Lancet: Bioabsorbable stents perform well in multi-center trial

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The implantation of a bioabsorbable everolimus-eluting stent produces an acceptable in-stent late loss, minimal intrastent neointimal hyperplasia and a low stent area obstruction, according to a study the March 15 issue of The Lancet.

The bioasorbable everolimus-eluting stent (BVS), developed by the Santa Clara, Calif.-based Abbott Vascular, 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.

John A Ormiston, MD, of the Auckland City Hospital in Auckland, New Zealand, and colleagues, assessed the feasibility and safety of this BVS stent. Ormiston declared that he has no conflict of interest, and is not an employee of Abbott.

In this prospective, open-label study, the researchers enrolled 30 patients, aged 18 years or older, who had either stable, unstable or silent ischemia and a single de-novo lesion that was suitable for treatment with a single 3x12 mm or 3x18 mm stent.

The investigators enrolled in the ABSORB study patients in four academic hospitals: Auckland City Hospital; Thoraxcenter, Erasmus Medical Center in Rotterdam, The Netherlands; Jagiellonian University in Krakow, Poland; and Aarhus University Hospital in Skejby, Denmark.

The composite endpoint was cardiac death, MI and ischemia-driven target lesion revascularization (TLR), which were available for 26 patients and intravascular-ultrasound endpoints for 24 patients, according to the authors.

Ormiston and colleagues reported that the clinical endpoints were assessed in all 30 patients at six and 12 months. In a subset of 13 patients, optical coherence tomography was undertaken at baseline and follow-up.
In the study, the reference-vessel diameter of the target lesion was 3 mm and the stenosis diameter 50 percent or more and less than 100 percent, with a thrombolysis in MI flow grade of more than one, the investigators reported.

The researchers also reported that when additional stenting was required, the Cypher sirolimus-eluting stent, developed by Johnson & Johnson’s Cordis of Miami, Fla., was used, because there were no animal or preclinical data for overlapping BVS stents.

For medical therapy, the investigators said that all patients were required to receive more than 75 mg of aspirin daily for the study duration (five years) and 75 mg of clopidogrel daily for a minimum of six months.

Ormiston and colleagues reported that the procedural success was 100 percent (30/30 patients), and device success 94 percent (29/31 attempts at implantation of the stent). At one year, the investigators said that the rate of major adverse cardiac events was 3.3 percent, with only one patient having a non-Q wave MI and no TLRs.

The researchers did not record any events of late stent thromboses. At the six-month follow-up, Ormiston and colleagues found that the angiographic in-stent late loss was 0.44 mm, which they said was mainly due to a mild reduction of the stent area as measured by intravascular ultrasound. The neointimal area was small (0.30 mm_), with a minimal area obstruction of 5.5 percent, the authors wrote.

Based on these findings, the researchers said that “the BVS stent has shown excellent clinical safety up to one year after the index procedure.”

The researchers said the study is not randomized because it is designed to provide preliminary observations and generate hypotheses for future studies. They also noted that the follow-up duration (one year) might be too short to capture all events, and said they will undertake further invasive follow-up at two years and clinical follow-up to five years.

Abbott funded the study.