Antithrombotic therapy in hypertension: a Cochrane Systematic review

Use of antiplatelet agents in patients with atherosclerotic disease

Platelets play a key role in the initiation of hemostatic mechanisms during vascular injury. When contemplating prescription of antiplatelet agents (APAs) for patients as primary prevention for cardiovascular events, the physician should carefully weigh the potential benefits of cardiovascular risk reduction with the likelihood of harm, related mostly to hemorrhagic complications. The role of APAs in secondary prevention of atherosclerosis and coronary artery disease is well established, however, optimal duration of therapy and intensity of patient treatment are not settled and probably need to be individualized per patient. We describe the data emerging from contemporary trials on the efficacy and safety of the use of oral APAs in various patient subpopulations. We also discuss the advantages and potential roles of new APAs during and following acute coronary syndromes, percutaneous coronary interventions, and symptomatic atherosclerosis. We propose certain strategies and directions for future research to enhance the safety and efficacy prevention by optimizing the beneficial effects of APAs along with other contemporary treatment modalities of primary and secondary prevention.

Protocol for assessing the hypotensive effect of evening administration of acetylsalicylic acid: study protocol for a randomized, cross-over controlled trial

BACKGROUND

The objective of this study is to evaluate the antihypertensive effect of bedtime administration of low doses of aspirin in patients with treated hypertension and high cardiovascular risk on low-dose aspirin for secondary prevention, in order to optimize their usual treatment and reduce their cardiovascular risk.

METHODS/DESIGN

This is a prospective phase IV multicentre, randomised, triple-blind, placebo-controlled, cross-over clinical trial. We will include 258 individuals with hypertension treated with low-dose aspirin for secondary prevention. These patients will be randomly recruited, by approximately 40 primary care physicians collaborating in the study, mainly in the Guipúzcoa West, Bilbao and Barcelona areas. The 258 patients will be randomly allocated to treatments to create two comparable groups. In the first period, the intervention group will take aspirin at night and placebo in the morning, while the control group will take their aspirin in the morning and placebo in the evening for 2 months. After a washout period of 15 to 30 days, there will be a second 2-month period for which groups will swap treatments. Participants will undergo ambulatory blood pressure monitoring at baseline, at the end of first period and then again at the beginning and end of the second period. The main outcome measure is the change in mean blood pressure over 24 h, and as secondary outcomes we will also assess changes in systolic and diastolic blood pressure, during the day and night, and the relationship between them. Lastly, we will explore whether non-dipper patients convert into dippers with the intervention.

DISCUSSION

The goal of this research is to provide the scientific basis for indicating a change in the time of aspirin administration from morning to evening, by primary health practitioners, to improve the patient control of blood pressure and more effectively reduce their cardiovascular risk, by combining this hypotensive effect with the well-known anti-platelet effect of low-dose aspirin.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01741922.

Antiplatelet effects of Cyperus rotundus and its component (+)-nootkatone

ETHNOPHARMACOLOGICAL RELEVANCE

Cyperus rotundus, a well-known oriental traditional medicine, has been reported to exhibit wide spectrum activity in biological systems including the circulatory system, however, little information is available on its antiplatelet activity. This study was undertaken to investigate the antiplatelet effects of Cyperus rotundus EtOH extract (CRE) and its constituent compounds.

MATERIALS AND METHODS

The antiplatelet activities of CRE and its eight constituent compounds were evaluated by examining their effects on rat platelet aggregations in vitro and ex vivo, and on mice tail bleeding times.

RESULTS

During the in vitro platelet aggregation study, CRE showed significant and concentration-dependent inhibitory effects on collagen-, thrombin-, and/or AA-induced platelet aggregation. Of its eight components, (+)-nootkatone was found to have the most potent inhibitory effect on collagen-, thrombin-, and AA-induced platelet aggregation. In addition, CRE- and (+)-nootkatone-treated mice exhibited significantly prolonged bleeding times. Furthermore, (+)-nootkatone had a significant inhibitory effect on rat platelet aggregation ex vivo.

CONCLUSIONS

This study demonstrates the antiplatelet effects of CRE and its active component (+)-nootkatone, and suggests that these agents might be of therapeutic benefit for the prevention of platelet-associated cardiovascular diseases.

Antiplatelet agents versus control or anticoagulation for heart failure in sinus rhythm

BACKGROUND

Morbidity and mortality in patients with symptomatic chronic heart failure is high, it predisposes to stroke and thromboembolism which in turn contribute to high mortality in heart failure.

OBJECTIVES

To determine effect of antiplatelet agents when compared to placebo or anticoagulant therapy on death and/or major thromboembolic events in adults with heart failure who are in sinus rhythm.

SEARCH STRATEGY

Systematic search of electronic databases (MEDLINE, EMBASE, DARE). Abstracts from cardiology meetings and reference lists of relevant papers were searched. Authors of studies were contacted for further information.

SELECTION CRITERIA

Randomised parallel group placebo or controlled trials comparing antiplatelet therapy with control or anticoagulation in adults with chronic heart failure in sinus rhythm. Treatment for at least 1 month. To assess any adverse effects cohort study & non-randomised controlled studies were assessed. Orally administered antiplatelet agents e.g. non-steroidal anti-inflammatory agents, TICLOPIDINE, CLOPIDOGREL, DIPYRIDAMOLE, ASPIRIN compared with anticoagulant agents e.g. COUMARINS, WARFARIN or placebo.

DATA COLLECTION AND ANALYSIS

Data were extracted by two reviewers independently. No meta-analyses were performed as no data were available from randomised comparisons. The data extracted included data relating to the complexities of the topic area, such as patient characteristics and concomitant treatments, as well as data relating to study eligibility, quality, and outcomes. Non-randomised studies were used to identify side-effects caused by anticoagulants.

MAIN RESULTS

One RCT of warfarin, aspirin versus no antithrombotic therapy was found but no definitive data have yet been published. Three retrospective, non-randomised cohort studies from the V-HeFT, SOLVD and SAVE trials examining the role of ACE inhibitors have examined the role of aspirin therapy +/- anticoagulant therapy in patients with heart failure and/or left ventricular systolic dysfunction. The results from these trials were conflicting.

REVIEWER'S CONCLUSIONS

At present there is no evidence from long term RCTs to recommend use of aspirin to prevent thromboembolism in patients with heart failure in sinus rhythm. A possible interaction with ACE inhibitors may reduce the efficacy of aspirin, although this evidence is from retrospective analyses of trial cohorts. There is also no evidence to indicate superior effects from oral anticoagulation, when compared to aspirin, in patients with heart failure in sinus rhythm.