Dedicated Bifurcation Stent Looks Promising at Nine Months

Shelley Wood

January 20, 2009

January 20, 2009 (Washington, DC) — A new, self-expanding, drug-eluting stent with a flared configuration has proved itself to be safe and effective in bifurcated lesions, at least out to nine months, in the Drug-Eluting Stent Intervention for Treating Side Branches Effectively (DIVERGE) study [1]. Results from the nonrandomized study were reported by Dr Stefan Verheye and colleagues online January 14, 2009 in the Journal of the American College of Cardiology.

The Axxess stent (Devax, Lake Forest, CA) is one of a new breed of bifurcation stents intended for deployment at the level of the carina, thereby allowing easier access to the distal parent vessel and side branch, each of which can also be treated, if warranted, by PCI and provisional stenting. According to the DIVERGE study authors, the design of the stent, as well as the technical approach, is geared toward providing maximum drug coverage yet minimum stent overlap. The stent itself is made of superelastic (austenitic) nitinol and elutes biolimus A9, an antiproliferative drug derived from sirolimus, from a bioabsorbable polymer.

Access to Bifurcation Branches

For their multicenter study, Verheye et al treated 302 patients with de novo bifurcation lesions with a total of 299 Axxess stents (the stent could not be used for anatomic reasons in three patients), followed by additional sirolimus-stenting of the parent and/or side branch as needed. In all, 21.7% of patients received an additional stent in one branch, and 64.7% had stenting of both branches. At nine months, the MACE rate was 7.7%, subacute and late stent-thrombosis rates were relatively low, and angiographic restenosis (defined as restenosis >50%) was 6.4%. Analyzed on a per-branch basis, restenosis rates were 3.6% for the parent vessel and 4.3% for the side branch, while late loss was 0.20 mm for the parent vessel and 0.17 mm in the side branch. For the area covered by the Axxess stent, percent neointimal volume obstruction, measured by intravascular ultrasound (IVUS), was 4.3%.

Dr John Ormiston (Auckland City Hospital, New Zealand), one of the investigators for DIVERGE, told heartwire that he thinks the Axxess stent would be a good option to have on the cath-lab shelf.

"Having worked with many dedicated bifurcation devices clinically and on the bench, I am very impressed with the Axxess stent; I like the device," he said. "Using it, I feel in control and know that I can achieve excellent initial and long-term angiographic and clinical results. I think it is easy to use once the difference in technique required for a self-expanding stent is understood."

A variety of different methods, including the culotte, crush, and T-stenting techniques have evolved for the treatment of bifurcation lesions, picking up pace in the drug-eluting-stent era, but recent trials have suggested that the T-stenting technique, whereby the main branch is stented and a "provisional" second stent is placed only if deemed absolutely necessary, may be the better option than starting off with the intention of stenting both branches.

"A major advantage for an operator using the Axxess stent in contrast to a conventional provisional side-branch stenting strategy is the security of knowing that the side branch is easily accessed with Axxess for additional stenting if necessary," Ormiston explained. "When bifurcations with large side branches are treated with a conventional provisional technique, there is always the concern that it may not be possible to access the side branch for additional stenting. The consequences of occlusion of a small side branch may be small, but this is not true if a large side branch becomes occluded."

Ormiston conceded to heartwire that nine-month clinical results are not enough to be fully confident in the safety and long-term efficacy of the device. While stent-thrombosis rates were low in DIVERGE, bifurcation lesions are associated with a higher risk of thrombosis generally. "We do not know what the very late thrombosis rate will be, but this risk needs to be balanced against the risks posed by bifurcation disease," he noted.

He also called for a trial comparing provisional stenting techniques and the Axxess stent. "It may be that outcomes in high-risk bifurcations using the Axxess stent would be better than those after provisional side-branch stenting techniques, and I think an adequately powered randomized trial should be done."

Verheye lists no financial conflicts of interest in the paper. Ormiston notes being on the advisory board for Devax, Abbott Vascular, and Boston Scientific.

  1. Verheye S, Agostoni P, Dubois CL, et al. Nine-month clinical, angiographic, and intravascular ultrasound results of a prospective evaluation of the Axxess self-expanding biolimus A9-eluting stent in coronary bifurcation lesions. The DIVERGE (Drug-Eluting Stent Intervention for Treating Side Branches Effectively) study. J Am Coll Cardiol 2008; DOI:10.1016/j.jacc.2008.12.012. Available at: http://content.onlinejacc.org.



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