More evidence has surfaced that the thinner design of next-generation coronary stents may be prone to crumpling after being deployed.
Dr. Cindy Grines, editor of the Journal of Interventional Cardiology, details a case in the journal’s October issue involving "marked shortening, deformation and accordion of the Ion coronary stent," something she hasn’t seen before in 25 years of practicing cardiology.
The stent involved in the case shortened by about 35 percent, Grines wrote.
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"We believe that accordion of the stent caused technical difficulties in rewiring the vessel and ultimately stent thrombosis, [and] thus is of serious concern. Although recent reports from Europe noted this phenomenon in the Element and Omega stents (similar family of stent designs), to my knowledge this is the first published case in the stent approved in the United States, the Ion stent," she wrote. "The Food and Drug Administration as well as Boston Scientific (NYSE:BSX) are aware of this issue and investigation is ongoing.
"Although this shortening phenomenon may just require an additional stent to ensure adequate coverage of the lesion, in our case it appeared that the stent may have deformed and involuted, further compromising the lumen and preventing additional device interventions," Grines wrote.
Evidence has been mounting that the thinner wire used to make next-gen stents might not be able to handle the pressure of percutaneous coronary interventions. An Irish study published earlier this month found that thinner stents may have lower longitudinal strength, potentially leading to stent thrombosis and a “catastrophic late complication” and leaving the target lesion unprotected, according to scientists at the Belfast Health & Social Care trust.
Citing data from a second bench test conducted by Abbott (NYSE:ABT) "showing that the Element family of stents (including the Omega and Ion) may shorten up to 46 percent under the force that an interventional cardiologist may exert to advance a post-dilation balloon or intravascular ultrasound device, Grines called the results "very disturbing."
"Hopefully, there will soon be new recommendations regarding the use of stents of this particular design for our community of interventional cardiologists. Until further data are available, our institution will use the Ion stent cautiously, and only when alternatives are unavailable for the size under consideration," wrote Grines, who is vice president of clinical and academic affairs at Detroit Medical Center’s Cardiovascular Institute and a professor at Wayne State University.
The Irish researchers looked at stents made by Boston Scientific and Abbott, as well as stents from Medtronic (NYSE:MDT), Johnson & Johnson (NYSE:JNJ) and Biosensors International Group. Their study compared Abbott’s Xience V’s and Xience Prime’s 81-micrometer thickness, for example, with J&J’s 140-micrometer Cypher and Cypher Select Plus.
If determined to be a flaw, the news could affect the $4 billion stent market, according to Bloomberg. That would leave Boston Scientific, which gets 20 percent of its revenues from drug-eluting stents, especially vulnerable, Wells Fargo Securities analyst Larry Biegelsen wrote in a note to investors. Abbott’s Xience stent features horizontal bars at connecting points that add to its longitudinal strength; Medtronic’s Integrity uses single-wire engineering to boost its strength, company representatives told the news service.
Stent shrinkage is relatively rare compared to other problems associated with clearing blocked vessels, BSX interim CEO Hank Kucheman told investors during the company’s third-quarter conference call.
“Stents have a lot of different properties, which vary from one to another,” noted New York Presbyterian Hospital and Colombia University Medical Center director of cardiovascular research Dr. Gregg Stone during a conference call discussing the Belfast report. “Some stents will be more prone to this complication than others. The question is to understand how frequent it is, when does it occur, how to prevent it and how to manage it.”
