Griffin Glenn
United Arab Emirates University, Faculty of Medicine and Health Sciences, Al Ain, United Arab Emirates.
Am Fam Physician. 2005 Mar 1;71(5):897-9.
Elevated systemic blood pressure results in high intravascular pressure. The main complications, coronary heart disease, ischemic strokes, and peripheral vascular disease, are related to thrombosis rather than hemorrhage. Some complications related to elevated blood pressure, heart failure, and atrial fibrillation are associated with stroke and thromboembolism. It seems plausible that antithrombotic therapy may be particularly useful in preventing thrombosis-related complications of elevated blood pressure.
To conduct a systematic review of the role of antiplatelet therapy and anticoagulation in patients with hypertension, including those with elevations in systolic and diastolic blood pressure and those with isolated elevations of systolic or diastolic blood pressure. The following hypotheses were addressed: (1) antiplatelet agents reduce total deaths and major thrombotic events compared with other active treatment or placebo; and (2) oral anticoagulants reduce total deaths and major thromboembolic events compared with other active treatment or placebo.
The authors' studied reference lists of articles found by searching electronic databases (MEDLINE, EMBASE, DARE) and abstracts from national and international cardiovascular meetings. Relevant authors of these studies were contacted to obtain further data.
Randomized controlled trials (RCTs) in patients with elevated blood pressure were included if they were of at least three months' duration and compared antithrombotic therapy with other active treatment or placebo.
Data were independently collected and verified by two reviewers. Data from different trials were pooled when appropriate.
The Antiplatelet Trialists' Collaboration meta-analysis of antiplatelet therapy for secondary prevention in patients with elevated blood pressure reported a 4.1 percent absolute reduction in vascular events compared with placebo. Data on the patients with elevated blood pressure from the 29 individual trials were requested but could not be obtained. Three additional trials met the inclusion criteria and were included. Acetylsalicylic acid (ASA) did not reduce stroke or "all cardiovascular events" compared with placebo in primary prevention patients with elevated blood pressure and no prior cardiovascular disease. In one large trial (the Hypertension Optimal Treatment trial), ASA taken for five years reduced rates of myocardial infarction (MI) (absolute risk reduction, 0.5 percent; number needed to treat [NNT], 200 for five years), increased rates of major hemorrhage (absolute risk increase, 0.7 percent; NNT, 154), and did not reduce all-cause mortality or cardiovascular mortality. In the Clopidogrel vs. Aspirin in Patients at Risk of Ischemic Events trial, there was no significant difference between ASA and clopidogrel for the composite end point of stroke, MI, or vascular death. In two small trials, warfarin alone or in combination with ASA did not reduce rates of stroke or coronary events.
REVIEWERS' CONCLUSIONS: Antiplatelet therapy with ASA cannot be recommended for primary prevention of vascular events in patients with elevated blood pressure, because the magnitude of benefit--a reduction in rates of MI--is negated by a harm of similar magnitude, an increase in rates of major hemorrhage. Antiplatelet therapy is recommended for secondary prevention in patients with elevated blood pressure because the magnitude of the absolute benefit is many times greater. Warfarin therapy alone or in combination with aspirin in patients with elevated blood pressure cannot be recommended because of lack of demonstrated benefit. Glycoprotein IIb/IIIa inhibitors, as well as ticlopidine and clopidogrel, have not been evaluated sufficiently in patients with elevated blood pressure. Further trials of antithrombotic therapy with complete documentation of all benefits and harms are needed in patients with elevated blood pressure.
全身血压升高会导致血管内压力升高。主要并发症，如冠心病、缺血性中风和外周血管疾病，与血栓形成有关，而非出血。一些与血压升高相关的并发症，如心力衰竭和心房颤动，与中风和血栓栓塞有关。抗血栓治疗在预防血压升高相关的血栓形成并发症方面可能特别有用，这似乎是合理的。
对高血压患者抗血小板治疗和抗凝治疗的作用进行系统评价，包括收缩压和舒张压均升高的患者以及单纯收缩压或舒张压升高的患者。探讨以下假设：（1）与其他活性治疗或安慰剂相比，抗血小板药物可降低总死亡人数和主要血栓事件；（2）与其他活性治疗或安慰剂相比，口服抗凝剂可降低总死亡人数和主要血栓栓塞事件。
作者研究了通过检索电子数据库（MEDLINE、EMBASE、DARE）找到的文章的参考文献列表以及国家和国际心血管会议的摘要。联系这些研究的相关作者以获取更多数据。
纳入血压升高患者的随机对照试验（RCT），试验持续时间至少为三个月，并将抗血栓治疗与其他活性治疗或安慰剂进行比较。
数据由两名审阅者独立收集和核实。适当时将不同试验的数据进行合并。
抗血小板治疗协作组对血压升高患者二级预防的抗血小板治疗进行的荟萃分析表明，与安慰剂相比，血管事件的绝对降低率为4.1%。已要求提供29项个体试验中血压升高患者的数据，但未获得。另外三项试验符合纳入标准并被纳入。在无既往心血管疾病的血压升高的一级预防患者中，与安慰剂相比，乙酰水杨酸（ASA）并未降低中风或“所有心血管事件”。在一项大型试验（高血压最佳治疗试验）中，服用五年ASA可降低心肌梗死（MI）发生率（绝对风险降低0.5%；五年所需治疗人数[NNT]为200），增加大出血发生率（绝对风险增加0.7%；NNT为154），且未降低全因死亡率或心血管死亡率。在缺血性事件风险患者中氯吡格雷与阿司匹林对比试验中，对于中风、MI或血管死亡的复合终点，ASA与氯吡格雷之间无显著差异。在两项小型试验中，单独使用华法林或与ASA联合使用均未降低中风或冠状动脉事件发生率。
不推荐使用ASA进行抗血小板治疗来预防血压升高患者的血管事件，因为获益程度（MI发生率降低）被类似程度的危害（大出血发生率增加）抵消。推荐对血压升高患者进行二级预防时使用抗血小板治疗，因为绝对获益程度要大很多倍。由于未证明有益，不推荐单独使用华法林治疗或在血压升高患者中与阿司匹林联合使用。糖蛋白IIb/IIIa抑制剂以及噻氯匹定和氯吡格雷在血压升高患者中的评估尚不充分。血压升高患者需要进一步进行抗血栓治疗试验，并完整记录所有获益和危害情况。
