Boston Scientific (NYSE:BSX) sought to dispel concerns that its thinner next-generation stents may be more prone to crumpling than some other models with the release of results from 2 randomized clinical trials which found no instances of deformation with the med-tech titan’s newest stents.
In a study of more than 2,400 patients implanted with stents from the Element, Promus or Taxus Express platinum-chromium platforms, researchers found no cases of stent shortening or lengthening in the Perseus and Platinum trials, according to a press release.
Stent deformation gained a lot of attention in December 2011 when researchers bench-tested 7 different stents from various manufacturers, concluding that some devices made by Boston Scientific and Medtronic (NYSE:MDT) fared worse than competing designs.
Boston Scientific’s Promus Element stent, which landed FDA clearance days before the crumpling study was released, was the 3rd-weakest tested, according to the study.
The company became a lightning rod for crumpling concerns after at least 2 studies and a case study presented at the Transcatheter Cardiovascular Therapies conference in San Francisco in November 2011 detailed incidents in which either a BSX Ion or Promus stent deformed after deployment.
The FDA soon took an interest, launching an investigation into the newer stent models. The federal watchdog agency found that, although there’s been only 1 reported incident of deformation involving a Promus stent from more than 4,600 implantations in clinical trials, "an unspecified number of significant adverse events had been reported."
The FDA ultimately required that Boston Scientific include a warning on the potential for stent "shrinkage" in the labeling for the Promus Element drug-eluting stent.
The device maker went on the offensive against crumpling concerns in January with a new video, "Beyond the hype: A closer look at the manifestation and clinical impact," stressing that longitudinal stent deformation is a rarity that can occur with any of the newer stent platforms, including its own platinum-chromium line and competing devices from Abbott (NYSE:ABT) and Medtronic.
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 3rd-quarter conference call.
"In this large, systematic, angiographic analysis by an independent core laboratory, the data suggest that previously reported cases of longitudinal stent deformation are a rare occurrence among the stent platforms studied and across the spectrum of target lesion complexity evaluated," Dr. Dean Kereiakes, who presented the new study results at the American College of Cardiology conference in Chicago this week, said in prepared remarks. "This analysis and methodology may provide useful insights for future studies evaluating the incidence and clinical implications of longitudinal stent deformation."
The Perseus and Platinum trials represent the largest systematic, independent core lab analysis to assess the stent deformation risk across multiple drug-eluting stent platforms, according to the release.
"Longitudinal stent deformation has been shown to be a rare event that can occur with many coronary stents, regardless of manufacturer, strut thickness, number of connectors or alloy composition," BSX’s global chief medical officer Dr. Keith Dawkins added in prepared remarks. "The excellent radiopacity of the platinum chromium stent series can help physicians identify and treat longitudinal stent deformation in the rare cases when it does occur, as well as facilitate accurate stent placement and complete stent expansion during all implantations."
Boston Scientific can notch that as a win for its Pt-Cr alloys, following last week’s study results finding that rates of stent thrombosis were "significantly lower" with cobalt-chromium everolimus-eluting stents like Abbott’s Xience V, which it licenses to Boston Scientific as the Promus stent. The study also found that all drug-eluting stents tested proved safer and more effective than their bare-metal forebears in the largest meta-analysis to date.
Boston Scientific plans this year to phase out the Promus stents in favor of the next-generation Promus Element platinum-chromium designs, according to the company’s annual report. The private-label deal ended in Europe in 2009, but a similar arrangement in the U.S. is slated to go until mid-2012.
Boston Scientific won FDA clearance for its Promus Element DES in November 2011 and launched the system in the 4th quarter. The company launched the Promus Element in Japan earlier this month.
"We are pleased that this analysis reaffirms the safety profile of our Promus and Promus Element everolimus-eluting stents, which use the same drug and polymer combination and drug-release characteristics of the cobalt chromium stents analyzed in this publication," a Boston Scientific spokesman told MassDevice in an email. "In particular, we were pleased to see that in this analysis the platinum chromium Promus Element stent also demonstrated lower stent thrombosis rates compared to bare-metal or zotorolimus-eluting stents."