薬剤溶出ステントと急性冠症候群

GRACE登録データ解析によると、急性冠症候群患者に対し薬剤溶出ステントはベアメタルステントと比較し慎重に使用すべきであることが示唆された

GRACE registry data analysis suggests that drug-eluting versus bare metal stents should be used with caution in patients with acute coronary syndrome

GRACE登録データ解析によると、急性冠症候群患者に対する薬剤溶出ステント使用はベアメタルステントと比較し2年後の総死亡率が高いため慎重に使用すべきであることが示唆された、とESCで発表された。Global Registry of Acute Coronary syndromEs (GRACE)では、米国、ヨーロッパ、およびオーストラリア／ニュージーランドの14ヵ国のデータを収集した。この解析ではベアメタルステントまたは1つ以上の薬剤溶出ステントを挿入された患者の2年後までの生存率を比較した。生存率は退院6ヵ月後の時点では同等であったが、その後死亡率は薬剤溶出ステント群で高かった。この差はほとんどが急性心筋梗塞に対しステントを挿入された患者によるものであり、後期の再梗塞のリスクが高く、潜在的な差が後期のステント内血栓に関連したことを示唆している。生存率の差は、患者群間のベースラインでの患者背景で補正してもなお認められた。

Analysis of GRACE registry data suggests that drug-eluting stents should be used with caution in patients with acute coronary syndrome due to increased all-cause mortality at two years compared with bare metal stents, according to a presentation at the annual meeting of the European Society of Cardiology.

Although drug-eluting stents are extremely effective in preventing restenosis following angioplasty, there has been increasing uncertainty regarding their long-term safety. Specifically, there is concern that some stents may occlude abruptly more than one year after placement due to late stent thrombosis.

Although such thrombosis is rare, probably in the range of less than 1 percent per year, it is extremely severe, with up to 45 percent mortality. Thus, the question is raised whether this rare but life-threatening event may offset the benefit achieved by drug-eluting stents in preventing restenosis.

The risk of late stent thrombosis may be greater in the context of acute coronary syndromes and, in fact, little information is available so far from rigorous randomized clinical trials comparing drug-eluting stents with bare metal stents in these patients, particularly those with acute myocardial infarction. Randomized clinical trials that have compared drug-eluting stents and bare metal stents in the context of acute myocardial infarction are relatively small (totaling fewer than 1,000 patients with drug-eluting stents) and most have only reported one year of follow-up.

The current analysis used the database from the Global Registry of Acute Coronary syndromEs (GRACE), collected in 94 hospitals in 14 countries across 4 continents (Americas, Europe, Australia/NZ) to compare survival at up to two years of patients treated with bare metal stents only or with at least one drug-eluting stent.

Survival appeared similar in at six months after discharge, but thereafter mortality was greater in patients treated with drug-eluting stents. This difference was entirely related to patients treated for acute myocardial infarction and was associated with an increased risk of late reinfarction, suggesting that it may indeed be related to late stent thrombosis.

Although caution should always be exercised when analyzing an observational study such as GRACE (in which patients who received drug-eluting stents and bare metal stents were not similar), this survival difference (which persisted after statistical adjustment for differences in baseline characteristics between the two types of patients) suggests that drug-eluting stents should be used with caution in patients with acute myocardial infarction, at least until more evidence is accumulated of long-term safety from large studies with long-term follow up.