Prognostic value of beta-thromboglobulin in patients with transient cerebral ischaemia

Coagulation biomarkers for ischemic stroke

A State of the Art lecture titled "coagulation biomarkers for ischemic stroke" was presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2022. Ischemic stroke (IS) is a common disease with major morbidity and mortality. It is a challenge to determine which patients are at risk for IS or have poor clinical outcome after IS. An imbalance of coagulation markers may contribute to the progression and prognosis of IS. Therefore, we now discuss studies on the association of selected coagulation biomarkers from the hemostasis, inflammation, and immunothrombosis systems with the risk of IS, stroke severity at the acute phase, and clinical outcome after treatment. We report on coagulation biomarker-induced risk of IS, stroke severity, and outcomes following IS derived from prospective population studies, case-control studies, and acute-phase IS studies. We found indications that many coagulation and inflammation biomarkers are associated with IS, but it is early to conclude that any of these biomarkers can be applied in a therapeutic setting to predict patients at risk of IS, stroke severity at the acute phase, and clinical outcome after treatment. The strongest evidence for a role in IS was found for beta-thromboglobulin, von Willebrand factor, factor VIII, fibrinogen, thrombin-activatable fibrinolysis inhibitor, D-dimer, and neutrophil extracellular traps, and therefore, they are promising candidates. Further research and validation in large-size populations using well-defined study designs are warranted. Finally, we provide a selection of recent data relevant to this subject that was presented at the 2022 ISTH Congress.

Association between platelet activation and fibrinolysis in acute stroke patients

We aimed to evaluate platelet activation and fibrinolyis in acute atherosclerotic ischemic stroke patients to clarify the relationship between them. Plasma P-selectin antigen, tissue plasminogen activator (tPA) antigen and activity, and plasminogen activator inhibitor-1 (PAI-1) activity were determined in 60 acute atherosclerotic stroke patients and matched control subjects. All patients were examined within 72 h after stroke onset. The levels of P-selectin, tPA antigen, and PAI-1 activity were all significantly higher in stroke patients compared with controls (all p < 0.0001); the level of tPA activity was significantly lower in patients than that in controls (p < 0.0001). These markers did not change much at different time points within 72 h. In stroke group, P-selectin concentration was highly correlated to PAI-1 activity (r = 0.8433, p < 0.001), but not to tPA antigen (r = -0.1752, p > 0.05), and tPA activity (r = 0.2465, p>0.05), which was further confirmed in the multiple linear regression analysis (F = 47.052, p < 0.0001). Our results indicate increased platelet activation and decreased fibrinolysis in patients with acute atherosclerotic ischemic stroke. Increased platelet activation may be correlated with decreased fibrinolysis.

Role of platelet activation in dementia

Platelets play an important role in atherosclerosis, and increased platelet activation is associated with stroke. Stroke is an important risk factor for dementia, as approximately 25% of the patients are demented after stroke. In this review, we describe platelet activation studies in patients with stroke and with dementia. In addition, we review the few studies that have investigated the effect of antiplatelet medication such as aspirin and non-steroidal anti-inflammatory drugs on cognitive function and the occurrence of dementia. We conclude that further studies are needed to characterize the mechanisms and determinants of platelet activation in relation to the development of dementia. Furthermore, the efficacy and safety of antiplatelet intervention will have to be assessed in properly designed randomized trials.

Effects of atrioventricular asynchrony on platelet activation: implication of thromboembolism in paced patients

OBJECTIVE

To investigate the platelet activation in different modes of pacing in patients implanted with dual chamber rate adaptive pacemaker (DDDR) for bradyarrhythmias, and to explore the possible underlying mechanism of the higher thromboembolic incidence in single chamber ventricular rate adaptive (VVIR) pacing.

DESIGN

Platelet activation was determined in chronically paced patients during three different pacing modes (VVIR, DDD, and DDDR) in a randomised crossover fashion.

SETTING

Pacemaker clinic at a university teaching hospital.

PATIENTS

15 patients with complete heart block, mean (SD) age 63 (10) years, and 12 patients with sick sinus syndrome, mean age 68 (9) years, implanted with DDDR pacemakers.

MAIN OUTCOME MEASURES

Platelet activation was assessed by measuring the plasma concentrations of platelet factor 4 (PF4) and beta thromboglobulin using an enzyme linked immunosorbent assay (ELISA). Mean log plasma PF4 and beta thromboglobulin values were compared in paced patients during different pacing modes and with controls.

RESULTS

Compared with controls, patients paced in DDDR, DDD, and VVIR modes had higher mean log plasma concentrations of PF4 (0.90 (0.32), 0.92 (0.29), and 1.12 (0.33) v 0.61 (0.29) log IU/ml, all p < 0.05, respectively) and beta thromboglobulin (1.55 (0.20), 1.59 (0.16), and 1.71 (0.18) v 1.40 (0.12) log IU/ml, all p < 0.05, respectively). In paced patients, VVIR pacing was associated with higher plasma concentrations of PF4 and beta thromboglobulin than either DDDR or DDD pacing (all p < 0.05). There was no significant difference in plasma PF4 and beta thromboglobulin between patients with complete heart block and sick sinus syndrome in the corresponding pacing mode. Holter monitoring showed no difference in mean pacing rate and occurrence of cardiac arrhythmias to account for the increased platelet activation during VVIR pacing. There was no relation between the percentage of ventricular pacing on Holter during DDDR, DDD, and VVIR modes and the log mean plasma concentrations of PF4 (r = 0.002, 0.001, and 0.001, respectively, all p > 0.05) and beta thromboglobulin (r = 0.007, 0.01, and 0.001, respectively, all p > 0.05).

CONCLUSIONS

Single chamber ventricular pacing was associated with enhanced spontaneous systemic platelet activation compared with physiological dual chamber pacing. This was related to the loss of atrioventricular synchrony rather than to the underlying cause of bradycardia, lack of rate response, or coexisting arrhythmia. This abnormality may be associated with increased thromboembolism and was correctible by an appropriate pacing mode prescription and possibly antiplatelet treatment.

Sustained activation of blood coagulation in patients with cerebral thrombosis

Recent progress in the measurements of the hemostatic markers enables us to assess the detailed profiles of hemostatic activation in various diseases. To evaluate the degree of hemostatic system activation in patients with cerebral thrombosis, detailed coagulation studies were performed in 28 patients with acute-phase cerebral thrombosis and in 36 with chronic-phase cerebral thrombosis, together with 6 with chronic-phase cerebral hemorrhage and 37 age-matched healthy volunteers. In both acute-phase and chronic-phase cerebral thrombosis, plasma levels of thrombin-antithrombin III complex, plasmin-alpha 2-plasmin inhibitor complex and D-dimer were significantly higher, and antithrombin III and protein C were significantly lower than those in the normal group. Plasma fibrinogen concentration was significantly higher in chronic-phase cerebral thrombosis than that in chronic-phase cerebral hemorrhage. No significant difference was found in these variables between acute-phase and chronic-phase cerebral thrombosis. In addition, there was no difference in these parameters between chronic phase cerebral hemorrhage and normal subjects. These findings indicate that a sustained activation of coagulation and fibrinolysis is present in cerebral thrombosis, and it might contribute to the pathogenesis of cerebral thrombosis.

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.

Single-dose effect of enteric-coated aspirin on platelet function and thromboxane generation in middle-aged men

OBJECTIVE

To evaluate the effect of a single dose of enteric-coated aspirin (ECA) in three different dosages on platelet function and thromboxane generation in middle-aged men.

DESIGN AND METHODS

In a nonblind, nonplacebo-controlled, crossover study, a single dose of ECA (50, 250, or 1000 mg) was given in a tablet form to a group of healthy, middle-aged men. Ten subjects, aged 50-67 years, volunteered to participate in this study. Platelet functions including bleeding time, platelet aggregation, adenine nucleotides, beta-thromboglobulin, platelet factor 4, thromboxane generation, and aspirin measurement were determined.

RESULTS

Before ECA ingestion, the intracellular adenine nucleotides (adenosine triphosphate, adenosine diphosphate) were decreased, and both beta-thromboglobulin and platelet factor 4 were increased. These observations suggested that platelets were activated in vivo in middle-aged men. These findings returned to normal within 8 hours after the ingestion of ECA, and maintained normal for at least two days. Bleeding time was significantly prolonged at 8 and 24 hours compared with that before ingestion of ECA 1000 mg (p < 0.05). The generation of platelet thromboxane was maximally inhibited by approximately 40 percent in the samples 8 hours after ECA ingestion. Abnormal values of adenine nucleotides, beta-thromboglobulin, and platelet factor 4 returned to normal within 8 hours. Arachidonic acid-induced platelet aggregation was inhibited compared with that before treatment (p < 0.01) and the inhibitory effect was maintained for at least three days. Adenosine diphosphate- and epinephrine-induced aggregations were less inhibited than those induced by arachidonic acid. Inhibitory effects of ECA on platelet aggregation were dose dependent.

CONCLUSIONS

Our study indicates that platelets are activated in middle-aged men and that a single dose of ECA 50 mg is safe and can inhibit thromboxane synthesis and platelet aggregation. These results suggest that a daily dose of ECA 50 mg may be useful for blocking platelet activation and preventing thrombosis.

Increased thromboxane biosynthesis in patients with acute cerebral ischemia

BACKGROUND AND PURPOSE

Clinical and experimental studies suggest that platelets have a major role in the pathogenesis of cerebral ischemia. However, ex vivo both platelet aggregation studies and measurements of platelet-derived products in patients with cerebral ischemia have shown inconsistent results. The present study was designed to resolve this inconsistency.

METHODS

We have measured the urinary excretion of a thromboxane metabolite, 11-dehydro-thromboxane B2, by a previously validated radioimmunoassay technique in 51 patients with acute cerebral ischemia who had experienced either a transient ischemic attack (14 patients) or an ischemic stroke (37 patients) and in 20 control patients with nonvascular neurological disorders. The median time between the onset of symptoms and urine sampling was 24 hours (range, from 2 hours to 8 days).

RESULTS

The excretion rate of immunoreactive 11-dehydro-thromboxane B2 ranged between 39 and 478 pmol/mmol creatinine in patients with a transient ischemic attack and between 23 and 5,916 pmol/mmol creatinine in stroke patients, with 29% (p = 0.18) and 51% (p = 0.004) of the urine samples, respectively, exceeding the upper limit of the control samples (251 pmol/mmol creatinine [mean +/- 2 SD]) (p = 0.01). In stroke patients, metabolite excretion was not related to the type (cortical or "lacunar") or site of cerebral infarction. Low-dose aspirin (50 mg per day for 7 days) reduced the urinary excretion by approximately 85% in 11 consecutive stroke patients.

CONCLUSIONS

We conclude that 1) episodes of enhanced thromboxane biosynthesis are detected infrequently in patients with a transient ischemic attack, 2) aspirin-suppressible episodes of increased thromboxane formation can be detected during the early phase of acute ischemic stroke, and 3) this finding may provide a rationale for testing the efficacy and safety of this drug in this setting.

The topography of microthrombi in ischemic brain infarct

Following cerebral ischemia a tendency to increased coagulation can be detected. Vascular occlusion may develop either as a result of local thrombus formation or from emboli caused by circulating platelet aggregates. We studied the localization of microthrombi and their effects on tissue in double-hemisphere sections. Fresh brain infarcts showed a large number of microthrombi limited to the ischemic region. In more advanced infarcts they were found mainly at the border of the necrosis and diffusely distributed over both hemispheres. Older, subsiding infarcts showed only isolated microthrombi limited to the area of the necrosis. This indicates that great importance must be attached to microthrombi in infarct progression.

Headache in transient or permanent cerebral ischemia. Dutch TIA Study Group

We studied headache features in 3,126 patients with acute cerebral or retinal ischemia. Headache occurred in 18% of these patients (in 16% of all patients with transient ischemic attacks, in 18% of patients with reversible ischemic neurologic deficits, and in 19% of patients with minor strokes) and was mostly continuous in all types of attacks. Headache was present in 16% of patients with monocular visual symptoms. The occurrence of headache was not related to the mode of onset, mode of disappearance, or duration of the attack. Patients with headache more often were known to have heart disease. Headache was less frequent in patients with small deep infarcts, who were more often hypertensive, and in patients with infarcts in the anterior circulation; headache was more frequent in patients with cortical infarcts and in patients with infarcts in the posterior circulation. Patients with a relevant small deep infarct on computed tomographic scan and accompanying headache relatively often reported symptoms compatible with cortical ischemia, such as language disorders or a visual field defect. We conclude that headache is a frequent accompanying symptom in patients with acute cerebral and retinal ischemia and that the occurrence of headache is partly related to the underlying cause of the ischemic lesion.

Platelet aggregation in transient global amnesia

We found a correlation between increased platelet aggregation parameters and transient global amnesia and no differences between patients with transient global amnesia and transient ischemic attacks. Our findings support the theory of a vascular mechanism for transient global amnesia.

Anticoagulant drugs in the elderly: valuable in selected patients

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Beta-thromboglobulin in cerebral infarction

Plasma beta-thromboglobulin (BTG) was significantly elevated in the acute phase of 116 atherosclerotic thrombotic (p less than 0.0001) and 36 cardioembolic (p less than 0.005) infarcts but normal for 96 lacunes compared with controls. This elevation persisted into the 6th week after the acute event. Among atherosclerotic thrombotic infarcts, the acute beta-thromboglobulin level showed a tendency to correlate with infarct size on CT and predicted mortality at 6 weeks. These results suggest that platelet aggregation plays a primary role in the pathogenesis of atherothrombosis.

Platelet function and thrombin activity in patients with recent cerebral transient ischemic attacks

Platelet function and thrombin activity were investigated in 12 hospitalized patients (7 men and 5 women, mean age 53 years) who had had transient cerebral ischemic attacks in the previous 2-12 weeks. Each patient was given an extensive clinical and instrumental evaluation, including Doppler sonography of the cervical and lower limb vessels, cerebral angiography, and head computed tomography scan, after which relevant atherosclerotic disease was excluded. The controls consisted of 12 subjects hospitalized for nonvascular neurologic problems and matched for age, sex, and risk factors to the transient ischemic attack patients. Collagen-induced platelet thromboxane B2 production, plasma beta-thromboglobulin, and fibrinopeptide A were significantly higher in the patients than the controls. Platelet aggregability by collagen was the same in the 2 groups. Platelet hyperfunction and enhanced thrombin activity are present in patients some weeks after the acute episode, suggesting that the hemostatic system has a primary pathogenetic role.

No effect of acetylsalicylic acid on B-thromboglobulin and platelet factor 4 plasma levels in patients with transient ischaemic attacks

We studied the effect of acetylsalicylic acid (ASA) versus placebo on B-thromboglobulin (B-TG) and platelet factor 4 (PF4) plasma levels and ADP-induced platelet aggregation in 25 male patients with transient ischaemic attacks (TIA). The patients were allocated randomly to two groups: 14 patients received oral treatment with ASA 500 mg b.i.d. for 14 days, 11 patients placebo b.i.d. for the same period. B-TG and PF4 plasma levels and ADP-induced platelet aggregation were determined in basal conditions, and two hours, and seven and fourteen days after starting with ASA or placebo. In addition, the same parameters were studied in a group of 20 healthy males of matched age. Basal levels of plasma B-TG and PF4 and the maximal amplitude of ADP-induced platelet aggregation were abnormally high in TIA patients. ASA caused a significant reduction of B-TG plasma levels in TIA patients 2 hours after the first administration, but no effect was observed at the 7th and 14th day of treatment. PF4 plasma levels were unaffected by ASA treatment. It is concluded that ASA, at the dose conventionally used in clinical trials, does not affect the release of two alpha-granule proteins.

Plasma levels of platelet secretory proteins

Platelets contain three types of secretory organelles: the dense granules, the alpha granules, and the lysosomes. Most of the proteins secreted from platelets are stored in the alpha granules, whereas the dense granules contain substances such as adenine nucleotides, serotonin, Ca++, and inorganic pyrophosphate types as well as a heparatinase. Three of the secreted alpha granule proteins have been measured by radioimmunoassay and it has been suggested that levels of these proteins in patient plasmas provide an index of in vivo platelet activation and secretion. These three are beta-thromboglobulin, platelet factor 4, and thrombospondin. In this chapter the chemistry of these proteins will be considered briefly, as will their clearance from the circulation, and then the clinical studies will be reviewed critically. Since radioimmunoassays were developed for these proteins (the first was reported in 1975), there has been a profusion of reports on levels of one or another of these proteins in a wide range of disease states, and these reports have indicated secreted platelet protein levels ranging from normal to grossly elevated in a given disease state. Possible reasons for such variability will be discussed.

Blood lipid profile in healthy subjects treated with ticlopidine

The study was carried out in order to evaluate if Ticlopidine induces lipid metabolism changes. Twenty seven healthy subjects were studied, 14 with placebo and 13 with Ticlopidine treatment (500 mg/day), for 30 days. Total cholesterol, HDL cholesterol, triglycerides, apolipoproteins A and B were evaluated before and after treatment. No significant changes of the blood lipid parameters were observed.

Enhanced in vivo platelet activation in subtypes of ischemic stroke

It remains uncertain whether platelet activation in ischemic stroke is contributory or secondary to brain ischemia. The efficacy of aspirin (ASA) in stroke prevention suggests that platelet activation contributes to the occurrence of stroke. On the other hand, platelet activation may be simply a generalized consequence of cerebral ischemic damage. To examine this issue, plasma levels of the platelet specific proteins beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) were measured in fifty-eight patients with various defined types of acute ischemic strokes. beta-TG was a broader indicator of platelet activation than PF4. Compared with an age-matched control group, thromboembolic and cardioembolic stroke patients had significantly elevated beta-TG levels (p less than 0.001). Also, beta-TG levels in these stroke categories were significantly higher in samples drawn within the first week after the event than in those drawn later (p less than 0.001). In contrast, beta-TG levels in lacunar stroke patients and in most TIA patients were normal. beta-TG levels did not correlate with the volume of cerebral infarction as measured by planimetry from CT scans. Moreover, beta-TG levels in patients on chronic ASA therapy at the time of stroke did not differ from those in patients of the same diagnostic categories not taking aspirin. These data indicate that platelet activation may be important in some, but not all, subtypes of ischemic stroke and that platelet activation can occur in stroke even though the platelet cyclooxygenase pathway is suppressed.

The effect of ketanserin, a 5-HT2-receptor antagonist, on 5-hydroxytryptamine-induced irreversible platelet aggregation in patients with cardiovascular diseases

Platelet aggregation in response to 5-hydroxytryptamine was investigated in 40 normal subjects, in 45 patients with acute myocardial infarction, and in 65 patients with peripheral arterial obstructive disease. It was found that of the 110 patients with cardiovascular disease, 40% had a biphasic irreversible platelet aggregation, whereas this phenomenon occurred in only 7.5% of the normal population. A double-blind placebo-controlled study further showed that a subacute treatment with ketanserin, a selective 5-HT2-receptor antagonist both on platelets and on vascular tissue, efficiently abolished the irreversible platelet aggregation in patients hyperreactive to 5-hydroxytryptamine. In an additional open study, including 10 patients with peripheral arterial obstructive disease, a chronic treatment with ketanserin 40 mg t.i.d. for a period of 3 months significantly suppressed the primary platelet aggregation to 5-HT at 2 X 10(-5) M and at 2 X 10(-6) M and significantly lowered the plasma beta thromboglobulin levels. Since 5-HT is a potent mediator of vasospasm, treatment with ketanserin might be of therapeutic value in atherosclerotic diseases, where platelet activation is thought to be involved.

Hemostatic Balance Index in TIA patients: sex-related changes

In order to evaluate the occurrence of hemostatic disorders, 37 patients with transient ischemic attacks (TIAs) and 50 control subjects were studied by means of the Hemostatic Balance Index (H.B.I.) derived from Raby's Thrombodynamic Potential Index (T.P.I.) and Fearnley's Whole Blood Diluted Lysis Time (W.B.D.L.T.). Results showed a significant increase in T.P.I. and a tendency to a decrease in fibrinolytic activity in the TIA group: H.B.I. was shown to be significantly increased, thus indicating a pro-thrombotic imbalance in these patients. The occurrence of similar changes in TIA females when compared to male patients marks the importance of plasmatic factors in the mechanism of thrombotic disorders in females with cerebrovascular disease.

Delayed cerebral ischemia following arteriography

Cerebral ischemic events associated with arteriography are usually attributed to catheter-induced emboli. We present three patients with cerebral ischemia occurring 6 to 48 hours post-arteriography. We suspected that alternate pathogenic mechanisms were in effect. To evaluate the possibility that sustained platelet activation occurs in association with arteriography, we measured the platelet-specific protein beta thromboglobulin (BTG) prior to and 24 hours following arteriography in two groups of patients. Group I had arteriography performed shortly after venipuncture, while Group II patients did not have arteriography between samples. Seven of eight Group I patients had an increase of BTG on day two, compared with two of eight group II patients (p less than 05). When compared to Group II changes, Group I had a significant increase of BTG on day two (p less than .05). We conclude that cerebral ischemic events associated with arteriography may occur on a delayed basis, and that platelet activation, manifested by increased BTG levels, may be one mechanism contributing to this phenomenon.

Malondialdehyde-like material and beta-thromboglobulin plasma levels in patients suffering from transient ischemic attacks

Beta-thromboglobulin (betaTG) and malondialdehyde-like material (MDA-LM) plasma levels were studied in patients affected by transient ischemic attacks (TIA) after 2-4 months from the last episode. BetaTG and MDA-LM values were significantly higher in TIA patients than in 20 controls matched for age. No correlation between MDA-LM and betaTG was seen. This study suggests that in vivo platelet activation and, likely, increase of platelet cyclo-oxygenase activity can be detectable in TIA patients.

Platelets, carotids, and coronaries. Critique on antithrombotic role of antiplatelet agents, exercise, and certain diets

"Antiplatelet" drugs and certain life styles seem to have an "antithrombotic" effect that may help protect against stroke and heart attack. This review of the experience with aspirin, dipyridamole, and sulfinpyrazone offers new interpretations of some of the major clinical trials, suggests guidelines for use of antiplatelet drugs, and integrates novel observations on diet and exercise into the "thromboxane-prostacyclin balance" hypothesis. It is argued that the Canadian stroke study showed that aspirin protects men with transient ischemic attacks from coronary death as well as from stroke, that type II errors may have been made in some clinical trials, that aspirin protects women as well as men, that aspirin benefits patients who have had a heart attack, that the effect of aspirin in angina varies with the type of angina, that the dose of aspirin used may not be critical, that guidelines for use of dipyridamole and sulfinpyrazone are still inconclusive, and that exercise and fish oil supplements may be "antithrombotic."