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December 1, 2011 -- The first time that I heard about the issue of second and third generation drug-eluting stents becoming compressed or distorted was during a small interventional meeting this past summer. A cardiologist from Brazil showed slides of a few cases in which a PROMUS Element stent had been deformed due to catheter manipulation through the deployed stent. He thought it was important to point this out in case other physicians in the audience encountered this problem -- a problem which he easily solved by redilating the stent with a high pressure balloon. He did, however, note that, as a result of these occurrences, his cath lab was no longer using this particular stent. Since then similar cases have been published in EuroIntervention and the Journal of Interventional Cardiology; this phenomenon also was the subject of hastily-called seminars during the TCT 2011 meeting in November. It seems that this issue occurred predominantly with Boston Scientific's Element platform, but a case here and there involved an Endeavor, a Biomatrix or a Taxus stent.
Yesterday, Dr. John Ormiston, considered to be New Zealand's most experienced interventional cardiologist and co-principal investigator for Abbott's ABSORB first-in-man bioabsorbable stent trial, and his co-authors, Dr. Bruce Webber and Dr. Mark W. I. Webster, published their findings on this subject in JACC Cardiovascular Interventions, after extensive bench-testing of seven of the leading stent platforms. The result? Longitudinal compression had very much to do with the design of the stent -- and, of the new iteration of stents, Boston Scientific's Element/Omega design was the most susceptible (although it should be noted that the Element does score high in terms of flexibility and radial strength). Abbott's XIENCE V and XIENCE Prime platforms were the least susceptible with Medtronic's new Integrity platform very close behind. But Boston Scientific's Element showed 3-5 times the distortion. For more details, read our report about this study. Of course, for many of the interventional cardiologists I have informally polled about this issue, stent distortion is not that big a deal. It doesn't occur that frequently, especially when proper technique is employed, although Dr. Ormiston told me he thinks stent distortion is under-recognized and occurs more frequently than say, late stent thrombosis (although it is far less severe a complication since late stent thrombosis can be fatal). Additionally, stent distortion, if recognized, can be corrected. Speaking of "proper technique", as I learned waaaaaay back in the beginnings of balloon angioplasty, good technique means being very careful when crossing a treated area of the artery with a wire, a balloon, with anything. It's why interventionalists learn to treat the distal part of the artery first and work one's way back. It's kind of like not painting yourself into a corner: you don't want to walk over wet paint -- and you don't want to jiggle a catheter or guide wire through a recently placed stent. But sometimes you have to; sometimes you are in a situation, like an ostial lesion (one near the origin of the artery) where deep catheter engagement or manipulation is required. In such cases it is important to understand the issues involved. To whit, I hereby reprint Dr. Ormiston's thoughts, which he sent to me, about avoiding and repairing coronary stent distortion:
It should also be noted that Section 6.3 of the FDA-mandated Directions for Use (DFU) packaged with the PROMUS Element Plus Stent System is titled "Longitudinal Stent Deformation" and contains additional cautions regarding this issue. Reported by Burt Cohen, December 1, 2011 |
