High-dose acetylsalicylic acid after cerebral infarction. A Swedish Cooperative Study

Pyrazolopyridine derivative acts as a novel cyclooxygenase inhibitor: antiplatelet effect in aged patients with ischemic stroke

OBJECTIVE

To examine the antiplatelet effect of a novel pyrazolopyridine derivative (KC-764) in geriatric patients with ischemic stroke.

DESIGN

Randomized clinical trial of three graded dose levels.

SETTING

A geriatric clinic attached to a nursing home.

PATIENTS

Fifteen patients with a history of cerebral infarction with a mean age of 75 +/- 5 years (range, 65-83). Patients were divided into three groups and administered 10, 20, or 40 mg/day KC-764 for 8 weeks.

MEASUREMENTS

Platelet aggregation induced by arachidonate, ADP, collagen and platelet-activating factor. Plasma or serum levels of thromboxane B2 and 6-ketoprostaglandin F1 alpha.

MAIN RESULTS

Platelet aggregation was inhibited by KC-764 administration and returned to the control level after discontinuation. Although plasma thromboxane B2 levels were markedly decreased, plasma 6-ketoprostaglandin F1 alpha was not affected. However, the dose of 10 mg/day was not sufficient to maintain an effective plasma level of KC-764. There were no side effects or changes in laboratory findings.

CONCLUSIONS

We confirmed that KC-764 at a dose of 20 to 40 mg/day is an effective antiplatelet agent and a good candidate for a trial to see if it is feasible for long-term use for the prevention of ischemic stroke in high-risk patients.

Failure of aspirin treatment after stroke

BACKGROUND AND PURPOSE

Despite its low efficacy, aspirin is the most widely used drug for secondary stroke prevention. The reasons why stroke recurs while patients are on aspirin are unknown. We have analyzed a series of patients who had recurrent strokes while on aspirin.

METHODS

Out of 2231 consecutive patients who were admitted to the Tel Aviv Medical Center from May 1988 through December 1992 with the diagnosis of ischemic stroke, 129 admissions were due to recurrent ischemic strokes while the patients were already on aspirin, and these were defined as aspirin failures. The clinical characteristics of those patients in whom aspirin treatment failed were compared with three control groups, each comprising 129 patients who had had only a single ischemic stroke and were then taking aspirin. One control group was matched for aspirin dose and date of first stroke; another control group was matched for age, sex, and date of first stroke; and a third control group was matched for age, sex, date of first stroke, and aspirin dose. Statistical analysis was carried out by two-tailed Student's t test and chi 2 test.

RESULTS

The average period until stroke was longer for patients on higher aspirin doses. Patients matched for aspirin dose and date of first stroke did not differ significantly in age (72.4 years in aspirin failures versus 74.2 years in the first control group) and sex (89 versus 94 men, respectively). Matching for age, sex, and date of first stroke but not for aspirin dose demonstrated a trend toward high frequency of aspirin failure in patients taking lower doses of aspirin (chi 2 test for trend = 3.5; P = .06). Comparison of aspirin-failure patients with a control group matched for age, sex, date of first ischemic stroke, and aspirin dose demonstrated that these patients more commonly had statistically significant hyperlipidemia (odds ratio, 2.6; 95% confidence interval, 1.0 to 6.8; P = .04) and ischemic heart disease (odds ratio, 2.3; 95% confidence interval, 1.3 to 3.9; P = .002).

CONCLUSIONS

We conclude that age and sex do not influence the efficacy of aspirin. Lower aspirin dose in patients with stroke recurrence suggests that aspirin doses of 500 mg daily or more should be used in secondary stroke prevention. Hyperlipidemia and ischemic heart disease are risk factors for stroke recurrence despite aspirin treatment, which requires further clinical and laboratory evaluation.

Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration

OBJECTIVE

To determine the effects of "prolonged" antiplatelet therapy (that is, given for one month or more) on "vascular events" (non-fatal myocardial infarctions, non-fatal strokes, or vascular deaths) in various categories of patients.

DESIGN

Overviews of 145 randomised trials of "prolonged" antiplatelet therapy versus control and 29 randomised comparisons between such antiplatelet regimens.

SETTING

Randomised trials that could have been available by March 1990.

SUBJECTS

Trials of antiplatelet therapy versus control included about 70,000 "high risk" patients (that is, with some vascular disease or other condition implying an increased risk of occlusive vascular disease) and 30,000 "low risk" subjects from the general population. Direct comparisons of different antiplatelet regimens involved about 10,000 high risk patients.

RESULTS

In each of four main high risk categories of patients antiplatelet therapy was definitely protective. The percentages of patients suffering a vascular event among those allocated antiplatelet therapy versus appropriately adjusted control percentages (and mean scheduled treatment durations and net absolute benefits) were: (a) among about 20,000 patients with acute myocardial infarction, 10% antiplatelet therapy v 14% control (one month benefit about 40 vascular events avoided per 1000 patients treated (2P < 0.00001)); (b) among about 20,000 patients with a past history of myocardial infarction, 13% antiplatelet therapy v 17% control (two year benefit about 40/1000 (2P < 0.00001)); (c) among about 10,000 patients with a past history of stroke or transient ischaemic attack, 18% antiplatelet therapy v 22% control (three year benefit about 40/1000 (2P < 0.00001)); (d) among about 20,000 patients with some other relevant medical history (unstable angina, stable angina, vascular surgery, angioplasty, atrial fibrillation, valvular disease, peripheral vascular disease, etc), 9% v 14% in 4000 patients with unstable angina (six month benefit about 50/1000 (2P < 0.00001)) and 6% v 8% in 16,000 other high risk patients (one year benefit about 20/1000 (2P < 0.00001)). Reductions in vascular events were about one quarter in each of these four main categories and were separately statistically significant in middle age and old age, in men and women, in hypertensive and normotensive patients, and in diabetic and nondiabetic patients. Taking all high risk patients together showed reductions of about one third in non-fatal myocardial infarction, about one third in non-fatal stroke, and about one third in vascular death (each 2P < 0.00001). There was no evidence that non-vascular deaths were increased, so in each of the four main high risk categories overall mortality was significantly reduced. The most widely tested antiplatelet regimen was "medium dose" (75-325 mg/day) aspirin. Doses throughout this range seemed similarly effective (although in an acute emergency it might be prudent to use an initial dose of 160-325 mg rather than about 75 mg). There was no appreciable evidence that either a higher aspirin dose or any other antiplatelet regimen was more effective than medium dose aspirin in preventing vascular events. The optimal duration of treatment for patients with a past history of myocardial infarction, stroke, or transient ischaemic attack could not be determined directly because most trials lasted only one, two, or three years (average about two years). Nevertheless, there was significant (2P < 0.0001) further benefit between the end of year 1 and the end of year 3, suggesting that longer treatment might well be more effective. Among low risk recipients of "primary prevention" a significant reduction of one third in non-fatal myocardial infarction was, however, accompanied by a non-significant increase in stroke. Furthermore, the absolute reduction in vascular events was much smaller than for high risk patients despite a much longer treatment period (4.4% antiplatelet therapy v 4.8% control; five year

The prevention of cardiovascular disease. Emphasis on secondary prevention

Atherosclerosis is a progressive disease affecting all major arteries. Clinical evidence of atherosclerosis increases the risk of subsequent morbid and mortal events fivefold to sevenfold over the next 5 to 10 years. The same risk factors contribute to the initial development of CVD events as to their recurrence. Both coronary and noncoronary events, such as stroke or PAD, reflect the severity of the underlying atherosclerotic process and strongly predict future excess CVD morbidity and mortality. Short-term and long-term survival depends on modifying the risk factors that contribute to CVD events. Although absolute proof of benefit for secondary prevention does not exist for all risk factors, the data from primary prevention trials and the secondary prevention trials that have been done argue strongly for aggressive intervention. Benefit has been demonstrated for smoking cessation, cholesterol reduction, and blood pressure control. Selected patients may benefit from additional medical, procedural, or surgical interventions to prolong life, such as beta-blocking agents, aspirin, or carotid endarterectomy. Many secondary prevention measures are a cost-effective way to reduce the substantial morbidity and mortality due to CVD. Contrary to primary prevention, even modest treatment effects from secondary prevention efforts can benefit large numbers of patients. Finally, secondary prevention may be more successful because patients with clinical evidence of CVD may be more highly motivated than their healthy counterparts to make and maintain lifestyle changes.

Platelet aggregation inhibitors in neurology

This literature review reports on secondary prevention of ischaemic stroke. The aim of secondary prevention is to protect patients who belong to a risk group from the occurrence of brain infarction. Symptomatic patients with a demonstrated carotid artery stenosis of 70% and more will most probably benefit from carotid endarterectomy if performed by a skilled surgeon in the absence of contraindications. Oral anticoagulant drugs play a minor role in the medical prevention of brain infarction. Antiplatelet drugs, however, have been in use for almost two decades and (meta-)analysis of clinical trials points to acetylsalicylic acid as a drug with a modest but certain contribution of about 15% in the endpoint reduction, even at lower dosages. The addition of dipyridamole to classic acetylsalicylic acid dose appears to increase the endpoint reduction to 30%. Neither dipyridamole nor sulfinpyrazone as monotherapy have been demonstrated to be efficacious in the secondary prevention of ischaemic stroke. Ticlopidine seems a promising alternative for acetylsalicylic acid in those patients who suffer adverse effects from acetylsalicylic acid. Ticlopidine itself, however, has a number of side-effects that limit its application. New clinical trials are under way in order to improve the efficacy of drug treatment in the secondary prevention of brain infarction.

Antiplatelet therapy in the treatment of cerebrovascular disease

Aspirin and the new agent ticlopidine have been the most thoroughly evaluated of the platelet-antiaggregating drugs used for the prevention of stroke and other vascular events. Numerous trials have shown aspirin to be effective in reducing the risk of myocardial infarction (MI), recurrent transient ischemic attacks, stroke, and vascular death in men at high risk for these events. Primary prevention trials have shown that aspirin reduces the risk of MI in healthy men over 50 years of age but does not reduce the risk of stroke. Two large, multicenter trials have shown that ticlopidine is effective in reducing the risk of fatal and nonfatal stroke in both men and women. Ticlopidine may also be effective in reducing the risk of recurrent stroke in patients who have had a completed thromboembolic stroke.

Two-year follow-up of aspirin responder and aspirin non responder. A pilot-study including 180 post-stroke patients

Aspirin is proposed to be effective in stroke-prophylaxis because it completely inhibits the platelet prostanoid-pathway. In about 90% of stroke victims, increased platelet reactivity (PR) can be reduced to the normal range by aspirin. Twelve hours later, about one third of them show an enhanced PR again. These patients are called secondary aspirin non responders (SANR). In this study the potential pathogenetic and prognostic impact of this biological feature on stroke recurrence was evaluated. Before discharge from the hospital, PR was determined 12 hours after an oral administration of 500 mg aspirin in 180 patients aged 58 +/- 15 years; 74 were female and 106 male. All had suffered a stroke in the internal carotid artery territory. Patients were treated with 3 x 500 mg aspirin/d and were followed up over a 24-month period. Major endpoints of this study were stroke, myocardial infarction or vascular death. On discharge from the hospital, 120 of the 180 patients showed a normal PR under aspirin treatment. High test values were found in 60 patients (SANR). Six patients were lost for follow-up. Because of side effects 36 (20%) of the 180 patients enrolled discontinued medication. Major endpoints occurred in 4 of these 36 patients (11%) and in 25 of the 138 remaining patients (18.1%); 19 patients died in consequence of a vascular event during the observation period. Major endpoints were seen in only 5 of 114 (4.4%) of the aspirin responders, but in 24 out of 60 SANR (40%, p < 0.0001). It may be assumed that early identification of SANR's is a clinically useful tool to classify patients at high risk for recurrence of vascular events.

Overview of trends in management and prognosis of stroke

Prevention is the ideal treatment for stroke, and the major decline in stroke mortality is most likely related to treatment of risk factors. Even when a vascular insult to the brain has occurred, an important treatment effect is the prevention of additional future events. No specific therapy for asymptomatic lesions has yet been proved to be effective. For patients with transient ischemia or mild stroke with functional recovery, the risk of additional strokes and death can be decreased by platelet-antiaggregating agents and carotid endarterectomy, which is effective in patients with greater than 70% stenosis of a symptomatic artery. Once a major stroke has occurred, the goals of therapy include prevention of disease progression, minimization of the permanent damage by the lesion, and prevention of new events. In addition to preventive therapies, several acute intervention therapies may be effective in reducing morbidity and mortality following stroke. While there are many similarities in cardiovascular and cerebrovascular disease, important differences appear to exist.

Can recurrent stenosis after carotid endarterectomy be prevented by low-dose acetylsalicylic acid? A double-blind, randomised and placebo-controlled study

Recurrent stenosis (> 50%) after carotid endarterectomy is reported with a frequency ranging from 7-20%. 232 patients undergoing carotid endarterectomy were randomised to low-dose acetylsalicylic acid (ASA, 75 mg daily) or placebo (identical tablets). The treatment was started the day before surgery and continued for 6 months. All patients were followed clinically for 1 year. Doppler examination was performed preoperatively (n = 230) and postoperatively (n = 228) and at follow-up at 2 (n = 220) and at 6 months (n = 174) after surgery. The degree of stenosis was estimated from the maximum Doppler frequency shift in the internal carotid artery. Recurrent stenosis of 30% or more was detected in 85 of the 220 patients (38.6%) at 2 months, and at 6 months in 73 of the 174 examined patients (42.0%). Stenosis > 50% was seen in 16 patients (9.2%) and occlusion was found in four patients (1.8%) at 6 months. No difference between the low-dose ASA-treated group (n = 112) compared to the placebo group (n = 108) was seen regarding recurrent stenosis. Women had an increased risk of recurrent stenosis (p < 0.001), whereas other factors such as age, hyperlipidaemia, diabetes and smoking were not associated with increased risk. Importantly, the number of neurological events did not differ between those with or without restenosis. Therefore, the indications for surgery of asymptomatic recurrent stenosis are questionable. The progress of arteriosclerosis in the contralateral carotid artery did not differ between the treatment groups.

The gastrointestinal toxicity of aspirin: an overview of randomised controlled trials

The proven benefit of aspirin in the secondary prevention of cardiovascular disease and its possible value in primary prevention must be weighted against its potential hazards. This paper is an overview of the gastrointestinal toxicity of aspirin, its most serious complication after intracerebral haemorrhage. Information on toxicity has been drawn only from randomised trials, thus avoiding the potential biases of observational studies. All randomised placebo controlled trials listed in the Anti-platelet Trialists Collaboration where a direct aspirin-placebo comparison was possible were included. Twenty-one trials were included, all but one of secondary prevention. There were over 75,000 person years of aspirin exposure. The pooled odds ratios for categories of gastrointestinal bleeding (e.g. haematemesis, melaena) were between 1.5-2.0; fatal bleeds were very rare. The risk of peptic ulcers was 1.3 and of upper gastrointestinal symptoms 1.7. These risks were lower than those found in observational studies. Attributable disease rates are also presented. For haematemesis for example they varied from 0.2-1.0 per 1000 person years. Toxicity was dose related. Aspirin does have significant gastrointestinal toxicity, although this is rarely fatal. More recent work has demonstrated the efficacy of low doses of aspirin (75 mg daily) but there is limited information yet available on its toxicity.

Aspirin response and failure in cerebral infarction

BACKGROUND AND PURPOSE

The purpose of this study was to assess the biological effect of aspirin as measured by the inhibition of platelet aggregation in patients taking aspirin for stroke prevention and in patients with acute stroke.

METHODS

We administered increasing doses of aspirin (325, 650, 975, and 1,300 mg daily) to 113 patients for stroke prevention and measured the inhibition of platelet aggregation in these patients and in 33 patients with acute stroke taking aspirin before stroke onset.

RESULTS

Eighty-five patients on < or = 325 and six on > or = 650 mg aspirin had complete inhibition of platelet aggregation. Increase of the dose by 325 mg in nine of the 22 patients with partial inhibition of platelet aggregation produced complete inhibition in five patients at 650 mg and in one at 975 mg. At 1,300 mg, three patients still had only partial inhibition of platelet aggregation (aspirin resistance). Of the 33 inpatients with acute stroke, 24 had platelet aggregation studies done before further administration of aspirin. Of these, 19 had complete inhibition of platelet aggregation and three had partial inhibition, with production of complete inhibition of platelet aggregation at dose escalation; one patient was aspirin-resistant and the other noncompliant.

CONCLUSIONS

How the inhibition of platelet aggregation relates to stroke prevention remains unclear. The ability of aspirin and the dose required to inhibit platelet aggregation may depend upon the individual.

Diabetes and stroke

Diabetes is a major risk factor for development of ischemic cerebrovascular disease. Patients with diabetes are at least two times more likely to have a stroke than nondiabetics. In addition, they are more likely to suffer increased morbidity and mortality after stroke. The mechanism of production of stroke secondary to diabetes may be due to cerebrovascular atherosclerosis, cardiac embolism, or rheologic abnormalities. The evaluation of cerebrovascular disease in diabetic patients is similar to the nondiabetic patient, with particular attention paid to adequate hydration prior to the administration of contrast agents. Treatment options for stroke in diabetics requires individualization but should include risk factor modification, and may include platelet antiaggregants, anticoagulation, or, in a well-defined subgroup, carotid endarterectomy.

Ticlopidine versus aspirin for the prevention of recurrent stroke. Analysis of patients with minor stroke from the Ticlopidine Aspirin Stroke Study

BACKGROUND AND PURPOSE

Ticlopidine has not been formally compared with aspirin in patients with a completed stroke. We therefore performed an analysis on a subgroup of patients from the Ticlopidine Aspirin Stroke Study (TASS) with a recent minor completed stroke as the qualifying ischemic event.

METHODS

This was a multicenter, double-blind, randomized trial of patients with a recent history of cerebral ischemia. Eligible patients had a qualifying minor stroke within 3 months of study entry. All patients received either 650 mg aspirin twice daily or 250 mg ticlopidine twice daily for up to 5.8 years. The primary study end point was the first occurrence of nonfatal stroke or death from any cause. A secondary end point was the first occurrence of a fatal or nonfatal stroke.

RESULTS

Minor stroke was the qualifying ischemic event in 927 patients (463 received ticlopidine and 464 received aspirin). The cumulative event rate at 1 year for nonfatal stroke or death was 6.3% for patients receiving ticlopidine and 10.8% for patients receiving aspirin, a 42% risk reduction in favor of ticlopidine. For fatal or nonfatal stroke, the cumulative event rate at 1 year was 4.8% for patients receiving ticlopidine and 7.5% for those receiving aspirin, a risk reduction of 36% for ticlopidine relative to aspirin. The overall risk reductions were 22.1% for nonfatal stroke or death and 19.9% for fatal or nonfatal stroke. Adverse reactions were reported in 58% of the ticlopidine patients and 51% of the aspirin patients.

CONCLUSIONS

The results in this subgroup are consistent with the overall TASS results and show that ticlopidine is somewhat more effective than aspirin for reducing the risk of stroke in patients with a completed minor stroke.

Role of ticlopidine for prevention of stroke

BACKGROUND

Ticlopidine, an antiplatelet agent with a unique mechanism of action, is now available for clinical use in the United States and Canada.

SUMMARY OF COMMENT

Recently two large randomized trials demonstrated that ticlopidine can reduce the risk of subsequent stroke in patients presenting with a transient ischemic attack or stroke. One study found that ticlopidine was more effective than aspirin for stroke prevention; however, it was less well tolerated than aspirin and was associated with severe but reversible neutropenia in almost 1% of patients.

CONCLUSIONS

Ticlopidine is effective for both primary and secondary stroke prevention. It has a favorable risk/benefit ratio and is a particularly attractive option for patients who are unable to take aspirin.

Evaluation of the clinical utility of platelet aggregation studies in the long-term follow-up of patients with atherosclerotic vascular disease

The present study was designed to evaluate the usefulness of laboratory monitoring of antiplatelet therapy by means of a multiparametric evaluation of in vitro platelet aggregation tests in the attempt to individually optimize a given therapeutic regimen. The presence of a condition of hyperaggregability was shown in approximately 80% of patients with different forms of atherosclerotic vascular disease not undergoing any therapeutic regimen with antiplatelet agents. Conversely, a significant decrease in platelet activity was observed in patients undergoing different therapies based on acetylsalicylic acid (ASA), ticlopidine, or indobufen. The similar antiaggregatory effect of low-dose vs. high-dose ASA therapies was also shown. Dipyridamole alone showed no antiaggregatory effect, which, in turn, was reached only by the addition of ASA. Nevertheless, the association of ASA plus dipyridamole did not show any stronger antiplatelet effect than ASA alone. The evaluation of in vitro platelet activity in a group of patients treated with picotamide failed to show any significant change in comparison with the untreated group, probably due to the short half-life of picotamide in man and/or to its capability of reversibly antagonizing the action of thromboxane at receptor level. The evaluation of a long-term follow-up of 90 patients treated with different antiplatelet agents supports the idea that a multiparametric analysis of in vitro platelet aggregation may provide valuable help in monitoring and optimizing a given therapeutic regimen.

Therapy in cerebrovascular disease: current status and future directions

OBJECTIVE

To assess the current status and future directions of therapy in cerebrovascular disease.

DATA SOURCES

English language literature search using MEDLINE, Index Medicus, reviews, texts and relevant papers.

STUDY SELECTION

Information has been drawn from approximately 200 articles.

DATA EXTRACTION AND SYNTHESIS

Those articles with most relevance to current practice and future directions in the therapy of cerebrovascular disease have been cited.

CONCLUSIONS

Much progress has been made over the last 30 years in the therapy of primary and secondary prevention of cerebrovascular disease. The introduction of antihypertensive agents has been largely responsible for the decline in mortality from stroke and, in some areas, the incidence. Anticoagulants such as warfarin protect against ischaemic stroke in patients with mitral or aortic valve disease and/or atrial fibrillation. Antiplatelet agents are clearly effective in the secondary prevention of ischaemic stroke after transient ischaemic attacks; the risk of stroke or death is reduced, on average, by 22%. In patients with subarachnoid haemorrhage, ischaemic complications caused by vasospasm are reduced by calcium channel blockers. A new wave of therapies is now on the horizon to minimise tissue damage in the early stages of ischaemic stroke ("tissue rescue") with the introduction of thrombolytic agents, calcium channel blockers, NMDA antagonists and haemodilution techniques and many of these are currently being subjected to clinical trial. If they prove to be effective, our current management of acute ischaemic stroke may alter dramatically.

Effects of acetylsalicylic acid in stroke patients. Evidence of nonresponders in a subpopulation of treated patients

Platelet reactivity (PR) was tested two and 12 hours after acetylsalicylic acid (ASA) intake in 82 stroke patients, aged 59 +/- 14 years (33 female and 49 male). 10% of these patients showed a pathologically enhanced PR at least two hours after intake of 500 mg ASA (= primary ASA-nonresponder (PNR)). Only 10 hours later, a further 26% of these ASA treated patients exhibited a pathological platelet reactivity (greater than 1.25) (= secondary ASA-nonresponder (SNR)). Single ASA dosages of 500 mg or 200 mg were of identical effectiveness. Additional administration of metoclopramide in combination with 100 mg ASA was more effective as compared to a single dosage of 1000 mg ASA. Those who were SNR at onset of ASA therapy remained SNR as well 28 days later. The change from a normal, ASA corrected PR, to pathological PR values before a period of 12 hours ended seemed a sudden and irreversible event that could only be corrected by the next ASA application.

The European Stroke Prevention Study (ESPS): results by arterial distribution

The European Stroke Prevention Study was a multicenter study comparing the effect of the combination of dipyridamole, 75 mg, and acetylsalicylic acid, 330 mg, three times a day, to that of placebo in 2,500 patients in the secondary prevention of stroke or death after one or more transient ischemic attacks, reversible ischemic neurological deficits, or strokes of atherothrombotic origin. The patients with vertebrobasilar events at entry comprised one-third of the whole patient population. The overall total incidence of stroke or death (the end points) during the 2-year follow-up in the placebo group was lower in the vertebrobasilar group compared to the carotid group (14% versus 24%, respectively). The combination therapy of dipyridamole and acetylsalicylic acid caused a marked reduction in the incidence of stroke or death in patients with vertebrobasilar (51%) and carotid (30%) events. When only stroke was considered as the end point, dipyridamole and acetylsalicylic acid seemed to be more effective in reducing the risk of transient ischemic attacks than stroke, and more effective in men than in women.

Efficacy of ticlopidine in the prevention of thromboembolic events in patients with VVI pacemakers

This study was designed to evaluate whether long-term treatment with ticlopidine reduces the incidence of thromboembolic episodes in patients with a VVI pacemaker. One hundred eleven patients with a VVI pacemaker were randomly assigned to two groups: group A (52 patients) was treated with ticlopidine at the dose of 250 mg a day; and group B (59 patients) was not treated and served as a control group. The primary analysis of efficacy of ticlopidine was based on the occurrence of thromboembolic episodes and of cardiovascular and cerebrovascular deaths. The mean follow-up period was 66 months. In group A, there was a significant reduction in the incidence of thromboembolic episodes (P less than 0.05) with a smaller incidence of total cardiovascular and cerebrovascular deaths (8 in group A and 18 in group B; P = 0.05) as compared with group B. Twelve percent of patients had moderate side effects with 1 dropout (epistaxis). Our data confirm the high incidence of thromboembolic events in patients with a VVI pacemaker and demonstrate the efficacy of ticlopidine in preventing them.

European Stroke Prevention Study. ESPS Group

We compared the outcomes of 2,500 patients who suffered from previous cerebrovascular disorders (transient ischemic attacks, reversible ischemic neurologic deficits, or completed strokes) treated with acetylsalicylic acid plus dipyridamole or matched placebo and followed for 2 years. Treatment was associated with a 33.5% reduction (p less than 0.001) in the incidence of all end points (deaths from all causes or strokes) by intention-to-treat analysis and a 36.5% reduction (p less than 0.001) by explanatory analysis. End point reduction appeared to be similar in men and women. The effect of treatment was similar regardless of the patients' age, nature of the qualifying cerebrovascular event, site of the responsible lesion, and diastolic blood pressure. Our results demonstrate the efficacy of combined therapy, but the efficacy of acetylsalicylic acid or dipyridamole alone and the most effective acetylsalicylic acid dosage remain in question.

Antithrombotic treatment of cerebrovascular disease

The most common type of cerebrovascular disease is ischaemia or infarction from atherothrombosis or cardiac embolism. Antithrombotic treatment with an antiplatelet agent or anticoagulant assumes a prior clinical classification into categories of transient ischaemic attack (TIA) or minor stroke, acute partial stable stroke, stroke-in-progression, and completed stroke. Aspirin reduces the risk of stroke, myocardial infarction, and death after TIA or minor stroke secondary to atherothrombosis. Aspirin is effective in both sexes at a dose of 300 or 1200 mg/day. Ticlopidine (500 mg/day), a new antiplatelet agent, is more effective than aspirin in preventing stroke and death in patients with TIA or minor stroke. Ticlopidine (500 mg/day) is effective in preventing recurrent stroke, myocardial infarction, or vascular death in patients with completed stroke. Aspirin has not been directly shown to be effective after completed stroke. No clear evidence exists for the use of anticoagulants in atherothrombotic cerebral vascular disease in patients presenting with TIA or minor stroke, acute partial stable stroke, stroke-in-progression, or completed stroke. Anticoagulation for rheumatic valvular heart disease is effective in preventing recurrent embolism. Long-term anticoagulation of patients with mechanical prosthetic valves protects against initial embolism and prevents recurrent embolism. The addition of aspirin (500-1000 mg/day) to warfarin reduces the rate of cerebral embolism from mechanical prosthetic heart valves but is associated with increased bleeding. The addition of dipyridamole (400 mg/day) to warfarin may be more effective than aspirin in reducing the rate of cerebral embolism from mechanical prosthetic heart valves and has fewer bleeding side-effects. Anticoagulation during the hospital phase of myocardial infarction reduces the incidence of systemic embolism/stroke. Long-term anticoagulation of patients after the hospital phase of myocardial infarction reduces the incidence of systemic embolism/stroke, recurrent myocardial infarction and death. Prophylactic anticoagulant treatment of patients with non-valvular atrial fibrillation reduces the incidence of embolism, but the optimal duration of treatment is not known. Immediate anticoagulation of patients with completed cardioembolic stroke is safe and effective in preventing recurrent embolism.

Indobufen in secondary prevention of transient ischaemic attack. Multicentre Ischaemic Attack Study Group

The secondary prevention of transient ischaemic attacks was assessed in 270 patients treated orally with 100 mg indobufen given twice daily for 12 months. After 1 month's treatment, the average number and average incidence of transient ischaemic attacks were reduced significantly (P less than 0.001) and remained suppressed throughout the treatment period. Treatment was interrupted in 17 patients: in two because of side-effects (gastric disturbances); in 10 because of fatal events (six completed strokes, two myocardial infarcts and two unrelated deaths); and in five due to poor protocol compliance. Progression to reversible ischaemic neurological deficit occurred in five patients. Most side-effects were mild and transient, mainly occurring in the first month of treatment. Overall, indobufen was judged to have good efficacy and safety by both patients and physicians.

Prognostic significance of fibrinopeptide A in survivors of cerebral infarction

We measured levels of fibrinopeptide A, beta-thromboglobulin, and fibrinogen in the plasma of 27 patients 2 months after their first stroke. Concentrations of fibrinopeptide A, a sensitive index of in vivo hypercoagulability, were significantly higher in the 18 ischemic stroke patients than in 40 age- and sex-matched controls and in the six patients who experienced recurrence within 5 years than in the 12 who remained asymptomatic. On the contrary, fibrinopeptide A levels had no prognostic significance among the nine patients with hemorrhagic stroke. Concentrations of beta-thromboglobulin, an index of platelet activation, were higher in the 27 stroke patients than in the 40 controls, but this index was not associated with stroke recurrence. Fibrinogen levels were not significantly higher in stroke patients than in controls. In a multivariate regression analysis of hemostatic and clinical variables, only fibrinopeptide A levels of greater than 4 ng/ml were significantly related to cerebral infarction. Our results support the role of hypercoagulability in the recurrence of ischemic stroke and may allow identification of subjects at high risk for it. If confirmed in more patients, our results could provide a rationale for clinical trials of anticoagulant therapy in such patients.

Platelet inhibitor agents in cardiovascular disease: an update

Platelets interact with the coagulation and fibrinolytic systems in the maintenance of hemostasis. However, these physiologic mechanisms may become pathologic, requiring prevention and treatment. In this review, the following clinical developments are analyzed: 1) the role of platelets in thrombogenesis; 2) the pharmacology of platelet inhibitory agents; and, most important, 3) the results of recent randomized trials of platelet inhibitor agents in different cardiovascular disorders. Aspirin reduces mortality and infarction rates in unstable angina and significantly decreases vascular mortality in acute myocardial infarction. Platelet inhibitors decrease mortality and recurrent cardiovascular events in the chronic phase after myocardial infarction. They also decrease vein graft occlusion rates after coronary bypass surgery. Although platelet inhibitors are beneficial in preventing acute vessel occlusion during coronary angioplasty, they are ineffective in preventing chronic restenosis. Antiplatelet agents, combined with warfarin, reduce thromboembolic events in patients with a mechanical prosthesis. Platelet inhibitors are also effective in secondary prevention of vascular events in patients with cerebrovascular disease. Finally, the use of aspirin for primary prevention of cardiovascular disease is still evolving, particularly in individuals at high risk. In conclusion, platelet inhibitors are effective in patients with a variety of cardiovascular disorders. The best studied, most inexpensive and least toxic agent is aspirin at a daily dose of 160 to 325 mg. Studies using new platelet inhibitor agents with different mechanisms of action are currently underway.