May 24th, 2011

Stent BioWars: Erode or Absorb?


In January 2011, we blogged about ABSORB, a  bioresorbable stent, when it received CE approval for use in Europe.

Drug-eluting stents (DES) are composed of a metal scaffold that is coated with a polymer containing an antiproliferative agent , which is released gradually over the weeks to months after the stent is inserted.  The durable polymer residue has been implicated as a cause of persistent arterial wall inflammation and delayed vascular healing, which may play a role in the occurrence of late stent thrombosis and restenosis (>12 months after PCI).  If so, stent polymers that erode after drug release may potentially reduce late complications.

At the EuroPCR 2011 meeting, researchers presented findings of a meta-analysis of  3 studies (ISAR-TEST-3, ISAR-TEST-4, and LEADERS, each with 3 years of follow-up) of DES with either bioerodable polymers or durable polymers (i.e., Cypher). Compared with durable polymers, bioerodables were associated with less stent thrombosis (1.2% vs. 2.1%; P=0.013) and better outcomes (incidence of cardiac death, MI, and target lesion revascularization, 18.2% vs. 21.1%; P=0.04).

Late stent thrombosis and restenosis are uncommon occurrences; however, this meta-analysis provided sufficient patient numbers (2358 patients with bioerodable-polymer stents and 1704 patients with Cypher stents) to detect a statistically significant difference in outcomes.

If the incidence of late complications after DES implantation is reduced by making the polymer disappear, do you think that making the entire stent disappear will be a significant improvement?

5 Responses to “Stent BioWars: Erode or Absorb?”

  1. Fahim H Jafary, MD, FACC, FSCAI says:

    Not sure. On the one hand it’s clearly extremely attractive to have the stent disappear and vascular physiology be completely restored at the treated site. However, I don’t know what would happen at the site long term (years down the line) as the stent dissapates – will it re-narrow? Will it form aneurysms? We won’t know until quite some time down the line. The global experience with bare stents, on the other hand, spans close to 20 years and the safety track record is excellent. Hence a DES that morphs into a truely bare stent is more reassuring and attractive to me.

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  2. I agree with you. But one thing attractive about a resorbable stent is that it may not preclude a bypass graft being placed at that site later on. We’ve all seen “full metal” coronaries that prevented CT surgeons from placing bypass grafts.

  3. miroslav vytiska, MD says:

    ST and ISR after DES are complications with many potencial contributing factors – from patient´s compliance to procedural result and design of stent may be also important.
    According our experiences most common causes of ST are incompliance to DAT and suboptimal result of PCI. For ISR is crucial procedural result – optimal stent aposition, no edge dissection, optimal size of stent, size and site of the vessel- small versus large diameter, bifurcation lenght of the lesion, ect….
    I thing that design of stent and its disappearing are of secondary importance in rate of ISR or ST and impact of bioresorbalbe stents on these complication will not be significant.
    In respect of CABG – there is no difference – when the stent is occluded and bypass in needed distal anastomosis must be placed behind the occlusion, ragadless the stent is resorbed or perzistent in vessel wall.

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  4. Fahim H Jafary, MD, FACC, FSCAI says:

    Dr. Lange
    You are right about those specific cases – indeed an absorbable stent would carry a potential advantage in them. That said, such patients are, in the big picture, quite uncommon (even though they stick in our minds) and most patients won’t have stents placed all the way into the distal LAD, for example, unless either the patient wasn’t a surgical candidate to begin with or the interventionalist was faced with a dissection all the way down (or just loved to stent period!). If I may dare to mention it, POBA with drug-eluting balloons may be a better option in distal disease particularly small vessels.

    In principle, the concept of the absorbable stent is fantastic and I’m not belittling it for one minute. For some reason the vasculature doesn’t always behave the way it should and we will need to be cautiously optimistic regarding the long-term outlook once the stent disappears. On the other hand several bioabsorbable polymer stents are already out there (Nobori from Terumo, Biomatrix from Biosensor) and polymer-less stents are in the making (Nevo from Cordis is one that comes to mind) where the DES becomes a BMS in a year. What would be even better is if the process can be shortened to a few months.

  5. Bioabsorbable stents (when i heard few months back), i almost jumped out of my chair that, are ST & ISR not enough of complications? that we are ready to remove the scaffolding too, when one of my senior’s asked me ” how many times have you heard of arterial wall collapse leading to ischemia”. NEVER. so the idea – the results – continued efforts for reducing DES to BMS time to few months, all looks great – but what about affordability , Cost benefit analysis ?

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