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Biodegradable polymer shows no long-term benefit in heart stents

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Results question value of biodegradable polymers

The absence of incremental benefit from a stent with a biodegradable polymer compared with the second generation everolimus-eluting stent with a durable polymer in this 10-year follow-up is consistent with prior reports from medium-term follow-up. At best, drug-eluting coronary stents with a biodegradable polymer are noninferior to the current generation of those with a durable polymer. Late clinical benefit from a biodegradable polymer over a second-generation drug-eluting stent with a durable polymer remains elusive. The findings begs the public health question of whether paying a higher price for a biodegradable coronary stent with a durable-polymer is a good investment.

Dr. Sripal Bangalore, professor of medicine, New York University Mitchel L. Zoler/MDedge News

Dr. Sripal Bangalore

These 10-year results also highlight that, despite using drug-eluting stent technology that remains more or less standard of care today, the treated patients showed a staggering rate of major adverse cardiac events that exceeded 3% each year. This finding suggests an urgent need to address this residual risk through further improvements in medical therapy and stent technology.

Right now, accumulated evidence supports the notion that thinner struts are less thrombogenic than thicker struts, and that not all durable polymers are equal, with some associated with less inflammation and thrombogenicity. The next frontier for stent design seems to be ultrathin struts that are less than 70 mcm in diameter. We need to now see results from a study that compares an ultrathin-strut stent with a durable polymer against one with a biodegradable polymer.

Sripal Bangalore, MD , is an interventional cardiologist and professor of medicine at New York University. He has been a consultant or adviser to Abbott Vascular, Amgen, Biotronik, and Pfizer, and he has received research funding from Abbott Vascular. He made these comments as designated discussant for ISAR-TEST-4, and in an editorial published online concurrently with his talk (Circulation. 2018 Nov 11. doi: 10.1161/CIRCULATIONAHA.118.038378 ).



– The idea behind putting a biodegradable polymer on a drug-eluting coronary stent is that, once the antirestenosis drug elutes and the polymer that held it degrades, the bare-metal stent left behind would trigger fewer long-term episodes of in-stent thrombosis than would stents that retain their polymer coating. But 10-year follow-up from a large trial that matched two second-generation drug-eluting stents, one with a biodegradable polymer and the other with a durable polymer, showed no statistically significant difference between the two for any clinical outcome, including the incidence of in-stent thrombosis, Sebastian Kufner, MD, said at the American Heart Association scientific sessions.

Dr. Sebastian Kufner, cardiologist, German Heart Centre, Munich Mitchel L. Zoler/MDedge News

Dr. Sebastian Kufner

The potential advantage of a biodegradable polymer “is expected to occur over time,” and hence following patients for 10 or more years should start to show a clear advantage, at least for the endpoint of stent thrombosis, but that didn’t happen. After a median follow-up of 10.6 years, the cumulative rate of definite or probable stent thrombosis was 1.8% among 1,299 patients who received a sirolimus-eluting stent with a biodegradable polymer (Yukon Choice) and 2.5% among 652 patients who received a second-generation everolimus-eluting stent with a durable polymer (Xience), a difference that was not statistically significant, reported Dr. Kufner, a cardiologist at the The German Heart Centre in Munich.

These two stents also produced comparable 10-year outcomes that showed no statistically significant differences for the outcomes of all-cause death, MI, need for target-lesion revascularization, or the combined incidence of all three of these outcomes. In contrast, both of these second-generation stents showed statistically significant improvements in the combined cardiac endpoint, as well as in all-cause death, and definite stent thrombosis compared with the 652 patients who received the first-generation sirolimus-eluting stent Cypher. Concurrently with Dr. Kufner’s report, the results appeared in an article online (Circulation. 2018 Nov 11. doi: 10.1161/CIRCULATIONAHA.118.038065).

Another notable finding from the 10-year follow-up was the poor prognosis these patients faced after their interventions, including the patients who received second-generation drug-eluting stents. The 10-year rate of all cause death was 30% among patients who received Xience stents, 32% among those treated with Yukon Choice stents, and 37% among patients treated with Cypher stents.

“I’m daunted by this 10-year mortality rate even with the best current drug-eluting stents,” said Roxana Mehran, MD, professor of medicine at Icahn School of Medicine at Mount Sinai in New York and a cochair of the session. “I’m depressed about this as an interventionalist. We need to do better, although it might not just be about the revascularization.” The high mortality in these patients after 10 years may also reflect a lack of optimal medical treatment in some, she suggested.

Dr. Roxana Mehran, professor of medicine at Icahn School of Medicine at Mount Sinai in New York

Dr. Roxana Mehran

The ISAR-TEST-4 (Intracoronary Stenting and Angiographic Results: Test Efficacy of 3 Limus-Eluting Stents) trial randomized 2,603 patients during the period of September 2007–August 2008 at either of two centers in Munich. The study’s primary endpoint was the combined rate of cardiac death, MI, and target-lesion revascularization by 12 months after treatment. The 12-month results showed a similar 14% rate of this combined endpoint in the subgroup of patients treated with the biodegradable-polymer stent and in those treated with stents that used durable polymers, which proved the noninferiority of the stent with a biodegradable polymer (Eur Heart J. 2009 Oct 1;30[20]:2441-9). This initial analysis combined the patients who received Cypher and Xience stents into one comparator group: patients who received stents with durable polymers.

The new, long-term follow-up analysis included 2,153 patients (83%) followed for at least 10 years after their intervention.

ISAR-TEST-4 received no commercial funding. Dr. Kufner had no disclosures. Dr. Mehran has an ownership interest in Claret Medical and Elixir Medical, has been a consultant or adviser to Abbott Laboratories, Boston Scientific, Bristol-Myers Squibb, Janssen, Roivant Sciences, and Siemens Medical Solutions, and has received research funding from several companies.

SOURCE: Kufner S et al. AHA scientific sessions, Abstract 18630.

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