预防非瓣膜性心房纤维颤动病患初次中风 口服抗凝血药物比抗血小板药物好


  July 27, 2007 — 根据7月18日发表在Cochrane实证医学资料库的报告,针对非瓣膜性心房纤维颤动病患预防初次中风,口服抗凝血药优于抗血小板药物治疗;这项综合分析包括8个随机对照试验,针对将近10,000名病患,发现warfarin与其它抗凝血药,相较于抗血小板治疗可减低心房纤维颤动病患发生初次中风风险达33%;而病患接受抗血小板治疗相较于未接受预防性治疗则是降低20%的风险。
  
  试验研究者,亚利桑那州斯科特斯戴尔梅约医学中心的Maria Aguilar博士向Medscape表示,如果是预防二次中风,大家都已经知道warfarin的效果比aspirin或其它抗血小板治疗好,但我们想比较初次预防的效果,结果发现针对非瓣膜性心房纤维颤动病患,warfarin及其它抗凝血剂优于抗血小板治疗。
  
  她补充表示,抗凝血剂比起抗血小板剂,包括aspirin、clopidogrel及其它抗血小板药物,可减少10到20%中风机率,根据这些结果,我们认为warfarin在初次预防中风可能是最好的选择。
  
  这项综合评论,研究员收集了所有慢性非办膜性心房纤维颤动病患长期(四周以上)、接受调整口服抗凝血药剂量、且没有其它影响因子的随机分派试验,与接受抗血小板治疗病患相比。
  
  【治疗上的挑战】
  8个临床试验共收纳9,598个不曾发生过中风、或暂时性缺血性发作的病患,进行warfarin与不等剂量aspirin(剂量范围由每天75至325毫克)的比较;平均每位受试者追踪时间是1.9年。
  
  口服抗凝血药有较低发生中风、缺血性中风及全身性血栓的风险,除此之外,作者也提到投予口服抗凝血药,能实质但未达统计差异的降低所有失能、或致命性中风以及心肌梗塞。
  
  心血管事件死亡及所有原因死亡结果在两组是相似的,抗凝血治疗组则有较高的颅内出血发生比例。
  
  Aguilar博士表示,此试验结果是可被预期的,她希望这项发现能加强医生对这群病患用抗凝血药的信心。
  
  显然的,warfarin也不是完全安全的药物,它也会造成破坏性的并发症,包括死亡;除此之外,在治疗上也是很大的挑战;Aguilar博士表示,用warfarin治疗病患需要使用抗凝血药物的临床经验、检验数据的评估及病患与家属的支持,因此大多数医师都选择抗血小板药物治疗。
  
  【唯一有效的选择】
  然而,她补充道,重点在于针对这群病患,这是预防中风唯一有效的选择,在正确服用下是安全且有效的。
  
  Aguilar博士表示,我希望这些结果能让不愿意开抗凝血药物治疗的医生能敞开心胸去面对。
  
  最后我们需要的是什么?是一种能结合warfarin的有效及aspirin的安全的制剂,目前最有希望的就是ximelagatran。
  
  希望能有一体适用的药,既能克服warfarin需要监测、药物交互作用及饮食的问题;Aguilar博士表示,但不幸的是,此药由于它的肝毒性,因此从未上市。
  
  Aguilar博士表示,针对此点,目前年老且非瓣膜性心房纤维颤动病患的数目正逐渐成长,在预防中风方面还未有新的疗法;我们应该学习去善用已经存在的抗血栓治疗方式。

Oral Anticoagulants Trump Anti

By Caroline Cassels
Medscape Medical News

July 27, 2007 — Oral anticoagulants are superior to antiplatelet therapy for primary stroke prevention in patients with nonvalvular atrial fibrillation (AF), according to a new report published in the Cochrane Database of Systematic Reviews July 18.

The meta-analysis, which included 8 randomized controlled trials and almost 10,000 patients, found warfarin and other anticoagulants reduced primary stroke risk in patients with AF by about 33% compared with antiplatelet therapies. Patients who received antiplatelet therapy had a 20% reduction in primary stroke risk compared with their counterparts who received no preventive treatment.

"When it comes to secondary stroke prevention, it's well-known warfarin is superior to aspirin or other antiplatelet therapy, but we wanted to compare the efficacy of these agents in primary prevention. We found warfarin or other anticoagulant therapy reduced the risk of stroke and other ischemic vascular events in patients with nonvalvular AF and that this effect was superior to the effect of antiplatelet therapy in this patient population," study investigator Maria Aguilar, MD, from the Mayo Clinic in Scottsdale, Arizona, told Medscape.

"Anticoagulants reduced [stroke] risk 10% to 20% more than antiplatelet therapy, including aspirin, clopidogrel, and other antiplatelet agents. Based on these results, we think warfarin is probably the best option for primary stroke prevention in patients who can take it safely," she added.

For the review, the investigators included all unconfounded, randomized trials in which long-term (more than 4 weeks), adjusted-dose oral anticoagulant treatment was compared with antiplatelet therapy in patients with chronic nonvalvular AF.

Management Challenges

The 8 trials included 9598 patients without prior stroke or transient ischemic attack (TIA) and looked at warfarin vs adjusted-dose aspirin (in doses ranging from 75 to 325 mg/day). The mean overall follow-up was 1.9 years per study participant.

Oral anticoagulants were associated with lower risk of all stroke, ischemic stroke, and systemic emboli. In addition, the authors report that all disabling or fatal strokes and myocardial infarction (MI) were substantially, but not significantly, reduced by oral anticoagulants.

Vascular death and all-cause mortality outcomes were similar between the 2 treatments; intracranial hemorrhage was increased by anticoagulant therapy.

While the study's results are not unexpected, said Dr. Aguilar, she hopes that the findings will help strengthen physicians' confidence in the benefits of anticoagulant therapy in this patient group.

Admittedly, said Dr. Aguilar, warfarin is not a benign agent and can cause devastating complications, including death. In addition, there are significant challenges associated with its management.

"Treating patients with warfarin requires an anticoagulation clinic, access to a lab, and a significant commitment from the patient and the patient's family. As a result, most general practitioners favor antiplatelet therapy," she said.

Only Available Option

Nevertheless, she added, at this point it is the only available option for stroke prevention in this patient group and, when administered correctly, is safe and effective.

"I hope these results will help clinicians who are still reluctant to use anticoagulation therapy take a more open-minded approach toward it," she said.

What is needed ultimately, she said, is an agent that combines the efficacy of warfarin with the safety of aspirin. The best recent hope for this was ximelagatran.

The one-size-fits-all drug promised to overcome the monitoring, drug interaction, and dietary issues associated with warfarin therapy. Unfortunately, said Dr. Aguilar, the agent turned out to be hepatotoxic and never made it to market.

"At this point, there are no new therapies in the pipeline to prevent stroke in this growing population of older patients with nonvalvular atrial fibrillation. We will have to learn to live with what we have and do our best to prevent stroke using existing antithrombotic therapy," she said.

Cochrane Database Syst Rev. 2007;3:CD006186.

    
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