An example of a drug-eluting stent expanded by a balloon catheter. Image is of a Boston Scientific Promus Premier stent.
(Editor's note: this article was updated in March 2017 with links at the bottom to more current stent technology articles from 2016 and 2017)
There are great comeback stories throughout sports history. One of the more recent ones was when Bo Jackson, who played NFL football and MLB baseball, had hip-replacement surgery, yet came back to play two more years of professional baseball on an artificial hip. This feat was recognized when Jackson won the Major League Baseball Comeback Player of the Year Award in 1993.
Much more rare are comebacks in healthcare technology, but we may be witnessing one such return today with drug-eluting stents (DES). After a pullback in the DES market and a reemergence of the use of bare metal stents (BMS) due to concerns of DES-related thrombosis, the DES market is starting to rebound, reports Millennium Research Group.
The new optimism is good news for new drug-eluting stent platforms released at the start of 2008, and others awaiting the FDA go-ahead. For the clinician, that means more information to learn and assimilate, while weighing which platform is the optimal selection in a particular patient.
In 2006, DES use reached 90 percent of the total stent market. From 2006-2007 there was a 35 percent decline in total DES use. The total coronary stent market declined by just under 30 percent and there was a resurgence in BMS use.
Over the last couple of years, emerging reports concerning late stent thrombosis have caused a pullback in the DES market and a reemergence of the use of BMS. An FDA-panel finding in December 2006, found that DES are as safe as BMS when used in accordance with the product label, but endorsed prior recommendations of the AHA/ACC/SCAI to increase the duration of dual antiplatelet therapy (DAPT) for both approved DES to one year for patients who can tolerate it.
By February 2008, a bottom arrived for coated stents' share of the stent market. Coated stents were used in 68 percent of U.S. stent procedures in July, 66 percent in August, and then roughly 62 percent in each month for the rest of 2007, according to analysts at Millennium Research Group.
Several manufacturers are competing in this technological space. Boston Scientific offers the TAXUS stent and maintains the majority of market share with this paclitaxel-eluting stent system. According to Boston Scientific package insert information "the TAXUS Express Paclitaxel-Eluting Coronary Stent System is indicated for improving luminal diameter for the treatment of de novo lesions 28 mm in length in native coronary arteries and 2.5 to 3.75 mm in diameter. Boston Scientific has also developed the second-generation TAXUS Liberte paclitaxel-eluting stent system in the treatment of patients with coronary artery disease.
According to a company press release in December 2007, this system is available outside of the U.S. Company information indicates as a result of the expanded CE mark, the TAXUS Liberte stent system in the European Union is indicated for treatment of de novo and restenotic lesions or total occlusions in patients with coronary artery disease — angina; silent ischemia; acute myocardial infarction — to improve luminal diameter and reduce restenosis within the stent and at the stent edges in native coronary arteries. The TAXUS Liberte stent system is also indicated for patients with concomitant diabetes mellitus as well as treatment of abrupt or threatened closure in patients with failed interventional therapy.
The TAXUS Liberte stent is available outside the U.S. in a wide range of sizes to treat a diversity of vessel sizes and lesion lengths seen in patients with coronary artery disease. The company said the TAXUS Liberte stent system is pending approval by the FDA and is not available for sale in the U.S. In addition to the TAXUS and TAXUS Liberte, Boston Scientific is hopeful that the TAXUS Atom, a small vessel stent, will gain approval later this year. Boston Scientific is also awaiting approval for PROMUS, an Everolimus-eluting stent which will be co-marketed with Abbottï¿½s product, Xience V.
Abbottï¿½s Xience V was recommended for approval by the FDA on Nov. 29, 2007 and formal approval is anticipated in mid-2008. Abbott obtained Xience V when it purchased Guidant's stent business in April 2006. Xience was launched in European and other international markets in late 2006, and in March of 2008, a smaller 2.25-mm stent version received CE mark approval in Europe and selected countries in Asia and Latin America. Abbott is also conducting promising investigational work with a fully bioabsorbable everolimus-eluting stent.
Other technological leaders as well offer competitive DES platforms. Johnson and Johnson markets the Cypher, a sirolimus-eluting stent and Medtronics offers the Endeavor zotarolimus-eluting stent. The Endeavor platform combines an advanced cobalt alloy stent with a highly biocompatible polymer coating and a noncytotoxic drug.
With innovative products on the market and more on the horizon, how is a clinician to decide who are the candidates best suited for DES? Diagnostic and Invasive Cardiology had the opportunity to explore this question with experts in the field.
There are certain criteria required to qualify a patient for DES use. According to John M. Lasala, M.D., Ph.D, professor of medicine at Washington University School of Medicine and director of the interventional cardiology/cardiac catheterization laboratory at Barnes-Jewish Hospital in St. Louis, the patients best suited for DES would be the people who, number one, could take Plavix for a year because they would be more suited from a medical standpoint and a compliance standpoint. "People have to be reliable to take Plavix before we can even consider them for DES, he explained. "Once they've met that basic criteria, however, then we'd really like to optimize the benefits of DES by employing them in the highest risk settings for restenosis. So smaller vessels, longer lesion length, are potential sites - those are the people who are truly going to benefit the most because we know their baseline restenosis rate will be fairly high, in some cases as much as 40-50 percent. If we can achieve a 50-75 percent reduction in restenosis by employing DES in those areas, we have a huge potential benefit."
Lasala also said there are factors with patients that increase the risks involved with DES.
"DES is contraindicated in patients who can't take Plavix for at least a year whether it's for medical or socioeconomic reasons — or you have a known adverse reaction to any of the drugs involved (ASA, Plavix or the DES components)," he said.
Seeking Anatomical Perfection
With an understanding of which patients are best suited for DES and those in whom DES is contraindicated, we also asked the experts for the leading three "take away messages" for colleagues with respect to DES therapy. According to Lasala, "DES does not absolve you of doing the very best job mechanically that you can. Because we have such low restenosis rates to deal with the 'drop and go approach' is not appropriate since you may expose your patient to stent thrombosis. So we still have to aim for 'anatomical perfection' as much as possible. Number two is careful screening your patients as to their suitability for prolonged dual anti-platelet therapy. Number three, stay tuned. There will be changes in the platelet strategy of both to measure your patient's response to aspirin and Plavix and how to adjust those regimens."
Gregg W. Stone, M.D., professor of medicine at Columbia University College of Physicians and Surgeons, director of cardiovascular research and education at the Center for Interventional Vascular Therapy, NewYork-Presbyterian Hospital/Columbia University Medical Center commented, "Number one: the emerging data suggests that DES have similar or reduced rates of death and myocardial infarction compared to BMS in a broad cross section of patients. Therefore, number two, DES are appropriate for most patients, not all, but most patients with coronary artery disease, almost all patients who have on-label indications. And, I think we can somewhat judiciously extend that to some off-label indications that are at high risk for restenosis, but not an excessively high risk for stent thrombosis. I think we need to wait for the randomized trials before we can routinely recommend DES for acute myocardial infarction, left main disease or complex multi-vessel disease. And, finally, right now it's very important to assess your patients for their ability to take dual anti-platelet therapy for at least a year before implanting a DES."
As to which stent is really best, the physician's clinical gestalt tailored to the specific needs of that patient may still be the best guiding force for DES selection.
Stent Technology Updates as of 2017
Here are links to some recent articles on stent technologies from 2016 and 2017. The focus of stent technologies in 2017 is on bioresorbable polymers to make metallic stents into bare metal stents after a few months of being implanted. The first totally bioresorbable stent that dissolves and leaves nothing behind in the body was also cleared by the FDA in 2016. Experts also agree that for the most part, all drug-eluting stents (DES) on the U.S. market have very similar outcomes and have largely become commodities purchased by hospitals based on price rather than data showing slightly better outcomes.