Changes of von Willebrand factor and antithrombin III levels in acute stroke: difference between thrombotic and haemorrhagic stroke

[Prognostic value of endothelial dysfunction and von Willebrand factor in acute and chronic hemispheric intracerebral hemorrhage]

AIM

To study the changes in endothelial dysfunction and von Willebrand factor activity in acute and chronic stages of hemispheric intracerebral hemorrhage (ICH) and their influence on clinical severity and functional recovery.

MATERIAL AND METHODS

Fifty patients with hemispheric ICH, aged 61.6±11.2 years, and 30 patients with AH, aged 59.6±6.2 years, (comparison group) were examined. Patients with ICH were examined on admission, 6-8^th, 13-15^th days, and 11.1±0.9 months after stroke onset. Patients with arterial hypertension (AH) were examined on admission. Changes in NIHSS, Glasgow coma scale, and modified Rankin scale were studied. Restocetin induced platelet aggregation (RIPA) was assessed by optical aggregometry (BIOLA LA230-2 AGGRWB) in modification by G. Born and Z. Gabbasov. von Willebrand factor (vWF) activity was examined as described by J. Olson.

RESULTS

RIPA was significantly higher in acute ICH compared to chronic ICH, AH and reference values. RIPA values were negatively correlated with hematoma volume and midline shift (r≥ -0.308, p≤0.035). vWF activity was significantly higher in ICH patients than in AH and reference values. Patients with AH also had significantly higher vWF activity than reference values. In acute ICH, vWF activity steadily increased reaching maximal values by 13-15^th day. In chronic ICH, vWF activity decreased compared to the acute phase, but still remained higher than in AH patients or reference values. In acute phase, 1% increment in vWF values resulted in 0.5% increase in the risk of death during the follow-up period (95% CI 1.001-1.008, p=0.007).

CONCLUSION

Endothelial dysfunction assessed by vWF activity increases during the acute hemispheric ICH and remains elevated in the chronic stage. vWF activity may be used as a marker in assessing stroke outcome and prognosis.

Von Willebrand factor and ADAMTS13 in arterial thrombosis: a systematic review and meta-analysis

Von Willebrand Factor (VWF) plays an important role in hemostasis by mediating platelet adhesion and aggregation. Ultralarge VWF multimers are cleaved by ADAMTS13 in smaller, less procoagulant forms. An association between high VWF levels and cardiovascular disease has frequently been reported, and more recently also an association has been observed between low ADAMTS13 levels and arterial thrombosis. We reviewed the current literature and performed meta-analyses on the relationship between both VWF and ADAMTS13 with arterial thrombosis. Most studies showed an association between high VWF levels and arterial thrombosis. It remains unclear whether ADAMTS13 is a causal independent risk factor because the association between low ADAMTS13 and arterial thrombosis is so far only shown in case-control studies. Prospective studies are awaited. A causal role for ADAMTS13 is supported by mice studies of cerebral infarction where the infusion of recombinant human ADAMTS13 reduced the infarct size.

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.

Increased von Willebrand factor in acute stroke patients with atrial fibrillation

Plasma level of von Willebrand factor (vWF) is a useful marker not only for endothelial dysfunction, but also for left atrial thrombogenesis. We measured plasma levels of vWF antigen and other coagulation and fibrinolysis markers in 183 consecutive patients with acute ischemic stroke and compared these data between patients with and without atrial fibrillation (AF). vWF correlated with severity, outcome, and infarct size and were significantly higher in the AF group than in the non-AF group. The positive correlations of vWF with plasmin-alpha2 plasmin inhibitor complex and soluble fibrin monomer complex, and higher levels of vWF in patients with than without spontaneous echo contrast, indicate thrombogenesis in the left atrium. Plasma levels of vWF may reflect thrombogenesis in patients with AF.

Sequential alterations in haemorheology, endothelial dysfunction, platelet activation and thrombogenesis in relation to prognosis following acute stroke: The West Birmingham Stroke Project

Abnormalities of haemorheology (plasma viscosity, fibrinogen), endothelial function [von Willebrand factor (vWf)], platelet activation (soluble P-selectin) and thrombogenesis [plasminogen activator inhibitor (PAI), and fibrin D-dimer] are common in cardiovascular disease. We investigated changes in these markers in 86 patients (58 males) presenting with acute stroke (all age < 75 years, with ictus < 12 h), and sequential changes at six time points (baseline on admission, 48 h, 1 week, 2 weeks, 3 months and 6 months following the onset of stroke). Baseline plasma viscosity, haematocrit, fibrinogen, vWf, PAI, soluble P-selectin and fibrin D-dimer levels were increased in the acute stroke patients compared with 35 age-matched and sex-matched controls. Following admission, there were significant increases in haematocrit at 2 weeks, vWf at 48 h and 1 week, fibrinogen at 1 week, PAI at 48 h and 1 and 2 weeks, soluble P-selectin at 48 h, and fibrin D-dimer at 48 h and 1 week following admission. Using univariate 'time to event' analysis, high (> median) mean age (log-rank test, P = 0.0262), diastolic blood pressure (P = 0.01), haematocrit (P = 0.0234), PAI-1 (P = 0.0066) and fibrin D-dimer levels (P = 0.0356) were associated with a shortened event-free survival. Using a multivariate Cox survival analysis, only PAI-1 levels remained an independent predictor of survival (P = 0.0349). We conclude that acute stroke patients have marked baseline abnormalities of haemorheology, endothelial disturbance, thrombogenesis, platelet activation and abnormal fibrinolysis, with further changes over the subsequent follow-up period. Abnormal thrombogenesis and fibrinolysis may significantly influence survival in patients with acute stroke. These changes may have potential implications for the pathogenesis of stroke and its complications, although the possibility remains that we are documenting an acute phase response that previous studies, which included stroke patients with a wide time range since ictus onset, have neglected to consider.

Sequential changes in von Willebrand factor and soluble thrombomodulin in acute ischemic stroke

The purposes of the present study were to investigate sequential changes in plasma von Willebrand factor (vWf) activities and serum soluble thrombomodulin (sTM) concentrations, compared with white blood cell (WBC) counts, and to disclose the different roles of vWf and sTM in acute ischemic stroke. Forty-three acute ischemic stroke patients admitted to our hospital within 48 hours from onset were enrolled. Plasma vWf activities, serum sTM concentrations, and WBC counts were measured at the acute stage and 1 and 6 months after admission. The time course study revealed that vWf activities increased more markedly 1 month after admission than at the acute stage. However, sTM concentrations were low at the acute stage and increased sequentially at 1 month (not significantly) and 6 months (significantly) after admission. In contrast, elevated WBC counts at the acute stage decreased significantly at 1 and 6 months after admission. Raised vWf activities 1 month after admission were suggested to occur through continuous endothelial dysfunction or repair and platelet activation, compared with the acute stage, and decreased sTM at the acute stage through down-regulation of sTM synthesis by acute inflammatory response after acute ischemic stroke, compared with the chronic stage.

Abnormal haemorheology, endothelial function and thrombogenesis in relation to hypertension in acute (ictus < 12 h) stroke patients: the West Birmingham Stroke Project

While the blood vessels are exposed to high pressures in hypertension, the main complications of hypertension (stroke and myocardial infarction) are paradoxically thrombotic rather than haemorrhagic. To investigate abnormalities of haemorheology (plasma viscosity, fibrinogen), endothelial dysfunction (von Willebrand factor), platelet activation (soluble P-selectin) and thrombogenesis (plasminogen activator inhibitor and fibrin D-dimer) in stroke and the effects of concurrent hypertension, we studied 86 consecutive patients (58 male, 28 female) aged < 75 years (mean age +/- SD, 64.2 +/- 9.2 years) with acute stroke (ictus < 12 h). Baseline blood tests on admission were compared with 46 'hospital controls' (patients with uncomplicated essential hypertension; mean age +/- SD, 65.9 +/- 3.8 years) and 24 healthy normotensive controls (mean age +/- SD, 65 +/- 14.0 years). Further comparisons were made between stroke patients with hypertension (systolic blood pressure > 160 mmHg and/or diastolic > 90 mmHg) on admission and those without hypertension. Mean plasma viscosity (one-way analysis of variance, P = 0.026) and fibrinogen levels (P = 0.016) were significantly higher in stroke patients and hospital controls, when compared with healthy controls. The von Willebrand factor, plasminogen activator inhibitor soluble P-selectin and fibrin D-dimer levels were highest in the acute stroke patients, intermediate in hospital controls and lowest in healthy controls (all P < or = 0.001). There were no significant differences in measured indices of haemorheology, endothelial dysfunction and thrombogenesis between the three stroke pathological subtypes (ischaemic/thrombotic, haemorrhagic or transient ischaemic attack). There were also no significant differences in the measured parameters for stroke patients with or without systolic blood pressure > 160 mmHg or diastolic blood pressures > 90 mmHg using clinical (manual) readings or mean daytime or night-time ambulatory blood pressure monitoring recordings. There were no statistically significant differences between the measured parameters on admission and at 3 months follow-up in 26 patients (all P = not significant). Plasma viscosity was significantly correlated with mean daytime systolic blood pressure (r = 0.314, P = 0.021) and mean night-time systolic blood pressure (r = 0.309, P = 0.025). This study of hypertension and haemostasis in acute stroke has demonstrated clear abnormalities of haemorheology, endothelial dysfunction, platelet activation and thrombogenesis, which do not appear to be affected by the height of the blood pressure or the presence of hypertension. This is despite the known hypercoagulable state found in hypertension and the relationship of haemostatic abnormalities to vascular complications.

Hypercoagulable states

The hypercoagulable state has been defined as the potential to develop thrombosis in association with hereditary and noninherited genetic mutations and acquired disorders. It is a condition that places an individual at risk for, but does not in itself inevitably lead to, thrombosis. The focus of this article is understanding mechanisms in the hypercoagulable state that enhance and maintain the production of thrombin in circulating blood while preventing its progression to thrombosis. These mechanisms include reactions that produce thrombin from prothrombin, feedback loop mechanisms that affect the rate of thrombin production from prothrombin and the inactivation of thrombin in blood. The fibrinolytic system is involved in clot lysis but not in thrombin production and inactivation.

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.

von Willebrand factor and its relevance to cardiovascular disorders

In the past decade the importance of the vascular endothelium in cardiovascular pathophysiology has become more apparent. One substance that is synthesised by and stored in endothelial cells is von Willebrand factor (vWF). When released, vWF seems to mediate platelet aggregation and adhesion to the vascular endothelium. Because the release of vWF is increased when endothelial cells are damaged, vWF has been proposed as an indicator of endothelial disturbance or dysfunction. The availability of such an index of endothelial dysfunction may have clinical value, because measurement of such a marker can be a non-invasive way of assisting in diagnosis or as an indicator of disease progression. The known association between vWF, thrombogenesis, and atherosclerotic vascular disease also suggests that high concentrations of vWF may be an indirect indicator of atherosclerosis and/or thrombosis. In addition, high vWF concentrations have prognostic implications in patients with ischaemic heart disease and peripheral vascular disease.