XIV. Cerebral ischemia: the role of thrombosis and of antithrombotic therapy. Study group on antithrombotic therapy

Intracranial Atherosclerotic Stenoses: Pathophysiology, Epidemiology, Risk Factors and Current Therapy Options

Intracranial atherosclerotic stenoses (ICAS) are one of the most common causes of first and recurrent cerebrovascular ischaemic events worldwide, with highest prevalence in Asian, Hispanic and African populations. Clinical trials have improved the understanding of epidemiology, risk factors and imaging characteristics of patients with ICAS. Current therapeutic approaches concerning these patients include management of risk factors, best medical therapy, potentially endovascular and rarely surgical therapy. In our review, we elucidate the current epidemiology and evidence in evaluation of risk factors and therapeutic options for providing favourable outcome for patients with ICAS.

Medical Treatment of Intracranial Atherosclerosis: An Update

For patients with symptomatic intracranial atherosclerosis (ICAS), antithrombotic agents are the mainstay of therapy. Anticoagulation (warfarin) is not widely used since it is not more effective than aspirin and carries a high risk of bleeding. New oral anticoagulants are showing promise, but their use has not been investigated in appropriate clinical trials. Since the recurrent stroke risk is high with aspirin monotherapy, dual antiplatelets are considered in the early stage of symptomatic ICAS. Based on the Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) and Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) results, aspirin plus clopidogrel has been recommended. However, this combination was not superior to aspirin monotherapy in patients with ICAS in the CHANCE substudy. Progression of ICAS is common, and it is associated with recurrent strokes. In the Trial of Cilostazol in Symptomatic Intracranial Arterial Stenosis (TOSS) study, aspirin plus cilostazol was more effective than aspirin monotherapy in preventing progression. The TOSS II trial showed that the overall change in stenosis was better with aspirin plus cilostazol than with aspirin plus clopidogrel. Aside from antithrombotic therapy, risk factor management is critical for secondary prevention, and high blood pressure is clearly linked to recurrent stroke. However, blood pressure may have to be cautiously managed in the early stage of stroke. Considering that ICAS is the major cause of stroke worldwide, further investigations are needed to establish optimal management strategies for patients with ICAS.

Stroke Prevention in Atrial Fibrillation and Valvular Heart Disease

There is a clinically staggering burden of disease stemming from cerebrovascular events, of which a majority are ischemic in nature and many are precipitated by atrial fibrillation (AF). AF can occur in isolation or in association with myocardial or structural heart disease. In the latter case, and when considering health at an international level, congenital and acquired valve-related diseases are frequent contributors to the current pandemic of AF and its clinical impact. Guidelines crafted by the American Heart Association, American College of Cardiology, European Society of Cardiology and Heart Rhythm Society underscore the use of vitamin K antagonists (VKAs) among patients with valvular heart disease, particularly in the presence of concomitant AF, to reduce the risk of ischemic stroke of cardioembolic origin; however, the non-VKAs, also referred to as direct, target-specific or new oral anticoagulants (NOACs), have not been actively studied in this particular population. In fact, each of the new agents is approved in patients with AF not caused by a valve problem. The aim of our review is to carefully examine the available evidence from pivotal phase 3 clinical trials of NOACs and determine how they might perform in patients with AF and concomitant valvular heart disease.

The effect of recombinant human growth hormone therapy in patients with completed stroke: a pilot trial

OBJECTIVE

To evaluate the safety and potential efficacy of "recombinant human growth hormone (rhGH)" on the functional recovery of completed stroke patients.

METHOD

Completed stroke patients were recruited. All participants were randomly assigned to the GH group (rhGH injection and rehabilitative therapy) or the control group (only rehabilitative therapy). Above all, they were closely monitored for safety. Further, for the efficacy measurement, Korean Modified Barthel Index (K-MBI), Manual Muscle strength Test (MMT), and Fugl-Meyer assessment (FMA) were assessed to determine the changes of functional recovery during 6-months of the study period. Along with it, diffusion tensor image was taken as the baseline, and a followed-up study to observe the changes in diffusion tensor tractography (DTT), during the period, and one patient in the GH group was also examined with functional MRI (fMRI). Index of fatigue on 5 point scale for the study period was also assessed.

RESULTS

Twenty-two patients were enrolled, and 15 completed the study and were included in the analysis. No harmful adverse events were observed in the GH group. By comparison between the groups, the GH group showed more improvement in K-MBI than the control group (p<0.05). DTT showed less decrement of fibers in the GH group than in the control group, without statistical significance. fMRI showed an increment in the activated area. Patients in the GH group expressed no fatigue at all, during the study period (p=0.00).

CONCLUSION

The administration of rhGH in long term resulted in the improvement in K-MBI, and subjectively less tiredness during the injection period.

The outcome of patients with transient ischemic attacks and stroke treated with anticoagulants

Long-term anticoagulant treatment was given to 25 patients with transient ischemic attacks (TIA) and 49 stroke patients with reversible ischemic neurological deficit or cerebral embolism. Another 16 TIA patients were observed without anticoagulant treatment. Life table analyses, comparing the observed with the expected frequency, revealed increased mortality in the TIA patients irrespective of whether or not they had received anticoagulants. The stroke patients treated with anticoagulants also had a higher mortality than expected. On the other hand, the incidence of subsequent stroke was not higher than expected in the TIA and stroke patients treated with anticoagulants, while it was significantly increased in the TIA patients not treated with anticoagulants. Thus, the risk of stroke, but not the risk of death, was normalized by the anticoagulant treatment. Unacceptably serious bleeding complications were seen in the group of stroke patients with anticoagulant treatment. Bleeding complications, in both TIA and stroke patients, seemed to be related to lengthy treatment, high blood pressure on admission or insufficient patient compliance.

Variation in ischemic stroke frequency in Japan by season and by other variables

BACKGROUND AND PURPOSE

It is unclear whether acute ischemic stroke exhibits a seasonal pattern in Japan. The aim of the present study was to elucidate seasonal differences in acute ischemic stroke.

METHODS

Our study enrolled 12,660 patients with ischemic stroke (7943 men, 4717 women; mean age, 70.1 years, S.D. 11.5; median 70; range 18-107). We divided the year into four parts: spring (March-May); summer (June-August); fall (September-November); and winter (December-February). Time of stroke onset was divided into three subgroups: daytime (08:00-16:00), evening (16:00-24:00), and night (24:00-08:00). We examined the association between clinical characteristics, season, and time of stroke onset.

RESULTS

Stroke occurred least frequently in spring (22.9%), followed by winter (25.3%), fall (25.8%), and summer (26.0%) (P<0.001). No differences in age, National Institutes of Health Stroke Scale (NIHSS) score, modified Rankin Scale (m-RS) score, history of stroke/transient ischemic attack (TIA), or risk factors for stroke were observed among the four seasons. Stroke in men (63.8% vs. 62.4%; P<0.01), lacunar stroke (LS) (41.2% vs. 39.4%, P<0.01), atherothrombotic stroke (ATS) (34.0% vs. 32.3%; P<0.01), and nighttime stroke (26.5% vs. 24.8%; P<0.05) were observed more frequently in summer compared to other seasons. This contrasts with the findings for stroke in women (39.0% vs. 36.7%; P<0.05), cardioembolic stroke (CES) (23.4% vs. 20.6%; P<0.05), and daytime stroke (47.4% vs. 45.0%; P<0.05), which were more frequent in winter.

CONCLUSIONS

Acute ischemic stroke displays seasonal characteristics according to gender, stroke subtype, and time of stroke onset. These results may have important clinical implications in ischemic stroke prevention.

Effect of cerebrocrast on the function of human platelets and release of the arachidonic acid from plasma membrane

Diabetes mellitus (DM) is accompanied by several cardiovascular complications such as coronary artery disease, atherosclerosis, hypertension, cerebral and myocardial infarction, etc. DM induces the alteration of platelet functions including activation, hyperaggregation, adhesiveness, and formation of thrombi. Release of AA from phospholipids of the PM, synthesis of TxA(2),PGE(2), activity of PLA(2), and PLC are increased in the platelets of the DM patients. Stimulation of PLA(2) activity and accumulation of bioactive metabolites such as AA, its oxygenated derivatives, prostaglandins and PAF can evoke glucose production, also. In this study we explored the effect of the 1,4-dihydropyridine compound cerebrocrast at a low concentration (10(-6)-10(-8)M) on the level of intracellular calcium in unstimulated human platelets and those stimulated with thrombin as well as release of [(3)H] AA from phospholipids of platelet PM. Cerebrocrast at a concentration of 10(-6) M decreased the basal level of intracellular calcium concentration (platelets were loaded with Fura-2) in unstimulated as well as in thrombin stimulated platelets. Cerebrocrast at concentrations of 10(-6), 10(-7), 10(-8) M inhibited release of [(3)H] AA from phospholipids of platelet PM. We conclude that blockade of human platelet activation with cerebrocrast can prevent aggregation, adhesion and formation of thrombi. The inhibition of [(3)H] AA release from phospholipids of platelet PM can prevent formation of eicosanoids such as TxA(2), PGG(2), and PGH(2) plus AA oxygenated derivatives. These effects of cerebrocrast are very significant in the treatment of DM-evoked cardiovascular complications.

Evidence-based treatment of patients with ischemic cerebrovascular disease

The results of trials that study patients with defined lesions (atrial fibrillation without valvular heart disease, various severities of carotid artery stenosis in the neck, intracranial artery stenosis) are very helpful for clinicians caring for patients with those conditions. On the other hand, trials that group all patients with brain ischemia together are not very helpful. Modern technology now makes it possible to define quickly and safely: (1) the location, nature, and severity of causative cerebrovascular, cardiac, and aortic lesions; (2) blood constituents and coagulability; and, (3) the presence, location, and severity of ischemic brain damage. As in all medicine, treatment should be aimed at the cause of disease, not the time course and severity of present damage. Clearly, more trials are needed in patients who have been studied thoroughly using modern technology. Until then, clinicians must understand the context of the trial data to determine if the results are applicable to Mr. or Ms. Jones, and the patients sitting before them in the office or in the hospital bed.

Antiplatelet effect of marchantinquinone, isolated from Reboulia hemisphaerica, in rabbit washed platelets

Platelet activation is involved in serious pathological situations, including atherosclerosis and restenosis. It is important to find efficient antiplatelet medicines to prevent fatal thrombous formation during the course of these diseases. Marchantinquinone, a natural compound isolated from Reboulia hemisphaerica, inhibited platelet aggregation and ATP release stimulated by thrombin (0.1 units mL(-1)), platelet-activating factor (PAF; 2 ng mL(-1)), collagen (10 microg mL(-1)), arachidonic acid (100 microM), or U46619 (1 microM) in rabbit washed platelets. The IC50 values of marchantinquinone on the inhibition of platelet aggregation induced by these five agonists were 62.0 +/- 9.0, 86.0 +/- 7.8, 13.6 +/- 4.7, 20.9 +/- 3.1 and 13.4 +/- 5.3 microM, respectively. Marchantinquinone inhibited thromboxane B2 (TxB2) formation induced by thrombin, PAF or collagen. However, marchantinquinone did not inhibit TxB2 formation induced by arachidonic acid, indicating that marchantinquinone did not affect the activity of cyclooxygenase and thromboxane synthase. Marchantinquinone did inhibit the rising intracellular Ca2+ concentration stimulated by the five platelet-aggregation inducers. The formation of inositol monophosphate induced by thrombin was inhibited by marchantinquinone. Platelet cAMP and cGMP levels were unchanged by marchantinquinone. The results indicate that marchantinquinone exerts antiplatelet effects by inhibiting phosphoinositide turnover.

Antithrombotic activities of green tea catechins and (-)-epigallocatechin gallate

The antithrombotic activities and mode of action of green tea catechins (GTC) and (-)-epigallocatechin gallate (EGCG), a major compound of GTC, were investigated. Effects of GTC and EGCG on the murine pulmonary thrombosis in vivo, human platelet aggregation in vitro, and ex vivo, and coagulation parameters were examined. GTC and EGCG prevented death caused by pulmonary thrombosis in mice in vivo in a dose-dependent manner. They significantly prolonged the mouse tail bleeding time of conscious mice. They inhibited adenosine diphosphate- and collagen-induced rat platelet aggregation ex vivo in a dose-dependent manner. GTC and EGCG inhibited ADP-, collagen-, epinephrine-, and calcium ionophore A23187-induced human platelet aggregation in vitro dose dependently. However, they did not change the coagulation parameters such as activated partial thromboplastin time, prothrombin time, and thrombin time using human citrated plasma. These results suggest that GTC and EGCG have the antithrombotic activities and the modes of antithrombotic action may be due to the antiplatelet activities, but not to anticoagulation activities.

Antithrombotic and thrombolytic therapy for ischemic stroke

Anthithrombotic therapy is widely used as primary and secondary preventative treatment for ischemic cerebrovascular disease. Aspirin modestly reduces the risk for subsequent ischemic stroke after a transient ischemic attack or initial stroke. Adding dipyridamole may enhance this benefit. Ticlopidine confers a small additional benefit, but with more side effects and cost. The best dose of aspirin remains unsettled, but recent studies support the concept of very early initiation of treatment. Intravenous and subcutaneous heparin or low-molecular-weight heparin is not recommended because of enhanced bleeding side effects, unless venous thrombosis in debilitated patients is a concern. Thrombolytic therapy with rt-PA was recently demonstrated to improve outcome in ischemic stroke patients treated within 3 hours of onset. However, the risk-benefit ratio is narrow because of the substantial risk for intracerebral hemorrhage with rt-PA. An enhanced ability to identify patients at risk for bleeding and newer thrombolytic drugs may expand the utility of this therapy, as would extending the time window beyond the current 3-hour period. Clinicians should anticipate continued advances in the fields of antithrombotic and thrombolytic therapy for ischemic stroke over the next few years.

Thrombosis and cerebrovascular disease

Strokes are heterogeneous not only with respect to their presentation, but more importantly in terms of the underlying pathology. There are now a number of choices available for the treatment of ischemic stroke, and the causative mechanisms responsible for each individual stroke must be considered in choosing an appropriate form of treatment. This article explores the underlying pathophysiological mechanisms responsible for the major categories of stroke and also examines the reasons why strokes worsen or evolve.

Genetic risk factors and ischaemic cerebrovascular disease: role of common variation of the genes encoding apolipoproteins and angiotensin-converting enzyme

DNA polymorphisms in genes encoding apolipoproteins (apo) A-I, C-III, B and E and angiotensin-converting enzyme (ACE) have been proposed to be associated with the risk of coronary artery disease (CAD). We studied whether the same genetic markers would also be associated with the occurrence and extent of atherosclerosis in cervical arteries. DNA samples from 234 survivors of stroke or a transient ischaemic attack aged 60 years or less were examined. The presence of atherosclerosis was assessed using aortic arch angiograms. The SstI polymorphism of apoA-I/C-III gene locus, the XbaI polymorphism of apoB gene, common apoE phenotypes and the insertion/deletion polymorphism of the ACE gene were analysed. The allele frequencies of the apoA-I/C-III, apoB, apoE or ACE gene did not differ between the groups with (n = 148) or without (n = 85) cervical atherosclerosis. However, when patients with at least one apoE4 allele and one X2 allele of apoB were combined and compared with those without either of them (E2E3 or E3E3 and X1X1), a significant association with the presence of cervical atherosclerosis was found (P = 0.03). The patients having the E2E3 phenotype had a significantly elevated serum triglyceride level compared with those with the E3E3 phenotype (P = 0.03). Serum high-density lipoprotein (HDL) cholesterol was lower in the patients with the E2E3 phenotype than in those with the E3E3 and E3E4 (P = 0.01 and P = 0.06, respectively). The apoB or ACE genotypes were not significantly associated with serum lipid or lipoprotein levels. There was no association between the ACE gene polymorphism and the occurrence of hypertension. In conclusion, the interaction of common apoB and apoE alleles may increase the risk of atherosclerosis in cervical arteries.

Effect of PP1D-1, a synthetic antiplatelet compound, on rabbit platelets

The antiplatelet mechanism of a synthetic compound, 2-chloro-3-methoxycarbonylpropionamido-1,4-naphthoquinone (PP1D-1), was studied by employing washed rabbit platelets in vitro. PP1D-1 concentration-dependently inhibited thrombin (0.1 U/ml)-, platelet-activating factor (2 ng/ml)-, collagen (10 microg/ml)-, arachidonic acid (100 microM)- and U46619 (1 microM)-induced aggregation and ATP release in washed rabbit platelets. The IC50 values of PP1D-1 for aggregation induced by the above inducers are 17.9+/-1.7, 9.8+/-1.1, 3.9+/-0.4, 1.8+/-0.3 and 1.7+/-0.3 microM, respectively. PP1D-1 did not affect platelet thromboxane B2 or prostaglandin D2 formation induced by arachidonic acid, indicating that it did not affect cyclooxygenase and thromboxane synthase activities. PP1D-1 significantly inhibited the formation of inositol 1,4,5-trisphosphate caused by these five platelet stimulators. Moreover, PP1D-1 inhibited the increase in intracellular calcium concentration induced by these agents. On the contrary, PP1D-1 did not inhibit thapsigargin-elevated intracellular calcium concentration in indomethacin-pretreated platelets, indicating it did not influence the effect of thapsigargin. According to these data, PP1D-1 exerts antiplatelet effects mainly by inhibiting phosphoinositide turnover.

Inhibitory effects of TA-993, a new 1,5-benzothiazepine derivative, on platelet aggregation

TA-993, an l-cis 4',8-dimethyl derivative of the Ca2+ antagonist diltiazem, and some of its metabolites inhibited platelet aggregation induced by collagen, ADP, epinephrine, platelet activating factor, arachidonic acid, and U-46619 in human platelets in vitro. Among the metabolites, MB3 was the most potent (IC50, <1 micromol/L; several hundred times more potent than the parent compound). The d isomer of MB3 was >100 times less potent than the l isomer. Unlike acetylsalicylic acid (ASA), TA-993 inhibited both primary and secondary phases of ADP-induced platelet aggregation and also exhibited a disaggregating effect on human platelet aggregates. The inhibitory effect of TA-993 was enhanced when used in combination with ASA. In ex vivo studies involving rats, TA-993 (approximately 0.3 to 100 mg/kg PO) dose-dependently inhibited collagen-induced platelet aggregation (ED50, 3 mg/kg PO). In the whole-blood platelet aggregation system in rats, orally administered TA-993 was also inhibitory in single (3 to 30 mg/kg) or repeated daily (10 mg/kg per day for 10 days) dosage. Orally administered TA-993 dose-dependently inhibited ADP-induced platelet aggregation ex vivo in dogs (0.3 to 10 mg/kg), significantly protected mice against collagen + epinephrine-induced thromboembolic death (10 mg/kg), and inhibited thrombus formation in an arteriovenous shunt in rats (30 mg/kg). The Ca2+-antagonistic action of TA-993 was very weak in depolarized canine basilar arteries: the potency was approximately 1/10 that of diltiazem (d-cis) and d-TA-993. These results suggest that antiplatelet action is more characteristic of the l-cis than the d-cis 1,5-benzothiazepine structure and that TA-993 may become a clinically useful antiplatelet agent of this structure series.

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.

Evidence for episodic platelet activation in acute ischemic stroke

BACKGROUND AND PURPOSE

Enhanced thromboxane biosynthesis has previously been reported in patients with acute ischemic stroke. In this study we examined the time course of thromboxane biosynthesis after the onset of symptoms in 13 patients with acute cerebral infarction.

METHODS

We obtained five to eight consecutive 6-hour urine samples from each of these 13 patients within the first 48 hours after onset of symptoms to study the dynamics of platelet activation in this setting. The urinary excretion of the major enzymatic metabolite of thromboxane B2, 11-dehydro-thromboxane B2, was measured by a previously validated radioimmunoassay. The excretion rate was compared with that of 20 control patients with nonvascular neurological diseases.

RESULTS

Eleven patients (85%) had at least one value exceeding 2 SD of the control mean (251 pmol/mmol creatinine). The proportion of samples with an elevated 11-dehydro-thromboxane B2 level was markedly similar in each of the eight 6-hour collection periods (mean, 52 +/- 8%; range, 40% to 67%). In 4 patients (31%) the excretion rate was elevated in all measurements obtained. In the 11 patients with enhanced thromboxane biosynthesis, no uniform pattern of changes over time in metabolite excretion emerged, with 3 patients having peak values at 0 to 12 hours, 3 at 12 to 24 hours, 3 at 24 to 36 hours, and 2 at 36 to 48 hours. The level and dynamics of 11-dehydro-thromboxane B2 excretion were related neither to the neurological symptoms nor to the type or site of the cerebral ischemia.

CONCLUSIONS

We conclude that episodes of platelet activation occur repeatedly during the first 48 hours after the onset of symptoms of an acute ischemic stroke. Given its apparent dynamic nature, this ongoing process may be amenable to pharmacologic modulation.

Cilostazol, a novel cyclic AMP phosphodiesterase inhibitor, prevents reocclusion after coronary arterial thrombolysis with recombinant tissue-type plasminogen activator

Inhibitors of cyclic nucleotide phosphodiesterase hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate are known to inhibit platelet aggregation, which plays an important role in acute reocclusion after thrombolysis in acute myocardial infarction. In the present study of a canine preparation of coronary artery thrombosis superimposed on high-grade stenosis, we tested whether the antithrombotic agent cilostazol, an inhibitor of cAMP phosphodiesterase, could prevent acute reocclusion or sustain coronary blood flow after thrombolysis when used with recombinant tissue-type plasminogen activator (rt-PA) and heparin. Intravenous infusion of rt-PA (0.5 mg/kg body wt for 30 minutes) and heparin (a 150 IU/kg body wt i.v. bolus and then 25 IU/kg body wt per hour i.v.) was combined with cilostazol (0.6 or 1.8 mg/kg body wt for 60 minutes). Without cilostazol, reperfusion was observed in seven of eight dogs, but reocclusion occurred in six of these seven dogs after 9 +/- 2 minutes. After administration of 1.8 mg/kg body wt cilostazol (group B-2; a 120-minute observation after the start of rt-PA infusion), reperfusion occurred in all seven dogs (p < 0.05 versus control group), and brief cyclic reocclusion was observed in only one dog 63 minutes after reperfusion. At the same dose of cilostazol (group B-2L; a 240-minute observation after the start of rt-PA infusion), reperfusion occurred in all five dogs (p < 0.05 versus control group), and coronary blood flow was well maintained except for one short reocclusion in one dog. Cilostazol inhibited cyclic flow reduction in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute revascularization for progressing stroke

The effectiveness of acute stage vascular reconstruction in cases of progressing stroke is reported. The clinical material consists of 28 cases of progressing stroke in the anterior circulation upon which vascular reconstruction was performed. Following admission, brain protective substances (500 ml mannitol, 500 mg vitamin E, 500 mg phenytoin) and dextran, were administered to the patients, and induced hypertension was also performed. Changes in symptoms were then observed and vascular reconstruction was carried out in cases where symptoms progressed. The vascular lesion was on the internal carotid artery in 8 cases and on the middle cerebral artery in 20 cases. Complete disappearance of neurological symptoms was obtained in 12 cases, whereas only mild neurological symptoms remained but a return to normal social life was possible in 11 other cases. Symptoms remained in three cases and there were two fatalities. In a long-term follow-up study, there were no cases of aggravation of symptoms due to ischaemic stroke. Moreover, the reconstruction was judged as effective on the basis of cerebral blood flow and metabolism. We concluded that acute vascular reconstruction for progressing stroke under the administration of brain protective substances is effective in preventing the progression of neurological symptoms.

Syst-Eur. A multicentre trial on the treatment of isolated systolic hypertension in the elderly: objectives, protocol, and organization

The Syst-Eur Trial is a concerted action of the European Community's Medical and Health Research Programme. The trial is carried out in consultation with the World Health Organization, the International Society of Hypertension, the European Society of Hypertension and the World Hypertension League. This article describes the objectives and the protocol of Syst-Eur, a multicentre trial designed by the European Working Party on High Blood Pressure in the Elderly (EWPHE), to test the hypothesis that antihypertensive treatment of elderly patients with isolated systolic hypertension results in a significant change in stroke morbidity and mortality. Secondary endpoints include cardiovascular events, such as myocardial infarction and congestive heart failure. To be eligible patients must be at least 60 years old and have a systolic blood pressure averaging 160-219 mmHg with a diastolic pressure less than 95 mmHg. Patients must give their informed consent and be free of major cardiovascular and non-cardiovascular diseases at entry. The patients are randomized to active treatment or placebo. Active treatment consists of nitrendipine (10-40 mg/day), combined with enalapril (5-20 mg/day) and hydrochlorothiazide (12.5-25 mg/day), as necessary. The patients of the control group receive matching placebos. The drugs (or matching placebos) are stepwise titrated and combined in order to reduce systolic blood pressure by 20 mmHg at least to a level below 150 mmHg. Morbidity and mortality are monitored to enable an intention-to-treat and per-protocol comparison of the outcome in the 2 treatment groups. A one-year pilot trial (1989) showed that the protocol is practicable. The Ethics Committee therefore decided to start the definite study (1990), in which randomized patients will be followed for 5 years. Recruitment of new centres and of the required 3,000 patients will last 3 years (until 1993).

Progressing cerebral infarction in relation to plasma glucose in gerbils

We studied neurologic morbidity and its evolution during hyperglycemia induced immediately after permanent unilateral common carotid artery ligation in Mongolian gerbils. A total of 60 animals were divided into five groups: one experiencing severe hyperglycemia for 1 hour after the onset of ischemia (brief hyperglycemia group, n = 13), a normoglycemic control group for the brief hyperglycemia group (n = 12), a group with severe hyperglycemia for 4 hours after the onset of ischemia (prolonged hyperglycemia group, n = 11), a normoglycemic control group for the prolonged hyperglycemia group (n = 13), and a hyperosmolar normoglycemic control group for the prolonged hyperglycemia group (n = 11). Neurologic morbidity and mortality were higher in the two hyperglycemic groups than in the three normoglycemic control groups. The neurologic deficit progressed according to the duration of severe hyperglycemia. In the three normoglycemic control groups neurologic status stabilized 120 minutes after the onset of ischemia, in the brief hyperglycemia group stabilization occurred at 210 minutes, and in the prolonged hyperglycemia group neurologic deficit progressed for approximately 360 minutes, coinciding with the death of all but one gerbil, in which the neurologic deficit remained stable until death 23 hours after ischemia. We suggest that hyperglycemia is another cause of progressing cerebral infarction.

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.

Is atrial fibrillation an independent risk factor for stroke?

That non-rheumatic atrial fibrillation is an independent risk factor for cerebral infarction has not been established with certainty. The rationale underlying contemporary clinical trials of warfarin therapy for the prevention of stroke in patients who have non-rheumatic atrial fibrillation is that the majority of strokes in such patients are due to cardiogenic cerebral embolism. However, there is evidence to suggest that the increased probability of stroke attributed to this arrhythmia is due to its association with other risk factors such as hypertension, diabetes mellitus, and atherosclerosis. The question of who should be anticoagulated is a major public health issue since atrial fibrillation is present in approximately ten per cent of the general population aged 65 or more years.

Medical treatment of transient ischemic attacks: does it influence mortality?

All randomized studies published on the medical treatment of transient ischemic attacks in which controls received no treatment or placebo and in which mortality was reported were reviewed. Using the odds ratio method, we analyzed the results to determine if treatment had an effect on expected mortality. Studies were analyzed separately according to the treatment modality used. Chronic anticoagulation was used in four studies and platelet inhibitors in 12 (14 trials). This meta-analysis showed that neither treatment modality significantly reduces mortality. Chronic anticoagulation may have an adverse effect, and even though platelet inhibitors appeared to reduce mortality, no significance can be demonstrated, and the 95% confidence intervals did not allow us to rule out the possibility, albeit small, of an adverse effect or no effect at all.

Failure of heparin to prevent progression in progressing ischemic infarction

Anticoagulation with heparin is frequently recommended for patients with progressing ischemic cerebral infarction, yet little data is available detailing the acute results of treatment with this agent. We report the results of continuous intravenous heparin treatment in 36 consecutive patients admitted with progressing ischemic infarction, all of whom had computed tomography scans to exclude the diagnosis of hemorrhage prior to treatment. Overall, 18 of 36 (50%) had continued neurologic worsening despite treatment. The incidence of further worsening was greater in carotid territory infarctions (14 of 19, 74%) than in either vertebrobasilar (2 of 8, 25%) or lacunar (2 of 9, 22%) infarctions (p less than 0.05, Fisher's exact test). These observations suggest that additional controlled studies of the efficacy of heparin in progressing ischemic infarction are warranted.

Concurrent morning increase in platelet aggregability and the risk of myocardial infarction and sudden cardiac death

We have previously reported that the frequencies of myocardial infarction and of sudden cardiac death are highest during the period from 6 a.m. to noon. Since platelet aggregation may have a role in triggering these disorders, we measured platelet activity at 3-hour intervals for 24 hours in 15 healthy men. In vitro platelet responsiveness to either adenosine diphosphate (ADP) or epinephrine was lower at 6 a.m. (before the subjects arose) than at 9 a.m. (60 minutes after they arose). The lowest concentration of these agents required to produce biphasic platelet aggregation decreased (i.e., aggregability increased) from a mean +/- SEM of 4.7 +/- 0.6 to 3.7 +/- 0.6 microM (P less than 0.01) for ADP and from 3.7 +/- 0.8 to 1.8 +/- 0.5 microM (P less than 0.01) for epinephrine. The period from 6 to 9 a.m. was the only interval in the 24-hour period during which platelet aggregability increased significantly. We subsequently studied 10 subjects on alternate mornings after they arose at the normal time and after delayed arising. The morning increase in platelet aggregability was not observed when the subjects remained supine and inactive. Thus, there is a temporal association between increased platelet aggregability in the morning and an increased frequency of myocardial infarction and of sudden cardiac death. Demonstration of this association does not establish a cause--effect relation, but together with other evidence linking platelets to these disorders, it may provide insight into the mechanisms precipitating myocardial infarction and sudden cardiac death and aid in the design of more effective preventive measures.

Intravenous prostacyclin in acute nonhemorrhagic stroke: a placebo-controlled double-blind trial

The therapeutic efficacy of prostacyclin in nonhemorrhagic cerebral infarction was assessed in a placebo-controlled double-blind trial. A total of 80 patients with stroke onset within 24 hours were randomized into placebo (37 patients) and prostacyclin (43 patients) groups. Demographic data and risk factors were comparable. Patients in the prostacyclin group received a continuous i.v. infusion of prostacyclin at an average rate of 8.5 ng/kg/min for an average of 64 hours. The placebo group received vehicle only in a similar fashion. During treatment hemodynamic changes were more prominent in the patients receiving prostacyclin and included reduction of systolic and diastolic blood pressure and increase in pulse rate. In contrast there was only a slight (but significant) reduction of diastolic blood pressure in the placebo group. Neurologic deficit scores were determined on admission, at Day 3, and at Weeks 1, 2, and 4. Mean neurologic deficit scores upon entry were comparable in the placebo and prostacyclin groups, and a significant improvement in the score for neurologic deficit was noted in both. The placebo group tended to fare better throughout the study, with a significant difference in neurologic deficit score favoring the placebo group at Week 2 (p = 0.0048). Two patients in the placebo and one in the prostacyclin group died. The only difference in adverse reactions was flushing (6 patients in prostacyclin vs. 0 in placebo group, p less than 0.05). The results of this study suggest a lack of therapeutic efficacy of prostacyclin in a defined population of patients with nonhemorrhagic cerebral infarction.

Usefulness of anticoagulant therapy in the prevention of embolic complications of atrial fibrillation

The medical records of 254 patients with atrial fibrillation were reviewed to determine the incidence of embolic events in relation to type of cardiovascular disease, duration of atrial fibrillation, and use of anticoagulants. During a total follow-up of 833 patient-years in atrial fibrillation, there were 32 instances of systemic embolism: 21 involved the cerebral circulation and 11 were extracerebral. Thirty of these events occurred during 549 patient-years of follow-up without anticoagulation therapy (5.46 of 100 patient-years), while only two embolic events occurred during 284 patient-years on anticoagulants (0.7 of 100 patient-years). Thus, the incidence of embolism was eight times more frequent during the unanticoagulated period of observation in atrial fibrillation (p less than 0.002). The incidence of embolism during follow-up without anticoagulants was the same regardless of the presence or absence of mitral valve disease and regardless of whether atrial fibrillation was chronic or paroxysmal. The rate of serious hemorrhagic complications on anticoagulants was acceptably low (2.11 of 100 patient-years). We conclude that in this study population anticoagulant therapy reduced the risk of embolic complications of atrial fibrillation. The results also indicate that the use of anticoagulants should not be limited to patients with atrial fibrillation due to mitral valve disease.