The Promise of Biabsorbable Stents

By Annie Ruppert, RN, BSN

Well, this is what we have all been waiting for, isn’t it? We have been using drug-eluting stents (DES) for some time now and have patiently been waiting for new developments and improvements in the world of stents.

Issues that biodegradable stents address include the need for long-term dual anti-platelet therapy and help for those multiple stent procedure patients who now have what cath lab staff usually refer to as a “full medical jacket.” Unfortunately, if these patients need bypass surgery, it is almost impossible to do, because there are so many stents in the artery. If, however, these stents were absorbable and disappeared over time, these patients could indeed be treated with a bypass operation.

One very exciting hypothesis regarding absorbable stents is the possibility that the artery could actually improve once the metal material was gone. Healthy arteries are able to handle pulsatile force and shear stress, while arteries that have stents in place are not able to do so. Dr. Robert Schwartz explained that “bioabsorbable stents might also safely and reliably transform the histology, the cellular architecture, of the artery. Early data suggest it might be possible to transform an atherosclerotic artery into a relatively healthy one.” (1) If this indeed turns out to be the case, bioabsorbable stents could be used as a preventative therapy.

Many issues regarding bioabsorbable stents are controversial, but it does seem that research is moving in a positive direction. There have been some trials with biodegradable stents and some data is now available. Of course, the trials did not include complex, calcified, or bifurcation lesions, so it remains to be seen how well these stents will work in these situations. The main difficulties seem to be developing a bioabsorbable stent that is easy to deliver, has a low profile, and is reabsorbed within a time frame that will give you the best benefit. “Early studies with bioabsorbable stents tested in the PROGRESS-AMS trial showed loss of radial strength which resulted in high rates of restenosis which was felt to be caused by the stent being too quickly absorbed.”(2) Dr. Raoul Bonan (Montreal Heart Institute, QC) comments that “the new technology needs to balance absorption and inflammation, and that absorption needs to be slow enough to prevent increased inflammation.”(1)

More trials need to be performed, without question. How exciting is it, though, to be living in an age where technological developments with stents may get to a point where stents can be used before a patient develops a severe stenosis and symptoms? In the ABSORB trial (primary investigator Professor Patrick Serruys), results have shown in some cases that “there is actual plaque regression in the earliest first-in-human data.”(2)

References
1. Now you see me, now you don’t: The bioabsorbable stent in clinical practice: November 8, 2010; Michael O’Riordan: Heartwire: theheart.org. Available online at http://www.theheart.org/article/1144463.do [1]. Accessed January 6, 2011.

2. Updates on bioabsorbable stents: ABSORB and PROGRESS-AMS trials. Theheart.org. (Interventional/Surgery; May 31, 2007). Available at http://www.theheart.org/article/794029.do [2]. Accessed January 6, 2011.

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