FDA: Thrombosis Risk With DES Does not Outweigh Benefit

　　最近一些试验并没有发现DES增加死亡和心肌梗死，FDA循环系统器械顾问委员会认为对DES 支架血栓的担心并不会导致废弃使用DES。FDA心血管系统器械评估官员Andrew Farb讨论该委员会的建议，回顾了两种FDA 批准的DES即强生的CYPHER和波士顿科学公司的Taxus相关血栓事件危险、时间以及发生率。

　　该委员会2006年12月得出的决议是血栓形成的风险并没有超过DES治疗的益处，Farb说，“两种支架置入1年后和裸金属支架相比，DES支架血栓发生率有轻度的增加，但是支架血栓危险的增加并没有增加心肌梗死和死亡率。”

　　额外的分析

　　DES的血栓危险增加但死亡率和心肌梗死发生率并不增加的原因还需要进一步分析，他给了几个可能的解释，“研究的样本量小，不足以发现死亡率和心肌梗死在两治疗组间的差异；另外药物洗脱支架有更低的支架再狭窄和更少的再血管化治疗，可能降低死亡率和心肌梗死发生率。“Farb认为还需要更大规模更长期的随访的试验。

　　获批后研究

　　几个DES 获批后研究正在进行，这些试验可能会影响到FDA的决策。Farb说这几个试验将确定支架置入1年之后的5年中每12个月期间的支架血栓、死亡和心肌梗死发生率。“这些试验是研究真实世界中高危亚组患者的不良事件，也将为临床实践中的药物治疗、二联抗血小板治疗提供更多的信息。”

　　（武警总医院　韩玮　编译）

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FDA: Thrombosis Risk With DES Does not Outweigh Benefit

Recent trials have not found increased risk of death or MI with DES.

Concerns about stent thrombosis should not deter use of DES, an FDA Circulatory System Devices Advisory Panel has concluded.

Andrew Farb, MD, of the Office of Device Evaluation at the FDA’s Division of Cardiovascular Devices, discussed the recommendations of the panel, which re¬viewed the risks, timing, and incidence of thrombosis associated with the two approved DES – Cypher (Cordis, Johnson & Johnson) and Taxus (Boston Scientific).

The advisory panel, which met in December 2006, determined that the risk of thrombosis did not outweigh the benefits of treatment with DES. “Both approved drug-eluting stents are associated with a small increase in stent thrombosis compared with bare-metal stents that emerges 1 year after implantation,” Farb said. “However, the increased risk of stent thrombosis was not associated with an increased risk of death or myocardial infarction vs. [patients treated with] bare-metal stents.”

Additional analysis

More information is needed to assess why there may be an increased risk of thrombosis but no increased risk of mortality or MI in patients treated with DES. Several explanations are possible, he said.

“Sample sizes in the pooled studies may not have been large enough to detect a death or myocardial infarction difference between treatment groups,” Farb said.

“Also, increases in death or myocardial infarction among patients treated with drug-eluting stents might have been offset by fewer events associated with in-stent restenosis and additional revascularization procedures.”

Farb said that larger premarket clinical trials and longer follow-up are needed.

Postapproval studies

Postapproval studies of DES are ongoing, and will impact future FDA decisions. According to Farb, these studies will determine the rate of stent thrombosis, MI, and mortality during the first year following implantation and then in 12-month intervals out to 5 years.

“These studies will monitor higher-risk patient subgroups for potential safety signals in real-world use,” Farb said. “The studies will also provide additional insight into prescribing practices for, and actual patient use of, dual antiplatelet therapy.”Andrew Farb, MD