A stent coated with a rapamycin biodegradable polymer was found to be non-inferior to the two leading permanent polymer-based DES platforms, according to the ISAR-TEST 4 trial. Results showed that the primary endpoint (a composite of cardiac death, MI related to the target vessel or revascularisation related to the target lesion) was reached at one year in 13.8% of patients treated with the biodegrable stent compared to 14.4% treated with the permanent polymer stent (Pnon-inferiority 0.005). The study, presented in a Hot Line session yesterday, represents the largest randomised study so far of biodegradable polymer-based DES.
Commenting on the background to the study, Julinda Mehilli from the Technische University in Munich said that a limitation of non-erodible polymers in DES is that they remain exposed to the coronary artery environment long after their useful functions have been served. Indeed, studies have implicated durable polymer residue as a cause of persistent arterial wall inflammation and delayed vascular healing. Biodegradable polymer coatings, she proposed, offer the prospect of superior drug delivery without the long-term consequences of polymer residue. The ISAR (individualizable drugeluting stent system to abrogate restenosis) team in Germany has devised a stent platform to investigate novel DES coatings.
In the open-label ISAR-TEST-4 study 2603 patients with de novo lesions recruited from two tertiary referral centres in Munich were randomly assigned to treatment with the biodegradable polymer rapamycin-eluting stent (n=1299) or permanent polymer DES (n=1304: rapamycineluting n=652; everolimus-eluting n= 652). All patients were followed for one year.
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Julinda Mehilli: "Non-inferiority of the
biodegradable compared to the permanent
polymer DES
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Results showed similar rates of all-cause death (p=0.90), all MI (P=0.84) and stent revascularisation related to the target lesion (p=0.58).
“This study shows the non-inferiority of the biodegradable polymer compared to the permanent polymer DES,” said Mehilli. “But the follow-up of one year is probably too short to reveal safety differences.”
She added that a further two year analysis is planned - and that the study represents ”real world practice”. Patients had a mean age of 67 years, one third had diabetes, 40% presented with ACS, 80% with multivessel disease, and more than 70% had complex lesions.
In an accompanying editorial published in European Heart Journal, Aron Kugelmass from Baystate Medical Center, Springfield, USA, writes: “Despite the theoretical advantages of a biodegrable polymer, this report must be viewed only as an initial encouragement for this technology. It is naïve to believe that a novel technologic breakthrough will be free of a yet to be determined new limitation.” It is critical, he added, that participants be followed long term for five years or longer).