Hypercoagulability in acute ischemic stroke: analysis of the extrinsic coagulation reactions in plasma by a highly sensitive automated method

Hypercoagulopathy in Stroke Patients with Nonvalvular Atrial Fibrillation: Hematologic and Cardiologic Investigations

The coagulation system is activated and coagulation activation markers are elevated in acute ischemic stroke with nonvalvular atrial fibrillation (NVAF). The etiology, severity, and prognosis of the ischemic stroke might be estimated with the level of the activation of the coagulation system. In this study, prothrombin F1+2 (F1+2), D-dimer, and fibrinogen levels were measured in patients with acute ischemic stroke with and without NVAF, and stroke severity was compared with these hemostatic parameters. Of 55 patients, 29 had sinus rhythm (group I), 26 had NVAF (group II); 20 healthy subjects (group III) were included in the study. Subtypes of cerebral infarction were classified. The patients underwent stroke severity, electrocardiography, echocardiography, cranial computed tomography, cervical duplex ultrasonography, and hemostatic parameter studies. In group II, F1+2 level (2.83±0.89) was significantly higher than in group I (2.33±0.80) and III (1.94±0.64) (p values: group I-II, 0.036; groups II-III, 0.001; groups I-III, 0.104). In group III, fibrinogen level (251.64±60.96) was significantly lower than that in groups I (347.97±111.49) and II (364.04±86.20) (p=0.001). D-dimer was not significantly different between groups. In group I, lacunar syndrome (LACS), and in group II, partial and total anterior circulation syndrome (PACS+TACS) were more common (p=0.013, p=0.001, respectively). In group II, Scandinavian Stroke Scale scores were lower than those in group I (group I=45.2±14, group II=35.4±18.9, p=0.02). In conclusion, activation of coagulation, demonstrated by increment F1+2, is more abundant in the stroke patients with NVAF than in the stroke patients with sinus rhythm. Our results also showed that activation of the hemostatic system might be related to stroke subtype and stroke severity. It is suggested that the oral anticoagulation treatment as prophylaxis is important in the prevention of stroke in patients with NVAF.

The simultaneous occurrence of both hypercoagulability and hypofibrinolysis in blood and serum during systemic inflammation, and the roles of iron and fibrin(ogen)

Although the two phenomena are usually studied separately, we summarise a considerable body of literature to the effect that a great many diseases involve (or are accompanied by) both an increased tendency for blood to clot (hypercoagulability) and the resistance of the clots so formed (hypofibrinolysis) to the typical, 'healthy' or physiological lysis. We concentrate here on the terminal stages of fibrin formation from fibrinogen, as catalysed by thrombin. Hypercoagulability goes hand in hand with inflammation, and is strongly influenced by the fibrinogen concentration (and vice versa); this can be mediated via interleukin-6. Poorly liganded iron is a significant feature of inflammatory diseases, and hypofibrinolysis may change as a result of changes in the structure and morphology of the clot, which may be mimicked in vitro, and may be caused in vivo, by the presence of unliganded iron interacting with fibrin(ogen) during clot formation. Many of these phenomena are probably caused by electrostatic changes in the iron-fibrinogen system, though hydroxyl radical (OH˙) formation can also contribute under both acute and (more especially) chronic conditions. Many substances are known to affect the nature of fibrin polymerised from fibrinogen, such that this might be seen as a kind of bellwether for human or plasma health. Overall, our analysis demonstrates the commonalities underpinning a variety of pathologies as seen in both hypercoagulability and hypofibrinolysis, and offers opportunities for both diagnostics and therapies.

Hospitalized osteoporotic vertebral fracture increases the risk of stroke: a population-based cohort study

The association between osteoporosis and cardiovascular diseases has been demonstrated. Higher cardiovascular risk has also been correlated with vertebral fractures. However, the association between osteoporotic vertebral fracture and the possibly higher risk of stroke remains uncertain. This study aimed to evaluate the incidence, risk, and type of stroke in patients with osteoporotic vertebral fracture. Patients with osteoporotic vertebral fracture were identified (n = 380) and 10 age- and sex-matched controls per case (comparison group, n = 3795) were chosen from a nationwide representative cohort of 999,997 people from 1998 to 2005. Both groups were followed-up for stroke events for 3 years, matched by propensity scores with adjustments for covariates such as comorbidities (ie, hypertension, diabetes, arrhythmia, or coronary heart diseases) and exposure to medications (ie, aspirin, lipid lowering drug, or nitrates), and assessed by Kaplan-Meier and Cox regression analyses. The incidence rate of stroke in the osteoporotic vertebral fracture group (37.5 per 1000 person-years; 95% confidence interval [CI], 27.5-51.2) was significantly higher than in the comparison group (14.0 per 1000 person-years; 95% CI, 12.0-16.4, p < 0.001). Stroke was more likely to occur in the osteoporotic vertebral fracture patients than in the normal controls (crude hazard ratio [HR] 2.68, 95% CI 1.89-3.79, p < 0.001; adjusted HR 2.71, 95% CI 1.90-3.86, p < 0.001). In conclusion, patients with osteoporotic vertebral fracture have a higher risk of stroke (ie, both ischemic and hemorrhagic) and require stroke prevention strategies.

Von Willebrand factor, P-selectin and fibrinogen levels in patients with acute ischaemic and haemorrhagic stroke, and their relationship with stroke sub-type and functional outcome

Although ischaemic stroke is associated with accentuated platelet function, it remains unclear whether this applies to all sub-types, especially lacunar infarcts, which differ from cortical infarction in their patho-aetiology. Similarly, conflicting evidence suggests that haemorrhagic stroke may, or may not, be associated with a hypothrombotic state. Levels of von Willebrand factor (vWF), fibrinogen, and P-selectin were measured within 48 h of ictus in 163 patients with acute ischaemic stroke and 40 patients with acute primary intracerebral haemorrhage, and 33 age, gender and race matched-controls. vW F (IU/dl) was significantly increased in both cortical and lacunar ischaemic stroke, and haemorrhagic stroke, as compared with controls, median (semiquartile range): 158 (25) vs 144 (19) vs 147 (24) vs 114 (16), respectively. Similarly, fibrinogen (g/litre) was increased: 4.80 (0.90) vs 4.65 (0.70) vs 4.35 (0.83) vs 3.70 (0.70). In contrast, soluble P-selectin (ng/ml) was increased in cortical stroke as compared with lacunar infraction patients or controls: 408 (101) vs 300 (108) vs 324 (121), respectively; P-selectin was not increased in haemorrhagic stroke, 360 (153). Both vW F and fibrinogen correlated with 3-month functional outcome (modified Rankin score): r = 0.371 (2 P = 0.0006), and r = 0.195 (2 P = 0.042), respectively; however, P-selectin was not associated with outcome: r = 0.188 (2 P = 0.084). The results suggest that increases in vW F and fibrinogen in all types of stroke reflect an acute phase response; in contrast, increased soluble P-selectin levels in cortical stroke, but not lacunar infarction, suggest that platelets contribute to the patho-aetiology of some subtypes of ischaemic stroke.

New asymptomatic ischemic lesions on diffusion-weighted imaging after cerebral angiography

BACKGROUND AND PURPOSE

We investigated the frequency of new lesions on diffusion-weighted imaging (DWI) after conventional cerebral angiography (CAG) in acute stroke patients and associated factors.

METHODS

Fifty-six acute stroke patients with CAG and 55 stroke patients without CAG (controls) underwent DWI twice, within 48 h before and after CAG, and within 48 h and 7 days after onset, respectively. The frequency of new DWI lesions was then compared between the two groups. Next, we divided the CAG group patients into two groups according to the presence of new DWI lesions after CAG (Positive and Negative groups), and the factors associated with new DWI lesions were investigated by multivariate logistic regression analysis.

RESULTS

New DWI lesions were more often observed in the CAG group than the Control group (43% versus 31%, p=0.192). In the CAG group, mean fluoroscopy time was longer in the Positive group than the Negative group (26.5 min versus 14.9 min, p<0.001). Sensitivity and specificity analysis demonstrated a fluoroscopy time of 17 min to discriminate the Positive and Negative groups. Multivariate logistic regression analysis demonstrated that a fluoroscopy time of over 17 min was independent factor associated with new DWI lesions after CAG (OR, 9.4, 95% CI 1.8 to 48.6, p=0.0078).

CONCLUSION

New DWI lesions were more often seen in patients with CAG than without CAG. However, the difference in number of DWI abnormalities did not reach statistical significance. In CAG patients, fluoroscopy time appears to be an independent factor associated with new DWI lesions.

Observation on tissue factor pathway and some other coagulation parameters during the onset of acute cerebrocardiac thrombotic diseases

It is widely recognized that thrombosis is the major event in the evolution of acute myocardial infarction (AMI) and acute ischemic stroke (AIS). But the contribution of coagulation factors to the development of ischemic arterial diseases is still not clearly established. The goal of this study was to establish the possible relationship between coagulation factors as well as anticoagulant and the onset of AMI and AIS. The study population consisted of 69 patients with AMI and 71 with AIS as well as 50 age-matched healthy volunteers. Compared with the control group, plasma tissue factor (TF) and tissue factor pathway inhibitor (TFPI) activities and both TF and TFPI antigens were significantly higher in the AMI group; plasma TF activity and antigen in AIS group were significantly increased, but the activity and antigen of plasma TFPI were significantly decreased in the AIS group. Plasma FVII coagulation (FVII:C) activity was markedly higher in patients with AIS, but not statistically different to the control in patients with AMI. FVIII coagulation (FVIII:C) activity was remarkably higher in patients with AMI but slightly lower than the control in patients with AIS. In the AMI and AIS groups, prothrombin activity and clottable fibrinogen were significantly higher and plasma antithrombin III activity was remarkably lower than the control. The results suggested that during the onset of AMI and AIS, the initiation of TF pathway would be associated with the thrombotic events and that the blood be in hypercoagulable state. But the changes of FVII:C, TFPI and FVIII:C in AMI are different from those in AIS.

Anticoagulant therapy with a selective thrombin inhibitor for acute cerebral infarction: usefulness of coagulation markers for evaluation of efficacy

BACKGROUND

Argatroban is a selective thrombin inhibitor used for the treatment of atherothrombotic infarction. We evaluated its therapeutic effect using coagulation markers in 30 patients with cardioembolic infarction and 30 patients with atherothrombotic infarction during the immediate period after ischemic stroke.

METHODS

Argatroban therapy was initiated within 24 hours of the onset of stroke and the course was followed until 7 days after the start of treatment. Neurological evaluation was performed using the Hemispheric Stroke Scale (HSS). We also monitored the serial changes in activated partial thromboplastin time, prothrombin time, thrombin-antithrombin complex (TAT), and prothrombin fragments 1 + 2 (F1 + 2).

RESULTS

Both groups of patients showed significant improvement of HSS after 7 days of argatroban therapy (p < 0.05). Hemorrhagic infarction developed in 8 of patients with cardioembolic infarction, but no worsening of symptoms was noted in any of these patients. There was no significant prolongation of activated partial thromboplastin time or prothrombin time after 7 days, while levels of both TAT and F1 + 2 were significantly decreased from day 2.

CONCLUSION

The decrease in TAT and F1 + 2 during argatroban therapy suggested improvement of hypercoagulability, which might explain how this drug prevents the recurrence of both ATI and CEI in the acute stage. Our findings also suggested that TAT and F1 + 2 might be useful indices for evaluation of argatroban efficacy.

Natural anticoagulants (antithrombin III, protein C, and protein S) in patients with mild to moderate ischemic stroke

BACKGROUND AND PURPOSE

The role of the natural anticoagulants, antithrombin III (AT III), protein C (PC), and protein S (PS), in patients with mild to moderate ischemic stroke remains uncertain. We aimed to find out whether their levels in peripheral blood correlated with the severity of neurological deficit or can predict clinical outcome and recurrence.

METHODS

We studied AT III, PC, and free PS levels in 55 consecutive patients likely to survive the study period on admission, 1 week, 1 month and 3 months after a first-ever ischemic stroke. Sex- and age-matched controls were studied once. All patients underwent a full neurological examination and blood sampling at each study time point; comprehensive stroke risk factors were recorded, and the etiology of the ischemic stroke was determined. All patients were contacted 3 years later for possible recurrent ischemic events.

RESULTS

AT III level was found to be significantly lower at all time points after stroke; PC level was significantly increased on admission and normal at subsequent measurements, and PS level was normal on admission but significantly decreased later. The levels of the natural anticoagulants did not correlate with the etiology of stroke, any stroke risk factor, or neurological scores, except that the AT III level on admission showed significant correlation with stroke severity and disability at 3 months. Natural anticoagulant levels did not predict recurrence of ischemic stroke.

CONCLUSIONS

The measurements of the level of AT III, PC, or PS did not deliver useful information for management of patients with mild or moderate ischemic stroke, expect that AT III level on admission might predict outcome.

Hemostatic activation in acute ischemic stroke

BACKGROUND AND PURPOSE

The purpose of this study was to examine the association between hemostatic activation and stroke severity, and to provide data on hemostatic variables in acute ischemic stroke.

METHODS

The patient material comprised 76 consecutive patients with acute ischemic stroke (median 16 h, interquartile range 3-48). Levels of hemostatic variables were determined in blood samples collected on the day of hospitalization. Stroke severity was assessed on admission by the Oxfordshire Community Stroke Project (OCSP) classification, and on discharge (median 9 days, interquartile range 6-14) by Barthel Index (BI, scores 0-50, 55-90, or 95-100) and modified Rankin Scale (mRS, scores 0-1 or 2-6). Associations were assessed by multiple linear regression analyses.

RESULTS

Levels of the fibrin degradation product D-Dimer and the activation peptide prothrombin fragment 1 + 2 (F1 + 2) were linearly related to stroke severity, whether assessed on admission (P = .001 and.03, respectively, for the OCSP classification), or on discharge (P = .009 and.43, respectively, for BI; and.001 and.05, respectively, for mRS). High levels of D-Dimer and F(1 + 2), as well as low levels of antithrombin and protein C were also present in patients with a presumed embolic source, and low antithrombin or protein C was borderline significantly associated with atrial fibrillation (P = .072 and.058, respectively). Low levels of protein C or protein S, and the presence of antiphospholipid antibodies, including lupus anticoagulant (LA), was detected in 13/73 (18%) and 15/70 (21%) of the patients, respectively.

CONCLUSION

Activation of the hemostatic system is independently related to acute stroke severity and short-term outcome. Low levels of coagulation inhibitors or presence of antiphospholipid antibodies is a relatively frequent finding in unselected patients with acute ischemic stroke, but a causative role cannot be inferred from our study.

Antithrombin-III Activity and the Efficacy of Heparin in Progressing Ischemic Stroke

Heparin is often used in progressing ischemic stroke. However, a substantial part of the patients continue to progress while on treatment. The purpose of this study was to evaluate if antithrombin (AT) III activity before treatment could predict patients at risk for continued progression or if heparin-induced reduction in AT-III activity during treatment is related to continued progression. The study included 42 acute stroke patients with heaprin treatment for progression of isch emic stroke. The patients were continuously supervised for progression. Intravenous heparin therapy was started as soon as possible after the progression was noticed. Antithrombin-III activity was assessed before initiation of treatment and daily during the treatment period. Nine (21 %) of the 42 patients continued to progress while on treatment. There was no statis tically significant difference in AT III activity before treatment between patients who continued to progress and those where the progression ceased when treatment was initiated. Nor were there any differences in the mean AT III activity levels during treatment for patients with more or less favorable clinical course. The individual changes (Δ AT III) were similar in both patient groups as was the proportion of patients with their low est AT III activity in the thrombogenic range (continued: 22% vs. ceased: 27%). No clinically relevant influence of AT III activity on heparin efficacy in progressing ischemic stroke was found. Key Words: Stroke progression—Heparin treatment— Antithrombin activity.

Effect of bezafibrate on hypercoagulability assessed by fluorogenic prothrombin time in hyperlipidemic patients with non-insulin-dependent diabetes mellitus

We investigated the usefulness of the fluorogenic prothrombin time (FPT) for detection of hypercoagulability and its association with hyperlipidemia in 19 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 10 healthy control subjects, compared with plasma levels of fibrinogen, plasminogen activator inhibitor-1 (PAI-1) and D-dimer. We also evaluated the effect of bezafibrate on hypercoagulability in 10 hyperlipidemic NIDDM patients. The plasma levels of FPT and fibrinogen were significantly higher in hyperlipidemic NIDDM patients than in normolipidemic NIDDM patients and controls. Plasma levels of PAI-1 and D-dimer were significantly higher in normolipidemic and hyperlipidemic NIDDM patients compared with controls. The FPT was correlated with the HbA1c, the body mass index, and levels of total cholesterol, fibrinogen and PAI-1. Six-months therapy with bezafibrate reduced the levels of FPT, triglycerides and basal insulin, but did not alter levels of fibrinogen, PAI-1 and D-dimer. Our results showed that the FPT was useful for detection of hypercoagulability and evaluation of the effect of drugs. The increased FPT in patients with NIDDM suggested that hypercoagulability was present in association with hyperlipidemia.

Polymorphisms of the factor VII gene and circulating FVII:C levels in relation to acute cerebrovascular disease and poststroke mortality

BACKGROUND AND PURPOSE

FVII:C has been shown to be an independent risk factor for myocardial infarction and is related to environmental and genetic factors. This study sought to investigate FVII:C levels and factor VII (FVII) gene polymorphisms in relation to stroke and disease outcome.

METHODS

To examine the association of FVII:C and the Msp I and promoter insertion polymorphisms of the FVII gene in acute stroke, 317 patients and 198 age-matched control subjects were studied.

RESULTS

FVII:C levels were significantly lower in patients at onset than 3 months later (119% versus 135%, respectively; P < .0005). Levels were significantly lower in patients at onset than in control subjects (124% [95% confidence interval, 120% to 129%] versus 141% [95% confidence interval, 135% to 148%], respectively; P < .0005) but were not significantly different at 3 months (135% [95% confidence interval, 128% to 141%] versus 141% [95% confidence interval, 135% to 148%], respectively). We found no difference in genotype distribution for either polymorphism between patients and control subjects, no difference in FVII:C level or genotype distribution between pathological types of stroke, and no relationship with poststroke mortality. Both polymorphisms were significantly associated with FVII:C levels in patients and control subjects. In a multiple regression model for patients, Msp I genotype, cholesterol, and smoking remained as independent predictors of FVII:C levels, accounting for 32% of interindividual variation.

CONCLUSIONS

These results suggest that neither FVII:C levels nor FVII gene polymorphisms are associated with cerebrovascular disease. There were no genotype-specific correlations of environmental factors with FVII:C, but there was evidence of an acute-phase or consumptive fall in FVII:C levels at the time of stroke, whereas levels increased to those similar for healthy age-matched control subjects by 3 months, when the acute phase had presumably subsided.

Fibrinogen, coagulation factor VII, tissue plasminogen activator, plasminogen activator inhibitor-1, and lipid as cardiovascular risk factors in chronic hemodialysis and continuous ambulatory peritoneal dialysis patients

Mortality rates associated with cardiovascular disease (CVD) are high in long-term dialysis patients. Increased levels of plasma fibrinogen (FBG), coagulation factor VII (FVII), tissue plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1) as well as hyperlipidemia are regarded as important risk factors for CVD. To investigate whether there are differences in the risk of CVD between chronic hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients, serum lipid levels and plasma FBG, FVII, t-PA, and PAI-1 levels were measured in 17 patients on HD and 17 patients on CAPD. FBG was measured by the thrombin time method, FVII activity (FVIIc) by the chromogenic prothrombin time method, and t-PA and PAI-1 activity by the chromogenic substrate assay. No difference was found in body mass index (BMI) between HD and CAPD patients. Total cholesterol (TC), TC/high-density lipoprotein (HDL)-C ratio, low-density lipoprotein (LDL)-C, and triglycerides (TG) were significantly increased, and HDL-C was significantly decreased in CAPD patients compared with HD patients. FBG and FVIIc were significantly elevated in CAPD patients compared with controls or HD patients. T-PA activities were significantly higher in HD and CAPD patients than in controls. CAPD patients showed significantly higher PAI-1 activities than controls or HD patients. Significant positive correlations were found between FBG or FVIIc and TC, between FBG and LDL-C or TG, and between FVIIc and LDL-C in these patients. T-PA showed significant negative correlations with FBG, PAI-1, TC, LDL-C, and TG. There was a significant positive correlation between PAI-1 and TG and a significant negative correlation between PAI-1 and HDL-C. We conclude that CAPD patients may have a greater risk of CVD than do HD patients, and that coagulation and fibrinolytic activity are correlated with lipid disorders in these patients.

Ischemic stroke and the gene for angiotensin-converting enzyme in Japanese hypertensives

BACKGROUND

The ACE insertion/deletion (I/D) polymorphism is reported to be associated with myocardial infarction in both whites and Japanese. However, there have been no reports on the association of this polymorphism with stroke in each race. Furthermore, there are some racial differences in the demographics of cardiovascular disease. In Japanese, stroke (especially that which occurs in preexisting hypertension) is more common and coronary artery disease much less common than in whites. We propose that the ACE I/D polymorphism might be associated with hypertensive cerebrovascular disease in Japanese.

METHODS AND RESULTS

To study the association between the ACE I/D polymorphism and hypertensive cerebrovascular disease, we identified the ACE I/D genotype in 228 hypertensive and 104 normotensive Japanese subjects. Compared with its frequency (0.31) in the 90 hypertensives without lacunae detected by magnetic resonance imaging, the ACE*D allele frequency was significantly higher (0.47; P<.001) in the 138 hypertensives with silent or clinically overt ischemic stroke, whereas there was no significant difference between its frequency in hypertensives without lacunae and in 104 normotensive control subjects (0.34). The positive association between the ACE I/D genotype and ischemic stroke in hypertensive patients was independent of other risk factors.

CONCLUSIONS

We found a positive association between the ACE*D allele and ischemic stroke in Japanese hypertensives in our study. The ACE*D allele may be an independent risk factor for the development of cerebrovascular disease in hypertensive patients.

Suppression of plasma-activated factor VII levels by warfarin therapy

To investigate the effect of warfarin treatment on the early phase of tissue factor-induced coagulation, we measured plasma-activated factor VII (factor VIIa) levels by a direct fluorogenic assay in 74 cardiovascular disease patients on long-term oral anticoagulation. We divided the patients into three groups based on the international normalized ratio (INR). In the patients with INR ranges of < 1.7 and 1.7 to 2.5, factor VIIa levels were 42% and 61% lower, respectively, than in age- and sex-matched controls. Factor VII coagulant activity (factor VIIc), factor VII antigen (factor VIIag), protein C, and factor X levels were also reduced to a similar extent in both groups. However, in patients with an INR > 2.5, the factor VIIa level was not decreased compared with that at an INR of 1.7 to 2.5, although the factor VIIc, factor VIIag, factor X, and protein C levels were all decreased further. Although the precise relation between the reduction of factor VIIa levels and the increase of INR requires appropriately designed long-term clinical trials, our data suggest that an INR range of 1.7 to 2.5 is sufficient for the suppression of factor VIIa. During the long-term follow-up of three patients with congenital antithrombin III or protein C deficiency, the factor VIIa level was more responsive to changes in the warfarin dose than the INR, and there were generally no corresponding changes of the thrombin-antithrombin III complex (TAT) level. However, one patient showed a transient marked increase of factor VIIa during the discontinuation of warfarin that was accompanied by an increase in TAT. Based on these findings, factor VIIa could be useful for monitoring both hypercoagulable and hypocoagulable states.

Hypercoagulable state under low-intensity warfarin anticoagulation assessed with hemostatic markers in cardiac disorders

The hemostatic condition under low-intensity anticoagulation in cardiac disorders is not fully elucidated. The aim of this study was to ascertain whether hemostatic molecular markers are a useful assessment for anticoagulation to detect the hypercoagulable state. A hematologic study was performed in 75 outpatients, without thromboembolic episodes, treated with low-intensity anticoagulation (average international normalized ratio [INR] 1.72) because of potential cardiac sources of arterial emboli, and in 40 age-matched control subjects. The average level of thrombin-antithrombin III complex (TAT) was significantly lower in patients than in control subjects (p = 0.005), and the mean value of D-dimer was not statistically different between patients and control subjects. Although TAT correlated moderately with D-dimer (r = 0.45, p = 0.0001), INR did not correlate with TAT or D-dimer. Elevated TAT > 3.0 ng/ml and/or D-dimer S 150 ng/ml were observed in 15 patients (20.0%), whereas the remaining 60 patients (80.0%) had no obvious increase in the level of TAT or D-dimer at overall INR. Antithrombin III activity did not correlate significantly with INR, but protein C activity and free protein S antigen showed a significant negative relation to INR (r = 0.82, r = 0.62, respectively, p = 0.0001). Low-intensity anticoagulation was sufficient to reduce coagulation and subsequent fibrinolytic activation in cardiac disorders, but may not be sufficient in some patients with elevated TAT or D-dimer concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluorogenic assay of activated factor VII. Plasma factor VIIa levels in relation to arterial cardiovascular diseases in Japanese

Factor VII (FVII) plays an important role in initiation of the tissue factor-induced coagulation pathway. An increase in FVII coagulant activity (FVIIc) has been proposed as an independent risk factor for coronary artery disease. However, it remains uncertain whether high FVIIc levels are due to an increase in the activation of FVII or an increase in the concentration of FVII mass. We developed a new fluorogenic assay for plasma activated FVII (FVIIa) that used soluble tissue factor. The sensitivity of this assay ranged from 0.2 to 1000 ng FVIIa per milliliter of plasma. Plasma FVIIa levels were measured in 110 healthy subjects and 93 patients with hypertension, diabetes mellitus, and/or cardiovascular disease. The mean plasma FVIIa level in healthy Japanese individuals was 2.5 ng/mL, which was lower than that in Western subjects. Gel filtration analysis showed that most of the circulating FVIIa was in a free form, and binding of FVIIa to tissue factor in plasma was not detected. Aging increased both the FVIIa level and FVII mass, whereas menopause increased mainly the FVII mass. Elderly patients with arterial cardiovascular diseases showed increases in plasma FVIIa levels and FVIIa to FVII antigen (FVII:Ag) ratios. Among the elderly, arterial cardiovascular disease was more common in a high-FVIIa than a low-FVIIa group. Plasma FVIIa levels were not correlated with serum levels of total cholesterol or triglycerides. The FVIIa level and the FVIIa-to-FVII:Ag ratio were positively correlated with fibrinogen level and negatively correlated with body mass index and serum albumin level in the elderly. In conclusion, aging, cardiovascular disease, and malnutrition increased plasma FVIIa levels. FVIIa levels were not correlated with lipid levels or hepatic synthesis, suggesting that FVIIa may be an independent risk factor for cardiovascular disease.

Hematologic abnormalities occur in both cortical and lacunar infarction

BACKGROUND AND PURPOSE

Primary hematologic abnormalities are a rare but established cause of ischemic stroke. In addition, activation of hemostatic parameters is often present during the acute phase of stroke. However, it is uncertain whether these abnormalities occur in both cortical and lacunar infarction; this study aimed to further assess this issue.

METHODS

Hematologic parameters (prothrombin, activated partial thromboplastin, thrombin clotting, and euglobulin lysis times; and fibrinogen, fibrinopeptide A, antithrombin III, protein C, protein S, and plasminogen levels) were measured in 19 patients within 48 hours of the onset of acute cerebral infarction. These patients included 10 with cortical infarcts and 9 with lacunar infarcts, as determined by standard clinical and radiological criteria.

RESULTS

Five patients with lacunar infarction and 7 patients with cortical infarction demonstrated raised fibrinopeptide A levels, indicating enhanced thrombin activity. Fibrinolysis, assessed by the euglobulin lysis time, was impaired in 6 of 9 patients with lacunar infarction and in 2 of 10 patients with cortical infarction. Lupus anticoagulants were detected in 3 patients with lacunar infarction and in 1 patient with cortical infarction. Three patients in each group displayed decreased antithrombin III function, and 1 patient with a lacunar infarction had a low protein C level.

CONCLUSIONS

Primary hematologic disorders and secondary hemostatic derangements may occur in patients with either cortical or lacunar infarction.

Fibrinogen and the albumin-globulin ratio in recurrent stroke

BACKGROUND AND PURPOSE

In following patients initially recruited for a cross-sectional study of blood viscosity in ischemic cerebrovascular disease, it was noted that those having a low albumin-globulin ratio appeared to experience the majority of subsequent vascular events. Accordingly, a prospective study in which subjects were assigned to a high or low albumin-globulin cohort was undertaken to examine the relation between a low albumin-globulin ratio, the presence of clinical risk factors for stroke, and the occurrence of subsequent stroke, myocardial infarction, or vascular death.

METHODS

Three groups of subjects were followed for an average of 1.5 +/- 0.8 years to ascertain vascular end points. Group 1 consisted of 126 patients with acute ischemic stroke; group 2 included 109 subjects matched with group 1 for age, medications, and recognized clinical risk factors for stroke; and group 3 was composed of 84 healthy volunteers, matched for age with groups 1 and 2. The median albumin-globulin ratio for group 1 at enrollment, 1.45, was used to dichotomize patients into two cohorts: all subjects with an albumin-globulin ratio of 1.45 or less were assigned to the "low" albumin-globulin cohort; those whose ratio was greater than 1.45 were assigned to the "high" albumin-globulin cohort. The occurrence of vascular end points was verified during subsequent hospitalizations and outpatient clinic visits and by telephone interviews of patients and providers.

RESULTS

A total of 51 vascular events occurred, including 39 in group 1, 8 in group 2, and 4 in group 3. Subjects in either group 1 or 2 who were in the low albumin-globulin cohort had at least double the risk for a subsequent vascular event compared with their counterparts in the high albumin-globulin cohort (P < .01 and P < .03, respectively). In comparison with the high albumin-globulin cohort, significantly more patients in the low albumin-globulin cohort in group 1 had a history of prior stroke (P < .03). When groups 1 and 2 were combined, both a low albumin-globulin ratio and diabetes had a significant independent association with increased risk for subsequent vascular events in a Cox proportional-hazards model (P < .01 and P < .03, respectively).

CONCLUSIONS

The results of this study indicate that significantly increased risk for subsequent vascular events in stroke patients and in subjects with clinical risk factors for stroke is associated with a shift in the concentrations of blood proteins to a prothrombotic environment characterized by lower levels of albumin and an increased concentration of globulins and fibrinogen.

Markers of a hypercoagulable state following acute ischemic stroke

BACKGROUND AND PURPOSE

The nature of hematologic disorders in different stroke subtypes remains uncertain. The purpose of this study was to clarify the differences in the coagulation and fibrinolytic activities among ischemic stroke subtypes.

METHODS

We performed sequential measurements of hematologic parameters in 21 patients with acute cardioembolic stroke, 10 patients with atherothrombotic stroke, 23 patients with lacunar stroke, and 20 age-matched controls.

RESULTS

A marked elevation of plasma concentrations of the thrombin-antithrombin III complex and crosslinked D-dimer was observed only in cardioembolic stroke within 48 hours of onset (p less than 0.01), persisting for one month with a gradual decline. In atherothrombotic stroke, however, the level of crosslinked D-dimer was not elevated at the onset, but increased seven days after onset (p less than 0.01). No significant changes in these marker levels were observed in lacunar stroke.

CONCLUSIONS

Our findings suggest that the nature of altered coagulation and fibrinolysis are different in various subtypes of ischemic stroke, and that an assessment of these hematologic parameters may be useful for the early classification of these subtypes.

Activation of coagulation in acute cardioembolic stroke

The hematologic disorders in patients with acute cardioembolic stroke are not fully understood, and no reliable measures are available to identify patients at high risk for recurrent embolism. We analyzed coagulation and fibrinolytic functions in 22 patients with cardiogenic cerebral embolism less than or equal to 24 hours after onset and in 25 age-matched controls. The levels of antithrombin III, protein C, and alpha 2-plasmin inhibitor were significantly lower in the patients than in the controls (p less than 0.001, 0.02, and 0.05, respectively). In contrast, the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer were markedly higher in the patients than in the controls (p less than 0.01 and 0.001, respectively). At the time of admission, the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer in the eight patients at high risk for recurrent embolization (one with prodromal embolism, three with intracardiac thrombi, and four with recurrent embolization) were 2.8 and 3.5 times, respectively, higher than those in the 14 patients without recurrence or thrombus formation. The lowest concentration of crosslinked D-dimer in the eight patients at high risk for recurrent embolization was 600 ng/ml on admission. Our results suggest that patients with acute cardioembolic stroke have various degrees of consumption coagulopathy and that the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer can be useful indicators of those who are prone to recurrent embolization during this stage.