Second European Stroke Prevention Study: antiplatelet therapy is effective regardless of age. ESPS2 Working Group

Efficacy and safety of dual antiplatelet therapy in the elderly for stroke prevention: a subgroup analysis of the CHANCE-2 trial

OBJECTIVES

Evidence of the optimal antiplatelet therapy for elderly patients who had a stroke is limited, especially those elder than 80 years. This study aimed to explore the efficacy and safety of dual antiplatelet therapy (DAPT) in old-old patients compared with younger patients in the ticagrelor or Clopidogrel with aspirin in High-risk patients with Acute Non-disabling Cerebrovascular Events-II (CHANCE-2) trial.

METHODS

CHANCE-2 was a randomised, double-blind, placebo-controlled trial in China involving patients with high-risk transient ischaemic attack or minor stroke with CYP2C19 loss-of-function alleles. In our substudy, all enrolled patients were stratified by age: old-old (≥80 years), young-old (65-80 years) and younger (<65 years). The primary outcomes were stroke recurrence and moderate to severe bleeding within 90 days, respectively.

RESULTS

Of all the 6412 patients, 406 (6.3%) were old-old, 2755 (43.0%) were young-old and 3251 (50.7%) were younger. Old-old patients were associated with higher composite vascular events (HR 1.41, 95% CI 1.00 to 1.98, p=0.048), disabling stroke (OR 2.43, 95% CI 1.52 to 3.88, p=0.0002), severe or moderate bleeding (HR 8.40, 95% CI 1.95 to 36.21, p=0.004) and mortality (HR 7.56, 95% CI 2.23 to 25.70, p=0.001) within 90 days. Ticagrelor-aspirin group was associated with lower risks of stroke recurrence within 90 days in younger patients (HR 0.68, 95% CI 0.51 to 0.91, p=0.008), which was no differences in old-old patients.

CONCLUSION

Elderly patients aged over 80 in CHANCE-2 trial had higher risks of composite vascular events, disabling stroke, severe or moderate bleeding and mortality within 90 days. Genotype-guided DAPT might not be as effective in old-old patients as in younger ones.

TRIAL REGISTRATION NUMBER

NCT04078737.

Drugs targeting adenosine signaling pathways: A current view

Adenosine is an endogenous nucleoside that regulates many physiological and pathological processes. It is derived from either the intracellular or extracellular dephosphorylation of adenosine triphosphate and interacts with cell-surface G-protein-coupled receptors. Adenosine plays a substantial role in protecting against cell damage in areas of increased tissue metabolism and preventing organ dysfunction in pathological states. Targeting adenosine metabolism and receptor signaling may be an effective therapeutic approach for human diseases, including cardiovascular and central nervous system disorders, rheumatoid arthritis, asthma, renal diseases, and cancer. Several lines of evidence have shown that many drugs exert their beneficial effects by modulating adenosine signaling pathways but this knowledge urgently needs to be summarized, and most importantly, actualized. The present review collects pharmaceuticals and pharmacological or diagnostic tools that target adenosine signaling in their primary or secondary mode of action. We overviewed FDA-approved drugs as well as those currently being studied in clinical trials. Among them are already used in clinic A2A adenosine receptor modulators like istradefylline or regadenoson, but also plenty of anti-platelet, anti-inflammatory, or immunosuppressive, and anti-cancer drugs. On the other hand, we investigated dozens of specific adenosine pathway regulators that are tested in clinical trials to treat human infectious and noninfectious diseases. In conclusion, targeting purinergic signaling represents a great therapeutic challenge. The actual knowledge of the involvement of adenosinergic signaling as part of the mechanism of action of old drugs has open a path not only for drug-repurposing but also for new therapeutic strategies.

Insights from Experiences on Antiplatelet Drugs in Stroke Prevention: A Review

Reduction of hazard risk of cerebral ischemic event (stroke, transient ischemic attack (TIA)) represents the hard point to be achieved from primary or secondary preventive strategy in the best clinical practice. However, results from clinical trials, recommendations, guidelines, systematic review, expert opinions, and meta-analysis debated on the optimal pharmacotherapy to achieve the objective. Aspirin and a number of antiplatelet agents, alone or in combination, have been considered from large trials focused on stroke prevention. The present review summarizes, discusses results from trials, and focuses on the benefits or disadvantages originating from antiplatelet drugs. Sections of the review were organized to show both benefits or consequences from antiplatelet pharmacotherapy. Conclusively, this review provides a potential synopsis on the most appropriate therapeutic approach for stroke prevention in clinical practice.

Progress in the development of antiplatelet agents: Focus on the targeted molecular pathway from bench to clinic

Antiplatelet drugs serve as a first-line antithrombotic therapy for the management of acute ischemic events and the prevention of secondary complications in vascular diseases. Numerous antiplatelet therapies have been developed; however, currently available agents are still associated with inadequate efficacy, risk of bleeding, and variability in individual response. Understanding the mechanisms of platelet involvement in thrombosis and the clinical development process of antiplatelet agents is critical for the discovery of novel agents. The functions of platelets in thrombosis are regulated by two major mechanisms: the interaction between surface receptors and their ligands, and the downstream intracellular signaling pathways. Recently, most of the progress made in antiplatelet drug development has been achieved with P2Y receptor antagonists. Additionally, the usage of GP IIb/IIIa receptor antagonists has decreased, because it is associated with a higher risk of bleeding and thrombocytopenia. Agents targeting other platelet surface receptors such as PARs, TP receptor, EP3 receptor, GPIb-IX-V receptor, P-selectin, as well as intracellular signaling factors, such as PI3Kβ, have been evaluated in an attempt to develop the next generation of antiplatelet drugs, reduce or eliminate interpatient variability of drug efficacy and significantly lower the risk of drug-induced bleeding. The aim of this review is to describe the pathways of platelet activation in thrombosis, and summarize the development process of antiplatelet agents, as well as the preclinical and clinical evaluations performed on these agents.

[Difficult decisions in stroke therapy]

In numerous situations stroke physicians face a lack of evidence during their daily practice. In this report the authors address some of the difficult treatment decisions encountered in acute therapy and secondary prevention. Examples include off-label thrombolysis and prevention in high-risk situations. The available data from trials and registries are discussed, and personal views and recommendations are expressed.

Secondary prevention of stroke in the elderly: a review of the evidence

BACKGROUND

Stroke is a major health problem with significant impact on the affected individuals and the whole community. In light of stroke being the leading cause of disability, the ageing of the population and the high incidence of stroke among the elderly, highlight the importance of primary and secondary prevention interventions among this group. The elderly generally have been underrepresented in clinical trials, creating many uncertainties and less optimal medical care for this group of patients.

OBJECTIVE

This review aims to make evidence-based management recommendations for secondary stroke prevention in the elderly.

METHODS

Secondary prevention-related primary literature was identified using MEDLINE and PubMed (1982 to present) with combinations of the following search terms being employed: antiplatelets, aspirin, atrial fibrillation, elderly, geriatrics, hypertension, lipids, secondary prevention, statins, stroke, and warfarin. In addition, the references of these articles were also reviewed.

RESULTS

Twenty-three clinical trials were included in this review, covering different aspects of secondary stroke prevention. Many of these trials were not specifically limited to the elderly, but conclusions related to their care can be derived from them. Although the American Heart Association/American Stroke Association guidelines suggest an equal benefit of aspirin, aspirin/dipyridamole, and clopidogrel in secondary prevention, the use of aspirin in the elderly may be preferred for reasons related to compliance and experience. Warfarin was largely avoided in the management of elderly stroke patients in the past, although available evidence demonstrates its efficacy and safety as a first choice for elderly patients with atrial fibrillation and presumed cardiac source of emboli. Lowering blood pressure among the elderly is an important aspect of secondary stroke prevention and can be achieved with the same agents used among younger age groups with a preference for a thiazide diuretic/angiotensin-converting enzyme inhibitor combination that has proven efficacy among elderly patients. Available evidence supports the use of statins among elderly patients with history of stroke or transient ischemic attack (TIA), and the derived benefit of treatment does not differ significantly from that in the younger age group. Elderly patients with 50% to 99% carotid artery stenosis and history of stroke or TIA should be considered for early carotid endarterectomy to reduce recurrent stroke.

CONCLUSION

Age should not be considered a barrier for the provision of optimal secondary prevention interventions. The available evidence supports similar and sometimes superior derived benefit from secondary preventive stroke measures in the elderly compared with that seen in younger patients.

Potentially inappropriate prescribing in an Irish elderly population in primary care

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* Potentially inappropriate prescribing in older people is a well-documented problem and has been associated with adverse drug reactions and hospitalization. * Beers' criteria, Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) and Screening Tool to Alert doctors to Right Treatment (START) are screening tools that have been formulated to help physicians and pharmacists identify potentially inappropriate prescribing and potential prescribing omissions. * The prevalence of potentially inappropriate prescribing and prescribing omissions in the elderly population presenting to hospital with acute illness is high according to STOPP and START criteria.

WHAT THIS STUDY ADDS

* Potential errors of prescribing and of omission of medicines are prevalent among medically stable older people in primary care. * Screening tools should be incorporated into the everyday practice of primary care doctors and community pharmacists as a means of preventing potential errors of prescribing commission and prescribing omission in older people.

AIMS

Screening tools have been formulated to identify potentially inappropriate prescribing (IP) in older people. Beers' criteria are the most widely used but have disadvantages when used in Europe. New IP screening tools called Screening Tool of Older Person's Prescriptions (STOPP) and Screening Tool to Alert doctors to Right Treatment (START) have been developed to identify potential IP and potential prescribing omissions (PPOs). The aim was to measure the prevalence rates of potential IP and PPOs in primary care using Beers' criteria, STOPP and START.

METHODS

Case records of 1329 patients >or=65 years old from three general practices in one region of southern Ireland were studied. The mean age +/- SD of the patients was 74.9 +/- 6.4 years, 60.9% were female. Patients' current diagnoses and prescription medicines were reviewed and the Beers' criteria, STOPP and START tools applied.

RESULTS

The total number of medicines prescribed was 6684; median number of medicines per patient was five (range 1-19). Overall, Beers' criteria identified 286 potentially inappropriate prescriptions in 18.3% (243) of patients, whilst the corresponding IP rate identified by STOPP was 21.4% (284), in respect of 346 potentially inappropriate prescriptions. A total of 333 PPOs were identified in 22.7% (302) of patients using the START tool.

CONCLUSION

Potentially inappropriate drug prescribing and errors of drug omission are highly prevalent among older people living in the community. Prevention strategies should involve primary care doctors and community pharmacists.

[Variable platelet response to aspirin and new therapeutic targets]

Aspirin is the first-line oral antiplatelet drug to prevent thromboembolic arterial occlusions. Aspirin irreversibly inhibits cyclooxygenase (COX) 1 involved in the platelet production of thromboxane (TX) A(2), an inducer of vasoconstriction and a platelet activating agent. Recurrent vascular events despite aspirin intake, combined with laboratory evidence of poor antiplatelet effect, suggested what has been called "aspirin resistance". For clarity's sake a real aspirin resistance would be the absence of COX1 inhibition due to intrinsic platelet factors (which has never been reported). What has been described is (expected) variability. COX1 inhibition can be insufficient to modify TX-dependent platelet behaviour. Other agonists, the production of which does not involve COX1, can stimulate TX-receptors. The antiplatelet effect of aspirin can be insufficient for pharmacokinetic or pharmacodynamic reasons, the latter being further classified as TX-dependent or not. If platelets are so reactive that responses are more TX-independent than normally, then neither aspirin nor any drugs acting on this pathway can do the job. These mechanisms should be better understood and diagnosed, and this is the prerequisite for the development of newer antiplatelet agents.

Complete occlusion of extracranial internal carotid artery: clinical features, pathophysiology, diagnosis and management

A complete occlusion of the internal carotid artery (ICA) is an important cause of cerebrovascular disease. A never-symptomatic ICA occlusion has a relatively benign course, whereas symptomatic occlusion increases future risk of strokes. Ultrasonography, magnetic resonance imaging and contrast angiography are useful diagnostic tests, and functional imaging of the brain (eg, with positron emission tomography) helps to understand haemodynamic factors involved in the pathophysiology of brain ischaemia. Recently, there has been a resurgence of interest in the role of extracranial-intracranial bypass surgery for the treatment of completely occluded ICA. With advances in the measurement of cerebral haemodynamics, it may be possible to identify high-risk patients who could benefit from the bypass surgery.

Dipyridamole may induce migraine in patients with migraine without aura

Dipyridamole inhibits phosphodiesterase 5 (PDE5) and adenosine re-uptake. The most prominent side-effect is headache. We examined the migraine-generating effects of dipyridamole as well as the cerebral blood velocity response in a single-blind study, including 10 patients with migraine without aura and 10 healthy subjects. Dipyridamole 0.142 mg/kg per min was administered intravenously. Headache intensity was scored on a verbal rating scale along with pain characteristics and accompanying symptoms. Blood velocity in the middle cerebral artery (V(mca)), blood pressure and heart rate were recorded repeatedly. Headache was induced in all migraine patients and in eight of 10 healthy subjects (P = 0.47) with no significant difference in headache intensity (P = 0.53). However, five patients but only one healthy subject experienced the symptoms of migraine without aura, according to ICHD-2 criteria, within 12 h (P = 0.14). Four patients reported photophobia after dipyridamole compared with no healthy subjects (P = 0.087). V(mca) decreased (P < 0.001) during and after dipyridamole infusion with no difference between groups (P = 0.15) coinciding with initiation, but not cessation of immediate headache. Thus, dipyridamole induces symptoms of migraine and an initial decrease in V(mca) in migraine patients, but not significantly more than in healthy subjects. This relatively low frequency of migraine induction, compared with nitric oxide donors and sildenafil, is probably due to the less specific action of dipyridamole on the cGMP signalling pathway as well as a possible bidirectional effect of adenosine on migraine induction.

Stroke prevention with aspirin, warfarin and ximelagatran in patients with non-valvular atrial fibrillation: A systematic review and meta-analysis

OBJECTIVE

To compare the effectiveness of aspirin, warfarin, and ximelagatran as thromboprophylaxis in patients with non-valvular atrial fibrillation (NVAF).

METHODS

Systematic review of randomised controlled trials in patients with NVAF treated with adjusted-dose warfarin and aspirin, fixed low-dose (FLD) warfarin, ximelagatran or placebo. Outcome measures studied were ischaemic stroke, systemic embolism, mortality and haemorrhage. Meta-analysis was performed using a fixed effects model.

RESULTS

We identified 13 trials (n=14,423 participants) of sufficient quality to be included in the analysis. Adjusted-dose warfarin significantly reduced the risk of ischaemic stroke or systemic embolism compared with aspirin (relative risk [RR] 0.59; 95% confidence interval [CI]: 0.40 to 0.86), FLD warfarin (RR 0.36; 95% CI: 0.23 to 0.58), or placebo (RR 0.33; 95% CI: 0.24 to 0.45). However, aspirin and placebo had a lower risk of major bleeding compared to warfarin (RR 0.58; 95% CI: 0.35 to 0.97 and RR 0.45; 95% CI: 0.25 to 0.82, respectively). The oral direct thrombin inhibitor, ximelagatran was as effective as adjusted-dose warfarin in the prevention of ischaemic strokes or systemic emboli (RR 1.04; 95% CI: 0.77 to 1.40) with less risk of major bleeding (RR 0.74; 95% CI: 0.56 to 0.96). Adjusted-dose warfarin significantly reduced mortality compared to placebo (RR 0.69; 95% CI: 0.53 to 0.89), but not for any of the other comparisons (aspirin: RR 0.87; 95% CI: 0.67 to 1.13; FLD warfarin: RR 1.11; 95% CI: 0.81 to 1.52; ximelagatran: RR 1.04; 95% CI: 0.86 to 1.26).

CONCLUSIONS

We have extended previous analyses, making this the largest systematic review and meta-analysis of thromboprophylaxis trial data in AF--and have included recent trials with the new oral direct thrombin inhibitor, ximelagatran. This systematic review confirms the superiority of anticoagulation therapy over aspirin as thromboprophylaxis in patients with NVAF. The new oral direct thrombin inhibitor, ximelagatran, appears as effective as adjusted-dose warfarin for the prevention of thromboembolic events in NVAF, with a lower risk of bleeding.

Long-term management of atherothrombosis

While clinical trials of specific antithrombotic agents can reduce the risk of vascular events in at-risk patients, understanding the results of these studies is key to optimizing benefit and minimizing risk.

Alternatives to warfarin for thromboembolism prophylaxis in nonrheumatic atrial fibrillation

Decision-making regarding thromboembolism prophylaxis in atrial fibrillation remains a major clinical challenge. While evidence of the beneficial effect of anticoagulation for patients participating in clinical trials is well established, only half of eligible individuals in the general population are currently treated with warfarin. Using an evidence-based approach, this review covers major therapeutic approaches in practice today and many of those expected to be released in the near future. Pharmacologic agents evaluated include warfarin, aspirin, other antiplatelets agents, direct thrombin inhibitors and antiarrhythmic drugs. Nonpharmacologic treatments reviewed include surgical and catheter ablation, pacing, left atrial appendage ligation and occlusion methods, and atrial defibrillators.

Post-stroke inflammatory response: effects of stroke evolution and outcome

Recovery after stroke is often hindered by further neurologic deterioration, which can affect up to 45% of patients. It has been suggested that one of the major causes of this neurologic deterioration may be post-ischemic cerebral inflammation. This review presents the basis of pathophysiologic mechanisms of post-stroke inflammation and discusses possible targets and routes for therapeutic intervention.

Aspirin in the prophylaxis of coronary artery disease

Aspirin has been used for more than 100 years, but its mechanisms of action have only been understood in the past 20 years. Aspirin interferes with arachidonic acid metabolism in platelets and endothelial cells and thereby reduces thromboxane A2 and prostacyclin. It also has other mechanisms of action, including anti-inflammatory roles, protection from oxidative stress, enhancement of fibrinolysis, and suppression of plasma coagulation and platelet-dependent inhibition of thrombin generation. It has been used for primary and secondary prevention of myocardial ischemia, and for primary and secondary prevention of cerebrovascular ischemia. We review the 5 pivotal studies relating to primary prevention for cardiovascular risk and the many studies relating to secondary prevention of myocardial ischemia. We also review the utility of aspirin in primary prevention of myocardial infarction and stroke. We conclude that aspirin is one of the most potent drugs ever discovered and that its effects extend well beyond those of cycloxoxygenase enzyme inhibition. Aspirin treatment does not preclude control of underlying and comorbid conditions such as diabetes mellitus, hypertension, and dyslipidemia. For most patients, a daily dose of 325 mg is optimal. Patients must understand the potential for gastrointestinal upset and hemorrhagic complications. The utility of aspirin is greater in coronary artery disease prevention than in cerebrovascular prevention.

Antiplatelet therapy in secondary stroke prevention

This article focuses on recent data about the safety and effectiveness of antiplatelet therapies for secondary stroke prevention. Highlights include a discussion of changes in the professional labeling for aspirin and the results of a low- versus high-dose aspirin trial (Aspirin after Carotid Endarterectomy trial). Safety issues regarding aspirin also are considered. Other topics include a review of recent data on thrombotic thrombocytopenic purpura (TTP) associated with ticlopidine and a brief update on clopidogrel. A summary of discussions related to the European Stroke Prevention Study 2 data and Food and Drug Administration consideration of combination dipyridamole/aspirin therapy are presented.