay the growth of healthy endothelium over stent struts and their durable polymer coating.3, 4, 5 The need for vessel scaffolding and drug delivery is temporary, and permanent scaffolding is superfluous after the vessel has healed. A bioabsorbable stent might have less potential for late stent thrombosis because there will eventually be no foreign material exposed to blood if endothelialisation is delayed or incomplete.3, 4 Furthermore, permanent metallic stenting can preclude surgical revascularisation, jail side branches, prevent expansive remodelling, eliminate reactive vasomotion, and impair non-invasive imaging of coronary arteries with multislice CT and MRI.

Tamai and colleagues⁶ examined the safety and feasibility of the bioabsorbable but non-drug-eluting poly-L-lactic acid (PLLA) Igaki-Tamai stent (IgakiMedical, Kyoto, Japan) in a prospective unblinded clinical investigation of 50 patients. The rate of major adverse cardiac events was 14% at 12 months, 16% at 36 months, and 18% at 48 months. These results are similar to those after metallic non-drug-eluting stent implantation, reporting the feasibility and safety of a bioabsorbable PLLA polymer stent.² Erbel and co-workers⁷ have described the outcome of a metallic biocorrodable stent. However, the neointimal hyperplasia and the recoil that was recorded with this stent resulted in a high restenosis rate, precluding further clinical use.⁷ Bioabsorbable polymer drug-eluting stents are an alternative approach, providing short-term vessel scaffolding combined with drug delivery capability but avoiding the long-term restrictions of metallic stents.

The bioasorbable everolimus-eluting stent system (BVS; Abbott Vascular, Santa Clara, CA, USA) is made from a bioabsorbable polylactic acid backbone which is coated with a more rapidly absorbed polylactic acid layer that contains and controls the release of the antiproliferative drug, everolimus (Novartis, Basel, Switzerland). The ABSORB study aimed to assess the feasibility and safety of the BVS stent in patients with single de-novo coronary artery lesions.