第二世代の薬剤溶出ステントの方が安全性プロファイルが良好であることが示された

EXAMINATION：第二世代薬剤溶出ステントはベアメタルステントよりもステント血栓発現率が低い

EXAMINATION: Lower rate of stent thrombosis found with second-generation drug-eluting stent than with bare metal stent

第二世代薬剤溶出ステントXience Vはベアメタルステントよりも、ST上昇心筋梗塞（STEMI）に対しプライマリPCIを施行された患者において成績が良好で安全性プロファイルも優れているとの、急性心筋梗塞におけるXience-Vの評価（EXAMINATION：Evaluation of Xience-V stent in Acute Myocardial INfArcTION）トライアルの結果が2011年European Society of Cardiology学会で発表された。このスタディはSTEMI患者をXience V（エベロリムス溶出）またはコバルトクロミウムベアメタルステント使用群に無作為に割り付けた。一次エンドポイントは総死亡、全ての再発性心筋梗塞および1年後フォローアップ時の全ての再血行再建術の合計であった。一次エンドポイントに関しては、フォローアップ期間中の新たな血行再建術が低かったため、ベアメタルステントと比較しXience-Vによる有意な有益性は認められなかった。しかし、1年後フォローアップ時のステント血栓発現率はベアメタルステントと比較しXience Vステントにおいて低く、1年後のステント血栓発現率はXience Vステントで0.5%（確実）および0.9%（確実またはおそらく）、ベアメタルステントでそれぞれ1.9%および2.6%であった（両者ともp=0.01）。

The second generation drug-eluting stent Xience V performs well in patients having primary PCI for ST elevation myocardial infarction, and has a better safety profile than that of bare metal stents, according to results of the EXAMINATION (Evaluation of Xience-V stent in Acute Myocardial INfArcTION) trial presented at the 2011 European Society of Cardiology Congress.

The study was a randomized controlled trial with an "all-comers" design to evaluate the Xience V stent in the complex setting of STEMI and to provide data that may be applicable to the real world population.

Dr. Sabate said that the first generation drug-eluting stents (DES) had been evaluated in randomized controlled trials in the setting of STEMI, with positive results overall. However, he added, most of these trials lacked "good generalizability" to real world circumstances because of their highly selected inclusion/exclusion criteria. Moreover, no safety and efficacy data exist for the new generation of DES in this high risk group of patients with STEMI. The all-comers design of the EXAMINATION trial applied wide inclusion and few exclusion criteria, "which may result in a more representative sample of the target population".

The study was an investigator-initiated, multicenter, multinational trial involving 1498 STEMI patients randomized to either a Xience V stent (everolimus-eluting) or cobalt chromium bare metal stent. The primary endpoint was a composite of all-cause death, any recurrent myocardial infarction and any repeat revascularization at one-year follow-up. Individual components of the primary endpoint and stent thrombosis were the main secondary endpoints. Patients included in the trial represented up to 70% of all STEMI patients being attended in the centers during the recruitment period, reflecting the "real world" nature of the design.

Results presented during the Hot Line session in Paris included 98% of patients with one-year follow-up data. In terms of primary endpoint, there was a non-significant trend towards benefit with the Xience-V stent by virtue of a lower rate of new revascularizations during follow-up as compared to the bare metal stents.

In terms of safety, the rates of definite and definite/probable stent thrombosis at one-year follow-up were significantly lower with the Xience V stent as compared to the bare metal stent, accounting for 0.5% (definite) and 0.9% (definite or probable) at one year with Xience V and 1.9% and 2.6% with the bare metal stent (both p=0.01).

"These are the first 'real world' results we have from a randomized trial about the performance of the new generation drug-eluting stents in the high-risk context of STEMI," said Dr. Sabate, "and I think we can be reassured over any concerns about stent thrombosis."