A randomized trial of aspirin and sulfinpyrazone in patients with TIA

Antithrombotic Therapy for Secondary Prevention in Patients with Non-Cardioembolic Stroke or Transient Ischemic Attack: A Systematic Review

Stroke embodies one of the leading causes of death and disability worldwide. We aimed to provide a comprehensive insight into the effectiveness and safety of antiplatelet agents and anticoagulants in the secondary prevention of ischemic stroke or transient ischemic attack. A systematic search for randomized controlled trials, comparing antiplatelet or anticoagulant therapy versus aspirin or placebo among patients with ischemic stroke or transient ischemic attack, was performed in order to summarize data regarding the different regimens. Keyword-based searches in the MEDLINE, EMBASE, and Cochrane Library databases were conducted until the 1st of January 2021. Our search explored 46 randomized controlled trials involving ten antiplatelet agents, six combinations with aspirin, and four anticoagulant therapies. The review of the literature reflects that antiplatelet therapy improves outcome in patients with ischemic stroke or transient ischemic attack. Monotherapy proved to be an effective and safe choice, especially in patients with a high risk of bleeding. Intensified antiplatelet regimens further improve stroke recurrence; however, bleeding rate increases while mortality remains unaffected. Supplementing the clinical judgment of stroke treatment, assessment of bleeding risk is warranted to identify patients with the highest benefit of treatment intensification.

Multidisciplinary treatment of posterior circulation ischemia

Compromise of blood flow to the brain leads to cerebral ischemia, which if left untreated may even result in cerebral infarction. This has been the main cause of major morbidity and mortality over the years in the US and around the world. Cerebral ischemia to the posterior fossa is more critical and difficult to treat. This is primarily due to complex anatomy and physiology of the posterior fossa cerebal circulation. There has been multiple modalities tested over the years to treat posterior fossa ischemia which have definitely contributed in the outcome in patients with this complex problem. Improving the blood flow in the areas of brain at risk in properly selected patients could prevent impending cerebral ischemia and infarction. Today, there are mainly three types of treatment offered to patients with posterior cerebral ischemia. These are (a) medical, (b) endovascular and (c) surgical. The recent advances in technology, the diagnosis and mode of therapy, has definitely improved the outcomes of cerebral ischemia. We discuss the multidisciplinary treatment of posterior circulation ischemia. Various pre-operative and operative techniques involved in treating patients with posterior cerebral ischemia are discussed.

Prophylaxis of climbers for prevention of embolic accidents

The development of deep venous thrombosis and the ensuing secondary complications of pulmonary embolism, disseminated intravascular coagulation, and stroke may be produced in high altitude climbers as a result of acclimatization to altitude. To prevent these serious disorders, investigation for predisposing risk factors and consideration of anticoagulative therapy should be considered.

Interactions of aspirin and salicylic acid with prednisolone for inhibition of lymphocyte proliferation

The anti-inflammatory properties of salicylates and prednisolone were investigated using inhibition of in vitro phytohemagglutinin-stimulated lymphocyte proliferation in human whole blood from healthy male and female subjects. Steroids and salicylates are used in conjunction for the treatment of inflammatory disorders such as rheumatoid arthritis and inhibit the proinflammatory transcription factor, NFKB, by different mechanisms. Data generated using various combinations of these drugs were analyzed using isobolograms and the universal surface response approach based on the Loewe additivity principle. The interaction between aspirin and prednisolone was mildly antagonistic while that between salicylic acid and prednisolone was modestly synergistic at therapeutic concentrations. Further, aspirin was slightly more potent in males, but the nature of the steroid-salicylate interaction was similar across genders. This study helps rationalize part of the beneficial effects of steroids and salicylates in treatment of inflammatory disorders.

Stroke is an emergency

Stroke is an emergency. Ischemic stroke is similar to myocardial infarction in that the pathogenesis is loss of blood supply to the tissue, which can result in irreversible damage if blood flow is not restored quickly. Public education is needed to emphasize the warning signs of stroke. Patients should seek medical help immediately, using emergency transport systems. Therapy geared toward minimizing the damage from an acute stroke should be started without delay in the emergency room. This includes measures to protect brain tissue, support perfusion pressure, and minimize cerebral edema. Strategies for improving recovery should also begin immediately. All major medical centers need stroke teams and stroke units. Stroke prevention should be given high priority as a public health strategy. Risk factor management should be part of general health care and should begin in childhood, with emphasis on nutrition, exercise, weight control, and avoidance of tobacco. Health screening and early treatment of hypertension and hypercholesterolemia has decreased the incidence of stroke and heart disease, but these efforts need to be expanded to reach all segments of the population. Basic research has opened the door to new therapies aimed at re-establishing blood flow and limiting tissue damage. Clinical trials have already led to changes in stroke prevention, including studies of carotid endarterectomy and ticlopidine and warfarin therapy (for patients with atrial fibrillation). Trials in progress are testing the usefulness of ancrod, neuroprotective agents, antioxidant agents, anti-inflammatory agents, low-molecular-weight heparin, thrombolytic drugs, and angioplasty. Any delay starting therapy after an acute stroke will result in progressive, irreversible loss of brain tissue. Clinicians should remember that for a stroke patient, time is brain tissue.

Effects of a thromboxane A2-receptor antagonist, a thromboxane synthetase inhibitor and aspirin on prostaglandin I2 production in endothelium-intact and -injured aorta of guinea pigs

We examined the effects of KW-3635, a thromboxane (TX) A2-receptor antagonist, and OKY-046, a TX synthetase inhibitor, on the prostaglandin (PG) I2 production in endothelium-intact and -injured guinea pig aorta and compared them with those of aspirin. In the endothelium-intact aorta, both the low (3 mg/kg) and the high (100 mg/kg) dose of aspirin similarly reduced the PGI2 production, as measured ex vivo 1 hr after the injury. In contrast, neither KW-3635 (10 mg/kg) nor OKY-046 (30 mg/kg) inhibited the PGI2 production. The endothelial injury, induced by balloon catheterization, caused a reduction of PGI2 production in the aorta and decline of plasma PGI2/TXA2 ratio. In the endothelium-injured animals, the high dose of aspirin further reduced the PGI2 production in the aorta, whereas KW-3635 and OKY-046 did not affect it. KW-3635 and OKY-046 also ameliorated the reduced ratio of PGI2/TXA2 in the plasma. The present results demonstrate that aspirin, but not KW-3635 or OKY-046, reduces the PGI2 production in the aorta either in the endothelium-intact or -injured state. It is thus suggested that the TXA2-receptor antagonist and the TX synthetase inhibitor have some advantages over aspirin when used for the prevention of acute thrombosis after percutaneous transluminal angioplasty.

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.

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

Ticlopidine hydrochloride: its current use in cerebrovascular disease

It is estimated that half a million Americans will suffer strokes this year (National Stroke Association, 1989). The physical, emotional, and financial impacts of such an event are enormous. While stroke treatment methods have improved and rehabilitation programs have expanded, a substantial number of stroke patients are left with major disabilities. The only way to intervene is to focus on stroke prevention through the identification and modification of risk factors. One such intervention involves antiplatelet therapy, which has been found to reduce the risk of initial thrombotic stroke and the potential for recurrent stroke. Nurses caring for stroke patients need to know about this type of therapy, because continuity of pharmacological treatment, patient compliance, and education are essential for adequate stroke prevention.

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.

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.

Stroke prevention in women: role of aspirin versus ticlopidine

Stroke is the third leading cause of death in North America. Most studies indicate that women are just as likely as men to have an initial stroke but less likely to have a recurrent stroke. Aspirin and ticlopidine are two antiplatelet drugs that reduce the risk of recurrent stroke by 25% to 30%. In some stroke prevention trials, aspirin has been shown to be more effective for men than for women. In contrast, major stroke prevention trials using ticlopidine have demonstrated equal benefit in women and in men. The overall incidence of adverse effects seen with ticlopidine is not significantly different from that observed with aspirin. There are now two effective agents useful in stroke prevention in both men and women.

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.

A randomized trial comparing ticlopidine hydrochloride with aspirin for the prevention of stroke in high-risk patients. Ticlopidine Aspirin Stroke Study Group

We report the results of the Ticlopidine Aspirin Stroke Study, a blinded trial at 56 North American centers that compared the effects of ticlopidine hydrochloride (500 mg daily) with those of aspirin (1300 mg daily) on the risk of stroke or death. The medications were randomly assigned to 3069 patients with recent transient or mild persistent focal cerebral or retinal ischemia. Follow-up lasted for two to six years. The three-year event rate for nonfatal stroke or death from any cause was 17 percent for ticlopidine and 19 percent for aspirin--a 12 percent risk reduction (95 percent confidence interval, -2 to 26 percent) with ticlopidine (P = 0.048 for cumulative Kaplan-Meier estimates). The rates of fatal and nonfatal stroke at three years were 10 percent for ticlopidine and 13 percent for aspirin--a 21 percent risk reduction (95 percent confidence interval, 4 to 38 percent) with ticlopidine (P = 0.024 for cumulative Kaplan-Meier estimates). Ticlopidine was more effective than aspirin in both sexes. The adverse effects of aspirin included diarrhea (10 percent), rash (5.5 percent), peptic ulceration (3 percent), gastritis (2 percent), and gastrointestinal bleeding (1 percent). With ticlopidine, diarrhea (20 percent), skin rash (14 percent), and severe but reversible neutropenia (less than 1 percent) were noted. The mean increase in total cholesterol level was 9 percent with ticlopidine and 2 percent with aspirin (P less than 0.01). The ratios of high-density lipoprotein and low-density lipoprotein to total cholesterol were similar in both treatment groups. We conclude that ticlopidine was somewhat more effective than aspirin in preventing strokes in this population, although the risks of side effects were greater.

The Canadian American Ticlopidine Study (CATS) in thromboembolic stroke

The Canadian American Ticlopidine Study (CATS) is a randomised, double-blind, placebo-controlled trial to assess the effect of ticlopidine (250 mg twice daily) in reducing the rate of subsequent occurrence of stroke, myocardial infarction, or vascular death in patients who have had a recent thromboembolic stroke. Twenty-five centres entered 1072 patients into the study between 1 week and 4 months after their qualifying stroke. The patients were treated and followed for up to 3 years (mean 24 months). In the efficacy analysis, the event rate per year for stroke, myocardial infarction or vascular death, considered together, was 15.3% in the placebo group and 10.8% in the ticlopidine group, representing a relative risk reduction with ticlopidine of 30.2% (95% confidence interval 7.5-48.3%; p = 0.006). Ticlopidine was beneficial for both men and women (relative risk reductions 28.1%, p = 0.037, and 34.2%, p = 0.045, respectively). Analysis by intention-to-treat gave a smaller estimate of risk reduction (23.3%, p = 0.020) for stroke, myocardial infarction, or vascular death. Adverse experiences associated with ticlopidine included neutropenia (severe in about 1% of cases) and skin rash and diarrhoea (severe in 2% of cases each); all were reversible. This study provides evidence of a beneficial effect of ticlopidine in both men and women with a recent thromboembolic stroke.

Issues in planning and interpreting active control equivalence studies

Active control equivalence studies, with the goal of demonstrating therapeutic equivalence between a new and an active control treatment, are becoming more widespread due to current therapies that reflect previous successes in the development of new treatments. Because ethical requirements preclude the use of a placebo or no-treatment control for internal study validation, certain methodologic issues arise in active control equivalence trials that require special attention. We emphasize a special feature of this alternative study design, namely, its reliance on an implicit "historical control assumption". To conclude that a new drug is efficacious on the basis of an active control equivalence study (ACES) requires a fundamental assumption that the active control drug would have performed better than a placebo, had a placebo been used in the trial. In designing an ACES, one needs some assurance that historical estimates of the active control drug's efficacy relative to placebo are applicable to the new experimental setting. Steps that can be taken to compile such evidence and to justify the use of an active control equivalence design are described. These issues are illustrated in the context of a planned study to evaluate the efficacy of a new drug for the prevention of stroke, using aspirin as an active control.

Low-dose acetylsalicylic acid (ASA) plus dipyridamole versus dipyridamole alone in the prevention of stroke in patients with reversible ischemic attacks

A total of 243 patients who had reversible ischemic attacks (RIA) were submitted to clinical trial to determine whether dipyridamole (400 mg/day) (D) or aspirin (100 mg/48 hours) + dipyridamole (300 mg/day) (ASA + D) would produce significant reduction in the subsequent occurrence of RIA and completed stroke. One hundred and fifteen were selected for Group ASA + D and 71 were treated with dipyridamole only. The treatment groups were similar in relation to age, sex, risk factors, duration and presumed vascular territory of RIA, incidence of alterations of arterial supra-aortic trunks, cerebral infarct (CT scan), and platelet function. Patients were followed for a mean time of 21 months. At the end of the study, 21.7% of the ASA + D group and 19.7% in the D group had suffered new episodes of RIA or completed stroke (p = 0.88). Frequency of stroke (reversible ischemic neurologic deficit or completed stroke) was 7.8% in the ASA + D patients and 9.8% in the D patients (p = 0.83). Subgroup analysis did not show significant differences either. It is concluded that ASA + D has no significantly greater beneficial effect than that observed with D alone in the secondary prevention of atherothrombotic cerebral ischemia. However, a statistical Type II error cannot be excluded by the reduced number of recurrences.

Comparison of the effect of acetylsalicylic acid on platelet function in male and female patients with ischemic stroke

The aim of this study was to observe whether acetylsalicylic acid (ASA) had different effects in both sexes. Out of the ischemic stroke patients who were admitted to the National Taiwan University Hospital (NTUH), those who had not taken ASA or ASA-like drugs for more than 2 weeks were selected for this study. For the diagnosis of ischemic stroke, computed tomography (CT) of the brain was performed in all cases, and for differential diagnosis, other necessary procedures were employed in a few cases. The serum salicylate (SA) level was measured by Trinder's method, thromboxane B2 (TXB2) and 6-keto-PGF1 alpha by radioimmunoassay, threshold concentration of adenosine diphosphate (ADP) by Born's method, and circulating platelet aggregates (CPA) by Wu and Hoak's method. The present study showed that the means of serum SA levels after administration of the same dose of ASA were not significantly different between the two sexes. After ingestion of ASA, a single dose of 75 mg, 300 mg or 600 mg, or 300 mg 4 times a day, mean plasma TXB2 levels were significantly suppressed and mean threshold concentrations of ADP were significantly elevated in the two sexes. After administration of above-mentioned various doses of ASA, the abnormally high plasma TXB2 levels and abnormally low threshold concentrations of ADP and CPA ratios were significantly normalized in both male and female patients. Plasma 6-keto-PGF1 alpha levels were not influenced by ingestion of ASA 75 mg, but significantly depressed by administration of ASA 300 mg in both sexes. There were no sex differences in the antiplatelet effect of ASA in this experiment.

Thromboembolism and antithrombotic therapy in cerebrovascular disease

The use of antithrombotic therapy of any type assumes a thrombotic mechanism for the patient's brain ischemia. Typical, but by no means specific, clinical and radiologic features of atherothrombotic, lacunar and embolic brain ischemia are outlined. The indications for anticoagulant therapy include progressing stroke and cardiogenic brain embolus. According to previous randomized trials, transient ischemic attacks should be managed with aspirin, 1.0 to 1.5 g daily, pending the results of studies of smaller aspirin doses and other platelet-active drugs. In patients with a suspected cardiogenic brain embolus, anticoagulation should be withheld pending the results of a computed tomographic scan done 24 to 48 hours from onset. If there is no evidence of hemorrhagic transformation or a large area of infarction and the patient does not have sustained hypertension, heparin therapy should be initiated in an effort to prevent a recurrent embolus.

Anti-thrombotic effect of KC-404, a novel cerebral vasodilator

KC-404 prevented mice from death and rats from A-V block, both induced by rapid i.v. injection of adenosine diphosphate (ADP), at high doses (5-100 mg/kg, i.v.). KC-404, at relatively lower doses (0.5-2 mg/kg, i.v.), inhibited the electroencephalographic (EEG) change in rat rapidly administered with arachidonic acid (AA) into the internal carotid artery. KC-404 (0.3-3 mg/kg, p.o.) inhibited the necrotic change of lower leg, paw or finger of rat when injected with sodium laurate into the femoral artery. KC-404 at doses up to 100 mg/kg, p.o. did not alter bleeding time in rat. Thus, KC-404 is expected to be of therapeutic value in cerebrovascular disorders accompanying thrombus in cerebral vasculature.

Surgical reconstruction of the proximal vertebral artery

The authors have reviewed their experience in the management of 55 patients admitted to Henry Ford Hospital with symptoms of vertebrobasilar insufficiency and associated proximal vertebral artery stenosis or occlusion. In 48 patients, the symptoms occurred as multiple repeated events, five of which resulted in permanent deficits. The remaining seven patients had single events, four of which caused permanent deficit. These patients had been treated unsuccessfully with antiplatelet agents (37 cases) and with anticoagulant drugs (15 cases) before surgery. Most patients had multiple angiographic abnormalities, including bilateral vertebral stenosis in 19 cases, unilateral vertebral stenosis and contralateral occlusion in 18, unilateral vertebral hypoplasia and contralateral stenosis in 10, subclavian artery stenosis with steal in seven, and bilateral vertebral artery occlusion in one case. Posterior communicating arteries could not be demonstrated angiographically in 18 patients. Thirty-four patients had associated stenotic or occlusive lesions of the internal carotid artery. Forty-eight underwent a vertebral-to-carotid artery transposition. Of these, 18 had an associated carotid endarterectomy and seven had a vertebral artery endarterectomy immediately before the transposition. Two patients had saphenous vein grafts, one from the subclavian and one from the common carotid artery to the vertebral artery. Other surgical procedures included vertebral artery ligation in one case, transposition of the vertebral artery to the thyrocervical trunk in two cases and to the subclavian artery in one case, and endarterectomy of the origin of the vertebral artery in one case. All but two patients had complete resolution of their symptoms: one had persistent dizziness and the other had syncopal episodes. Complications included transient Horner's syndrome (30 cases) which became permanent in four cases, vocal cord paralysis (three cases), elevated hemidiaphragm without respiratory difficulty (two cases), and superficial would infection (one case). There were no deaths. Although the presentation of patients with vertebrobasilar insufficiency is generally characteristic, we believe that a specific diagnosis can be established only by angiographic means. Anticoagulants have been used to alleviate symptoms in some cases but are ineffective in solving the primary hemodynamic problem. Surgical reconstruction of the affected area deserves further evaluation in the management of these patients.