Danish very-low-dose aspirin after carotid endarterectomy trial

Antithrombotic therapies in aortic and peripheral arterial diseases in 2021: a consensus document from the ESC working group on aorta and peripheral vascular diseases, the ESC working group on thrombosis, and the ESC working group on cardiovascular pharmacotherapy

The aim of this collaborative document is to provide an update for clinicians on best antithrombotic strategies in patients with aortic and/or peripheral arterial diseases. Antithrombotic therapy is a pillar of optimal medical treatment for these patients at very high cardiovascular risk. While the number of trials on antithrombotic therapies in patients with aortic or peripheral arterial diseases is substantially smaller than for those with coronary artery disease, recent evidence deserves to be incorporated into clinical practice. In the absence of specific indications for chronic oral anticoagulation due to concomitant cardiovascular disease, a single antiplatelet agent is the basis for long-term antithrombotic treatment in patients with aortic or peripheral arterial diseases. Its association with another antiplatelet agent or low-dose anticoagulants will be discussed, based on patient's ischaemic and bleeding risk as well therapeutic paths (e.g. endovascular therapy). This consensus document aims to provide a guidance for antithrombotic therapy according to arterial disease localizations and clinical presentation. However, it cannot substitute multidisciplinary team discussions, which are particularly important in patients with uncertain ischaemic/bleeding balance. Importantly, since this balance evolves over time in an individual patient, a regular reassessment of the antithrombotic therapy is of paramount importance.

Aspirin in the Prevention of Cardiovascular Disease and Cancer

More than a century after its synthesis, daily aspirin, given at a low dose, is a milestone treatment for the secondary prevention of cardiovascular disease (CVD). Its role in primary prevention of CVD is still debated. Older randomized controlled trials showed that aspirin reduced the low incidence of myocardial infarction but correspondingly increased the low incidence of serious gastrointestinal bleeds without altering mortality. More recent trials see the benefit attenuated, perhaps obscured by other cardioprotective practices, while the bleeding risk remains, especially in older patients. Indirect evidence, both preclinical and clinical, suggests that aspirin may protect against sporadic colorectal cancer and perhaps other cancers. However, further studies are still necessary to warrant the consumption of aspirin for primary prevention of CVD and cancer by apparently healthy individuals.

Antithrombotic therapy in peripheral artery disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline focuses on antithrombotic drug therapies for primary and secondary prevention of cardiovascular disease as well as for the relief of lower-extremity symptoms and critical ischemia in persons with peripheral arterial disease (PAD).

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

The most important of our 20 recommendations are as follows. In patients aged ≥ 50 years with asymptomatic PAD or asymptomatic carotid stenosis, we suggest aspirin (75-100 mg/d) over no therapy (Grade 2B) for the primary prevention of cardiovascular events. For secondary prevention of cardiovascular disease in patients with symptomatic PAD (including patients before and after peripheral arterial bypass surgery or percutaneous transluminal angioplasty), we recommend long-term aspirin (75-100 mg/d) or clopidogrel (75 mg/d) (Grade 1A). We recommend against the use of warfarin plus aspirin in patients with symptomatic PAD (Grade 1B). For patients undergoing peripheral artery percutaneous transluminal angioplasty with stenting, we suggest single rather than dual antiplatelet therapy (Grade 2C). For patients with refractory claudication despite exercise therapy and smoking cessation, we suggest addition of cilostazol (100 mg bid) to aspirin (75-100 mg/d) or clopidogrel (75 mg/d) (Grade 2C). In patients with critical limb ischemia and rest pain unable to undergo revascularization, we suggest the use of prostanoids (Grade 2C). In patients with acute limb ischemia due to acute thrombosis or embolism, we recommend surgery over peripheral arterial thrombolysis (Grade 1B).

CONCLUSIONS

Recommendations continue to favor single antiplatelet therapy for primary and secondary prevention of cardiovascular events in most patients with asymptomatic PAD, symptomatic PAD, and asymptomatic carotid stenosis. Additional therapies for relief of limb symptoms should be considered only after exercise therapy, smoking cessation, and evaluation for peripheral artery revascularization.

A critical review of aspirin in the secondary prevention of noncardioembolic ischaemic stroke

Both secondary prevention (such as lifestyle modifications, pharmacotherapy or surgery) and an understanding of the influence of risk factors (including the different aetiologic mechanisms of cerebral ischaemia) play a pivotal role in reducing the burden of recurrent stroke. Regarding the types of preventative treatments available, variations exist across all clinical studies, including differences in target populations (including the type of cerebral ischaemia), risk factors, length of follow-up, drop-out rates and outcomes, which makes translating the results of clinical trials to individual patients difficult. However, with such limitations in mind, this critical albeit nonsystematic review, which compared aspirin with other antiplatelets and in combination with other drugs, showed that the benefit from aspirin treatment is consistently shown in ischaemic stroke, while harms are limited. Furthermore, no definite superiority is apparent across different antiplatelet therapies. Dual antiplatelet regimens may expose to a slight but measurable higher risk of haemorrhagic complications, perhaps in selective groups of patients (i.e. those with severe small-vessel disease or in selective racial groups). Based on our analysis, the indication of aspirin as the first-line choice, also recommended by several acknowledged international or national guidelines, may be confirmed. However, the complex nature of patients at risk of recurrent ischaemic stroke necessitates a comprehensive approach, which should be driven by the primary care physician, whose role is central to successful actions for secondary stroke prevention.

Aspirin dosing for the prevention and treatment of ischemic stroke: an indication-specific review of the literature

OBJECTIVE

To evaluate the efficacy of aspirin for the treatment and prevention of ischemic stroke and identify the minimum dose proven to be effective for each indication.

DATA SOURCES

PubMed and MEDLINE searches (up to January 2010) were performed to identify primary literature, using search terms including aspirin, stroke prevention, acute ischemic stroke, acetylsalicylic acid, atrial fibrillation, myocardial infarction, and carotid endarterectomy. Additionally, reference citations from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Articles published in English were evaluated and relevant primary literature evaluating the efficacy of aspirin in the prevention of stroke was included in this review.

DATA SYNTHESIS

Antiplatelet therapy is the benchmark for the prevention of ischemic stroke. Aspirin has been proven to prevent ischemic stroke in a variety of settings. Despite the frequency at which aspirin continues to be prescribed in patients at risk of ischemic stroke, there remains confusion in clinical practice as to what minimum dose is required in various at-risk patients. A thorough review of the primary literature suggests that low-dose (50-81 mg daily) aspirin is insufficient for some indications. Acute ischemic stroke treatment requires 160-325 mg, while atrial fibrillation and carotid arterial disease require daily doses of 325 and 81-325 mg, respectively.

CONCLUSIONS

Available evidence suggests that aspirin dosing must be individualized according to indication. Recommendations provided by national guidelines at times recommend lower doses of aspirin than have been proven effective. Higher doses are indicated for stroke prevention in atrial fibrillation (325 mg) and acute ischemic stroke patients (160-325 mg). Aspirin has not yet been proven effective for primary prevention of strokes in men, and a minimum dose for these patients cannot be determined from the available data.

Low-dose aspirin in patients with stable cardiovascular disease: a meta-analysis

OBJECTIVE

Many recommendations for aspirin in stable cardiovascular disease are based on analyses of all antiplatelet therapies at all dosages and in both stable and unstable patients. Our objective was to evaluate the benefit and risk of low-dose aspirin (50-325 mg/d) in patients with stable cardiovascular disease.

METHODS

Secondary prevention trials of low-dose aspirin in patients with stable cardiovascular disease were identified by searches of the MEDLINE database from 1966 to 2006. Six randomized trials were identified that enrolled patients with a prior myocardial infarction (MI) (n=1), stable angina (n=1), or stroke/transient ischemic attack (n=4). A random effects model was used to combine results from individual trials.

RESULTS

Six studies randomized 9853 patients. Aspirin therapy was associated with a significant 21% reduction in the risk of cardiovascular events (nonfatal MI, nonfatal stroke, and cardiovascular death) (95% confidence interval [CI], 0.72-0.88), 26% reduction in the risk of nonfatal MI (95% CI, 0.60-0.91), 25% reduction in the risk of stroke (95% CI, 0.65-0.87), and 13% reduction in the risk of all-cause mortality (95% CI, 0.76-0.98). Patients treated with aspirin were significantly more likely to experience severe bleeding (odds ratio 2.2, 95% CI, 1.4-3.4). Treatment of 1000 patients for an average of 33 months would prevent 33 cardiovascular events, 12 nonfatal MIs, 25 nonfatal strokes, and 14 deaths, and cause 9 major bleeding events. Among those with ischemic heart disease, aspirin was most effective at reducing the risk of nonfatal MI and all-cause mortality; however, among those with cerebrovascular disease, aspirin was most effective at reducing the risk of stroke.

CONCLUSION

In patients with stable cardiovascular disease, low-dose aspirin therapy reduces the incidence of adverse cardiovascular events and all-cause mortality, and increases the risk of severe bleeding.

SELECTIVE VERSUS ROUTINE INTRAOPERATIVE SHUNTING DURING CAROTID ENDARTERECTOMY

OBJECTIVE

The use of intraluminal shunting during carotid endarterectomy (CEA) remains controversial. Over the years, different shunting strategies have been used. More recently, the use of intraoperative electroencephalography and somatosensory evoked potential monitoring with selective intraluminal shunting has been explored. No studies have assessed the independent association of selective versus routine intraluminal shunting to outcomes after CEA.

METHODS

The clinical and radiological records of all patients undergoing CEA from 1994 to 2006 at an academic institution were reviewed retrospectively to assess outcomes at 72 hours. The independent association of selective intraluminal carotid artery shunting during CEA and perioperative stroke within 72 hours was assessed through multivariate logistic regression analysis.

RESULTS

In 1411 patients with both symptomatic and asymptomatic extracranial carotid artery disease, there were a total of 49 (3.5%) perioperative strokes after CEA. There were two (1%) cases of perioperative strokes among 194 patients in the selective shunting group compared with 47 out of 1217 (4%) in the routine shunting group (P = 0.04). Symptomatic carotid artery disease was associated with a twofold increase in the odds of experiencing perioperative stroke (odds ratio, 1.95; 95% confidence interval, 1.08–3.52; P = 0.03). Patients undergoing electrophysiological monitoring with selective intraluminal carotid artery shunting were more than seven times less likely to experience a perioperative stroke (odds ratio, 0.05; 95% confidence interval, 0.01–0.40; P < 0.01). Increasing cumulative surgical volume, particularly more than 200 total cases, was associated with more than a twofold decrease in perioperative stroke (odds ratio, 0.38; 95% confidence interval, 0.20–0.74; P < 0.01).

CONCLUSION

Regardless of symptomatic carotid artery disease or cumulative surgical volume, patients undergoing CEA with intraoperative electroencephalography and somatosensory evoked potential monitoring with selective intraluminal carotid artery shunting had a stroke rate lower than that of the routine shunting group. Selective shunting based on electroencephalography and somatosensory evoked potential monitoring may be superior to the nonselective strategy.

Hyperglycemia independently increases the risk of perioperative stroke, myocardial infarction, and death after carotid endarterectomy

OBJECTIVE

Clinical and experimental evidence suggests that hyperglycemia lowers the neuronal ischemic threshold, potentiates stroke volume in focal ischemia, and is associated with morbidity and mortality in the surgical critical care setting. It remains unknown whether hyperglycemia during carotid endarterectomy (CEA) predisposes patients to perioperative stroke and operative related morbidity and mortality.

METHODS

The clinical and radiological records of all patients undergoing CEA and operative day glucose measurement from 1994 to 2004 at an academic institution were reviewed and 30-day outcomes were assessed. The independent association of operative day glucose before CEA and perioperative morbidity and mortality were assessed via multivariate logistic regression analysis.

RESULTS

One thousand two hundred and one patients with a mean age of 72 +/- 10 years (748 men, 453 women) underwent CEA (676 asymptomatic, 525 symptomatic). Overall, stroke occurred in 46 (3.8%) patients, transient ischemic attack occurred in 19 (1.6%), myocardial infarction occurred in 19 (1.6%), and death occurred in 17 (1.4%). Increasing operative day glucose was independently associated with perioperative stroke or transient ischemic attack (Odds ratio [OR], 1.005; 95% confidence interval [CI], 1.00-1.01; P = 0.03), myocardial infarction (OR, 1.01; 95% CI, 1.004-1.016; P = 0.017), and death (OR, 1.007; 95% CI, 1.00-1.015; P = 0.04). Patients with operative day glucose greater than 200 mg/dl were 2.8-fold, 4.3-fold, and 3.3-fold more likely to experience perioperative stroke or transient ischemic attack (OR, 2.78; 95% CI, 1.37-5.67; P = 0.005), myocardial infarction (OR, 4.29; 95% CI, 1.28-14.4; P = 0.018), or death (OR, 3.29; 95% CI, 1.07-10.1; P = 0.037), respectively. Median and interquartile range length of hospitalization was greater for patients with operative day glucose greater than 200 mg/dl (4 d [interquartile range, 2-15 d] versus 3 d [interquartile range, 2-7 d]; P < 0.05).

CONCLUSION

Independent of previous cardiac disease, diabetes, or other comorbidities, hyperglycemia at the time of CEA was associated with an increased risk of perioperative stroke or transient ischemic attack, myocardial infarction, and death. Strict glucose control should be attempted before surgery to minimize the risk of morbidity and mortality after CEA.

Platelets in atherothrombosis

Atherosclerosis is a diffuse, systemic disease that affects the coronary, cerebral, and peripheral arterial trees. Disruption of atherosclerotic plaques leads to thrombus formation and arterial occlusion. This unpredictable and potentially life-threatening atherothrombotic sequence underlies clinical events such as angina, myocardial infarction, transient ischemic attacks, and stroke. One of the key components of a clot is the platelet. Although it was previously thought that platelets were relatively inactive cells that merely provided a framework for the attachment of other cells and proteins to mechanically stop bleeding due to injury, it is now known that this is not the case. Platelets secrete and express a large number of substances that are crucial mediators of both coagulation and inflammation. This article reviews the centrality of the platelet in atherothrombosis and briefly looks at the efficacy of antiplatelet agents in preventing and treating cardiovascular disease.

Secondary prevention of stroke with antiplatelet agents in patients with diabetes mellitus

The prevalence of diabetes mellitus (DM) varies from 1.2 to 13.3% in the general population. The most frequent is type 2 (non-insulin-dependent) DM, which constitutes 90-95% of all cases. DM increases the risk of cardiac disease, stroke, retinopathy, nephropathy, neuropathy and gangrene, and the disease is associated with an increased prevalence of other cardiovascular risk factors such as hypertension, hypercholesterolaemia, asymptomatic carotid artery disease, and obesity. The risk of stroke may be directly and indirectly increased by the presence of DM. Epidemiological data show that DM independently amplifies the risk of ischaemic stroke from 1.8- up to 6-fold, so that prevention of cardiovascular risk in diabetics is of utmost importance. The main goal is to control glycaemia, although it has never been shown to be beneficial in stroke patients. Other preventive strategies include antiplatelet treatment. The open-label Primary Prevention Project trial tested the efficacy of low-dose acetylsalicylic acid (ASA) in prevention of ischaemic events in high-risk patients, but failed to demonstrate a significant benefit of ASA in diabetic patients. However, in the CAPRIE trial, the benefit of clopidogrel was amplified in patients with DM versus those without DM in preventing ischaemic events. This difference was even more striking when comparing patients treated with insulin versus non-diabetics. Another trial -- MATCH -- tested the benefit of adding ASA to clopidogrel versus clopidogrel alone in the prevention of ischaemic events in high-risk cerebrovascular patients, two-thirds of whom had DM. Further research is needed to clarify the effects of different antiplatelet regimens in stroke prevention in diabetic patients, who should be considered as high vascular-risk patients.

Strategies in the high-risk cardiac patient undergoing non-cardiac surgery

The risk of perioperative myocardial infarction or cardiac death in patients undergoing non-cardiac surgery may be estimated by clinical risk factor analysis and by myocardial stress testing. While stress testing modalities accurately delineate reversible myocardial ischaemia, their positive predictive value is low, and it is not clear whether their implementation improves outcome when compared to risk stratification alone. Similarly, it remains to be shown that preoperative coronary revascularization is an effective strategy in reducing perioperative risk. Recent reports indicate that surgery undertaken in the first weeks after percutaneous coronary interventions may be associated with a significantly increased rate of major complications. Administration of beta-blockers and alpha2-adrenergic agonists to high-risk patients reduces surgical morbidity and mortality, and the benefits observed with beta-blockers may extend long after the operative period. In high-risk patients undergoing major surgery, pulmonary artery catheter-guided haemodynamic optimization has not been associated with better outcomes, whereas use of regional anesthetic techniques decreases the incidence of postoperative pulmonary, but not cardiac, complications.

Antithrombotic Therapy in Peripheral Arterial Occlusive Disease

This chapter about antithrombotic therapy for peripheral arterial occlusive disease is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004;126:179S-187S). Among the key recommendations in this chapter are the following: For patients with chronic limb ischemia, we recommend lifelong aspirin therapy in comparison to no antiplatelet therapy in patients with clinically manifest coronary or cerebrovascular disease (Grade 1A) and in those without clinically manifest coronary or cerebrovascular disease (Grade 1C+). We recommend clopidogrel over no antiplatelet therapy (Grade 1C+) but suggest that aspirin be used instead of clopidogrel (Grade 2A). For patients with disabling intermittent claudication who do not respond to conservative measures and who are not candidates for surgical or catheter-based intervention, we suggest cilostazol (Grade 2A). We suggest that clinicians not use cilostazol in patients with less-disabling claudication (Grade 2A). In these patients, we recommend against the use of pentoxifylline (Grade 1B). We suggest clinicians not use prostaglandins (Grade 2B). In patients with intermittent claudication, we recommend against the use of anticoagulants (Grade 1A). In patients with acute arterial emboli or thrombosis, we recommend treatment with immediate systemic anticoagulation with unfractionated heparin (UFH) [Grade 1C]. We also recommend systemic anticoagulation with UFH followed by long-term vitamin K antagonist (VKA) in patients with embolism [Grade 1C]). For patients undergoing major vascular reconstructive procedures, we recommend UFH at the time of application of vascular cross-clamps (Grade 1A). In patients undergoing prosthetic infrainguinal bypass, we recommend aspirin (Grade 1A). In patients undergoing infrainguinal femoropopliteal or distal vein bypass, we suggest that clinicians do not routinely use a VKA (Grade 2A). For routine patients undergoing infrainguinal bypass without special risk factors for occlusion, we recommend against VKA plus aspirin (Grade 1A). For those at high risk of bypass occlusion and limb loss, we suggest VKA plus aspirin (Grade 2B). In patients undergoing carotid endarterectomy, we recommend aspirin preoperatively and continued indefinitely (Grade 1A). In nonoperative patients with asymptomatic or recurrent carotid stenosis, we recommend lifelong aspirin (Grade 1C+). For all patients undergoing extremity balloon angioplasty, we recommend long-term aspirin (Grade 1C+).

Aspirin for the prevention of cardiovascular events in the elderly

Aspirin (acetylsalicylic acid), the most widely used antiplatelet drug, is clinically effective for the prevention of vascular ischaemic events. Very few primary or secondary prevention trials address the benefit-risk ratio of aspirin in the elderly. In secondary prevention, it is generally accepted that the beneficial effect of aspirin in the general patient population, demonstrated by randomised controlled trials, can be extrapolated to the elderly. Elderly patients are at relatively high risk for the development of vascular disease and might also be expected to derive substantial benefit from regular aspirin administration. However, there is no consensus about the definition of elderly and no specific prospective trial conducted in elderly subjects is available. Retrospective studies in the elderly found that the benefit provided by aspirin in older patients was similar or increased compared with younger individuals. In primary prevention, the potential benefit of antiplatelet agents must be balanced against the risk of bleeding, which is higher in older patients. The risk-benefit trade-off from the use of low-dose aspirin in the elderly is not yet established and caution should be exercised when using aspirin in primary prevention. In conclusion, aspirin should only be given for primary and secondary prevention in the elderly after a comprehensive evaluation of an individual patient's thrombotic and haemorrhagic risk has been conducted.

Antiplatelet therapy for preventing stroke and other vascular events after carotid endarterectomy

BACKGROUND

Antiplatelet drugs are effective and safe in a wide variety of patients at high risk of vascular ischaemic events. Among patients undergoing vascular surgical procedures, these agents significantly reduce the risk of graft or native vessel occlusion. In this context we wished to examine their effects in patients after carotid endarterectomy (CEA).

OBJECTIVES

The objective of this review was to evaluate whether antiplatelet agents are safe and beneficial after endarterectomy of the internal carotid artery.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched: 1 October 2002). In addition we performed comprehensive searches of the Cochrane Controlled Trials Register (Cochrane Library Issue 3, 2002), MEDLINE (January 1966 to September 2002) and EMBASE (January 1980 to September 2002), and checked all relevant papers for additional eligible studies.

SELECTION CRITERIA

We selected randomised, controlled, unconfounded trials comparing antiplatelet agents with control after carotid endarterectomy in symptomatic or asymptomatic carotid stenosis of different degrees. Treatment duration had to be at least 30 days after CEA. Follow-up should be at least three months.

DATA COLLECTION AND ANALYSIS

Two reviewers selected trials for inclusion, assessed trial quality, and extracted data independently from each other. From each trial we extracted, first the number of patients originally allocated to each treatment group, and, second the number of patients who met the criteria for each outcome (intention-to-treat analysis). We calculated a weighted estimate of the odds for each outcome event across studies using the Peto odds ratio method.

MAIN RESULTS

Six trials involving 907 patients were identified. For 'death (all causes)' the Peto odds ratio of 0.77 with a 95% confidence interval (CI) of 0.48-1.24 did not show a statistically significant difference between both treatment groups. For 'stroke (any)' the Peto odds ratio of 0.58 (95%CI: 0.34-0.98) indicated a statistically significant benefit in favour of antiplatelet drugs (p=0.04). Concerning the secondary outcome events 'vascular death', 'stroke or vascular death', 'serious vascular events', 'death or dependency', 'myocardial infarction', 'major extracranial haemorrhage', 'local haemorrhage requiring surgery', 'restenosis', 'TIA or amaurosis fugax', neither any benefit nor any hazard of antiplatelet drugs could be shown. For the outcome events 'intracranial haemorrhage', 'ischaemic stroke' and 'occurrence or progression of contralateral stenosis', data were either too sparse for meaningful analyses, or not available at all.

REVIEWER'S CONCLUSIONS

Our results may indicate that antiplatelet drugs did not significantly change the odds of 'death' but reduce the outcome 'stroke of any cause' in patients undergoing carotid endarterectomy. However, it can not be excluded that the beneficial effect in reducing stroke is due to chance. There is a suggestion that antiplatelets may increase the odds of haemorrhage, but there are currently too few data to quantify this effect.

Is aspirin "the weakest link" in cardiovascular prophylaxis? The surprising lack of evidence supporting the use of aspirin for cardiovascular disease

It is currently fashionable to prescribe aspirin, long-term to people with or at high risk of vascular events due to atherosclerosis. There is a moderately conclusive evidence for a short-term benefit after an acute vascular event. However, there is remarkably little evidence that long-term aspirin is effective for the prevention of vascular events and managing side effects may be expensive. Reductions in nonfatal vascular events may reflect an ability of aspirin to alter cosmetically the presentation of disease without exerting real benefit. Cardiovascular medicine appears prone to fads and fashions that are poorly substantiated by evidence. The current fashion for prescribing aspirin is reminiscent of the now discredited practice of widespread prescription of class I anti-arrhythmic drugs for ventricular ectopics. We should learn from experience.

Economic assessment of the secondary prevention of ischaemic events with lysine acetylsalicylate

OBJECTIVE

To analyse the economic benefits, in comparison with placebo, of the secondary prevention of ischaemic stroke and myocardial infarction (MI) with lysine acetylsalicylate (Kardégic) in patients with a history of ischaemic stroke, MI or stable and unstable angina pectoris.

DESIGN AND SETTING

This was a modelling study from the perspectives of direct medical costs, the social security system and society in France.

METHODS

Efficacy data for the secondary prevention of ischaemic events were derived from the Antiplatelet Trialists' Collaboration meta-analysis on antithrombotics. The rates and costs of ischaemic disease and of serious gastrointestinal adverse affects arising from long term aspirin treatment, as well as the costs of treatment with lysine acetylsalicylate, were taken from published sources, using French data where possible.

RESULTS

From the social security perspective, the estimated cost-effectiveness ratios show that the prevention of MI in patients with a history of unstable angina (with a 1-year follow-up) is a cost-saving strategy, with net benefits ranging from $US5703 (1996 prices) per avoided MI for lysine acetylsalicylate 300 mg/day to $US5761 per avoided MI for lysine acetylsalicylate 75 mg/day. The prevention of MI and stroke is also a cost-saving strategy in patients with prior MI [net benefits in a 2-year follow-up (5% discount rate) ranging from $US15 to $US494 per avoided MI and from $US37 to $US1170 per avoided stroke]. This was also true in patients with prior ischaemic stroke (net benefits in a 3-year follow-up ranging from $US610 to $US2082 per avoided MI and from $US176 to $US599 per avoided stroke). Finally, a 4-year follow-up in patients with a history of stable angina pectoris shows that prophylactic treatment with lysine acetylsalicylate is associated with net costs per avoided MI, ranging from $US4375 to $US3608 per avoided event. Sensitivity analysis confirmed that prophylaxis with lysine acetylsalicylate in patients at high risk of cardiovascular and cerebrovascular events results in savings in social security expenditure.

CONCLUSIONS

Our results underline the high economic benefit of using lysine acetylsalicylate to prevent secondary ischaemic stroke and MI in patients at high risk of cardiovascular and/or cerebrovascular events, leading to savings for the social security system and society.

Antiplatelet agents, carotid endarterectomy, and perioperative complications

Neurosurgeons are frequently involved in choosing an antiplatelet therapy for their patients in the perioperative period. New data obtained from the Aspirin and Carotid Endarterectomy (ACE) Trial suggest that low-dose aspirin is superior to high-dose aspirin therapy in reducing rates of perioperative stroke and death. The ACE-related data are reviewed, and the authors provide an update on current Food and Drug Administration-approved antiplatelet therapies for secondary stroke prevention, as well as a summary of antiplatelet therapies being developed.

Risk of primary intracerebral haemorrhage associated with aspirin and non-steroidal anti-inflammatory drugs: case-control study

OBJECTIVE

To examine the association between use of aspirin or other non-steroidal anti-inflammatory drugs and intracerebral haemorrhage.

DESIGN

Case-control study.

SETTING

13 major city hospitals in the Melbourne and metropolitan area.

SUBJECTS

331 consecutive cases of stroke verified by computed tomography or postmortem examination, and 331 age (+/- 5 years) and sex matched controls who were community based neighbours.

INTERVENTIONS

Questionnaire administered to all subjects either directly or by proxy with the next of kin. Drug use was validated by reviewing prescribing records held by the participants' doctors.

MAIN OUTCOME MEASURES

Previous use of aspirin or other non-steroidal anti-inflammatory drugs.

RESULTS

Univariate analysis showed no increased risk of intracerebral haemorrhage with low dose aspirin use in the preceding 2 weeks. Using multiple logistic regression to control for possible confounding factors, the odds ratio associated with the use of aspirin was 1.00 (95% confidence interval 0.60 to 1. 66, P=0.998) and the odds ratio associated with the use of other non-steroidal anti-inflammatory drugs was 0.85 (0.45 to 1.61, P=0. 611) compared with respective non-users in the preceding fortnight. Moderate to high doses of aspirin (>1225 mg/week spread over at least three doses) yielded an odds ratio of 3.05 (1.02 to 9.14, P=0. 047). There was no evidence of an increased risk among subgroups defined by age, sex, blood pressure status, alcohol intake, smoking, and the presence or absence of previous cardiovascular disease.

CONCLUSIONS

No increase in risk of intracerebral haemorrhage was found among aspirin users overall or among those who took low doses of the drug or other non-steroidal anti-inflammatory drugs. These data provide evidence that doses of aspirin usually used for prophylaxis against vascular disease produce no substantial increase in risk of intracerebral haemorrhage.

Early outcome in acute ischemic stroke is not influenced by the prophylactic use of low-dose aspirin

Aspirin reduces the occurrence of ischemic strokes. In some prophylactic trials it was suggested that aspirin might also lessen stroke severity, and hence improve outcome in patients sustaining an ischemic stroke. We examined stroke severity (by using the Mathew scale) and early outcome (Barthel index and mortality on day 21) in 91 patients with an acute (< 24 h) ischemic stroke in the territory of the middle cerebral artery. Twenty-seven patients were taking low-dose aspirin (100 or 200 mg/day) prior to their stroke, and 64 were not using antiplatelet drugs. There were no significant differences in baseline stroke severity, early (21 days) mortality or early disability between the two groups. The results of this small study suggest that the use of low-dose aspirin prior to an ischemic stroke does not influence the severity of that stroke and early outcome.

Variable influence of heparin and contrast agents on platelet function as assessed by the in vitro bleeding time

Both heparin and contrast agents have anticoagulant effects which are well-documented but their effects on platelets are not well-characterized. The purpose of the present study was to evaluate the sequential effects of heparin and then a contrast agent on platelet function during an angiographic procedure. Blood samples from 54 patients were obtained at baseline, after a 5000 unit bolus of heparin and after administration of a contrast agent (iohexol, n = 30: diatrizoate, n = 24) during angiography. The in vitro bleeding time (IVBT) was determined on nonanticoagulated whole blood using a hollow fiber device under physiological flow conditions. Mean IVBT at baseline was 3.6 +/- 2.7 minutes and increased to 17.0 +/- 12.3 minutes after heparin (p < 0.01). After heparin, 44.5% of the patients still had a normal IVBT (< 9.0 minutes), 11% of the patients had a moderately increased IVBT and the remaining patients had a large increase in their IVBT. When contrast was given (167 +/- 52 mls) following heparin, mean IVBT was higher in those who received diatrizoate (23.3 +/- 9.4 minutes) compared with iohexol (15.0 +/- 10.9 minutes, p < 0.05). However, 15 patients (28%) continued to have a normal IVBT after contrast and of these 80% had received iohexol.

Aspirin at any dose above 30 mg offers only modest protection after cerebral ischaemia

There is continuing debate about the relative efficacy of low (< 100 mg per day), medium (300 to 325 mg per day), and high (> 900 mg per day) doses of aspirin in patients after a transient ischaemic attack or non-disabling stroke. The purpose of this study was to resolve the issue. Thus a minimeta-analysis was performed on data from 10 randomised trials of aspirin only v control treatment in 6171 patients after a transient ischaemic attack or nondisabling stroke. The data on the trials were listed in an appendix of the report on the second cycle of the Antiplatelet Trialists' Collaboration. There was virtually no difference in relative risk reduction for low, medium, and high doses of aspirin (13%, 9%, and 14% respectively). This equivalence corresponds with the results of the UK-TIA trial in a direct comparison of 300 and 1200 mg. The Dutch TIA trial showed no difference in efficacy of 30 and 283 mg. It is concluded that aspirin at any dose above 30 mg daily prevents 13% (95% confidence interval 4-21) of vascular events and that there is a need for more efficacious drugs.

Drugs and surgery in the prevention of ischemic stroke

Randomized clinical trials have proved that warfarin therapy decreases the risk of stroke in patients with nonvalvular atrial fibrillation and in those who have had a myocardial infarction. In patients who are not candidates for long-term anticoagulant therapy, aspirin is beneficial, but the reduction in risk is smaller with aspirin than with warfarin. In patients with cerebral ischemic symptoms of noncardiac origin, aspirin and ticlopidine reduce the risk of stroke, but the benefit is modest. Given alone, neither dipyridamole nor sulfinpyrazone prevents stroke. The question remains whether either of these drugs plus aspirin is better than aspirin alone. The optimal dose of aspirin for stroke prevention has not been established. Carotid endarterectomy reduces the risk of stroke in symptomatic patients with at least 70 percent stenosis, as determined by arteriography. Current trials are addressing the question of whether endarterectomy is beneficial for patients with moderate degrees of carotid stenosis. The benefit of endarterectomy for patients with asymptomatic carotid lesions remains unclear.

Effect of low dose aspirin on augmented plasminogen activator inhibitor type 1 activity in patients with permanent pacemakers

To clarify the activity states of coagulation and fibrinolysis in patients with a permanent pacemaker, we studied 29 patients more than 4 months after operation. They were divided into a single pacemaker lead group (S, n = 14) and a double lead group (D, n = 15). Prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin III, tissue-type plasminogen activator (tPA) activity, plasminogen activator inhibitor type-1 (PAI-1) activity, and platelet aggregation were measured and compared to those in an age-matched control group (C, n = 7). The effects of low dose aspirin (81 mg/day) in the patients (n = 21) were also studied 2 weeks after administration. PAI-1 activity in groups S and D was significantly higher than that in the group C (53.5 +/- 36.5, 86.8 +/- 59.2 ng/mL vs 19.4 +/- 7.2 ng/mL; P < 0.01 and P < 0.005). Platelet aggregation induced by collagen was slightly higher in groups S and D than group C. Other parameters were not significantly different. In the patients, low dose aspirin significantly suppressed collagen induced platelet aggregation (71.8 +/- 20.3% vs 41.7 +/- 28.3%; P < 0.005), but not PAI-1 activity. tPA activity was increased significantly by the low dose aspirin administration (3.94 +/- 1.85 ng/mL vs 2.48 +/- 1.19 ng/mL; P < 0.005). Thus, PAI-1 activity in patients with a permanent pacemaker is elevated, and the activity is not suppressed by low dose aspirin unlike the platelet aggregation.