新たな生分解性の薄いステントは有望であることが示された（Presentation #3019）
生分解性成分と超薄型スキャフォールドを組み合わせた新世代の冠動脈ステントは、現在のゴールドスタンダードと比較し有望であることが示された、とのスタディ結果が2014年European Society of Cardiology Congressホットラインセッションで発表され、同時にLancetに掲載された。現在の薬剤溶出ステントは非生分解性ポリマーでコーティングされており厚いステンレススチールストラットを有しており、この特徴と合併症率の高さが関連している。これとは対照的に、今回の治験用ステントは生分解性ポリマーと"超薄型"コバルト-クロムストラット（現在使用できるもので最も薄い）が組み合わされている。このトライアルの対象者は冠動脈疾患を有し、PCI時に治験用ステント（1,063人）または標準ステント（1,056人）を使用する群にランダムに割り付けられた。一次エンドポイントである標的病変不全は、12か月間の心臓死、標的血管領域の心筋梗塞、および臨床的に標的病変の血行再建術が必要とされたものの合計であった。トライアルは非劣性を示すようにデザインされており、それは示された（一次エンドポイントは治験群で6.5%に対し標準ステント群で6.6%）。しかし、心筋梗塞（MI）で来院した患者のサブグループにおいて、治験用ステント群は優性を示し、一次エンドポイントは3.3%しか認めなかったのに対し、標準ステント群では8.7%であった（p=0.024）。この顕著なMI患者サブグループにおける有益性に関しては、さらなる研究が必要である。
A new generation coronary artery stent that combines a biodegradable component with an ultrathin scaffold showed promising results compared with the current gold standard, in a large population of coronary artery disease patients, according to a new study.
The BIOSCIENCE trial was presented as a Hot Line at the ESC Congress 2014, and published simultaneously in The Lancet.
The experimental stent "represents the next logical step in stent refinement by combining an ultrathin platform with a polymer that completely degrades," said BIOSCIENCE investigator Thomas Pilgrim, M.D., from the Swiss Cardiovascular Center at University Hospital, in Bern, Switzerland.
For well over a decade, coronary artery stents have been "drug-eluting", meaning coated with medication to prevent re-blockage of the artery. Earlier drug-eluting stents were coated with non-biodegradable polymers and had thick stainless steel struts – both features that have been linked with an increased rate of complications.
In contrast, the experimental stent combines both a biodegradable polymer and an "ultrathin" cobalt-chromium strut – the thinnest strut currently available.
Subjects in the trial had coronary artery disease and were randomly assigned to receive either the experimental stent (n=1063) or the standard stent (n=1056) during percutaneous coronary intervention.
They were then followed for 12 months, with the primary endpoint of the study being a composite of cardiac death, heart attack caused by a re-blockage in the treated artery, and the need for revascularization of the treated artery within the study period.
The trial was designed to show non-inferiority of the experimental stent compared to the standard stent and indeed, the composite endpoint occurred in 6.5% versus 6.6% of subjects respectively.
The non-inferiority for the experimental stent is noteworthy, in that "it matched the outcomes of one of the safest and most effective new generation drug-eluting stents," explained Dr. Pilgrim.
"Because of the low event rates of contemporary stents it is becoming increasingly difficult to establish superiority of newer stents in clinical trials," he added.
However, in a subgroup of patients presenting with myocardial infarction, the experimental stent showed superiority over the standard stent, with the primary endpoint occurring in only 3.3% versus 8.7% respectively (relative risk [RR] 0.38, p=0.024).
The study was not powered to assess differences in this subgroup, "therefore we cannot exclude that these findings are due to chance alone," he said.
"But future studies will need to explore whether such differences can be reproduced in this patient population, which is at highest risk for ischemic adverse events."
The trial was an investigator-initiated study supported by an unrestricted grant from Biotronik, Bülach. Switzerland and partially funded by grants from he Swiss National Science Foundation.
Dr. Pilgrim has received travel expenses and payment for lectures from Biotronik.
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