Abstract
Aims: The objective of our study was to assess the effects of orthostatic challenge on the coagulation system in patients with a history of thromboembolic events and to assess how they compared with age-matched healthy controls.Methods: Twenty-two patients with histories of ischemic stroke and 22 healthy age-matched controls performed a sit-to-stand test. Blood was collected prior to- and at the end of- standing in the upright position for 6 min. Hemostatic profiling was performed by determining thrombelastometry and calibrated automated thrombogram values, indices of thrombin generation, standard coagulation times, markers of endothelial activation, plasma levels of coagulation factors and copeptin, and hematocrit.Results: Orthostatic challenge caused a significant endothelial and coagulation activation in patients (Group 1) and healthy controls (Group 2): Plasma levels of prothrombin fragment F1+2 were increased by approximately 35% and thrombin/antithrombin-complex (TAT) increased 5-fold. Several coagulation variables were significantly altered in Group 1 but not in Group 2: Coagulation times (CTs) were significantly shortened and alpha angles, peak rate of thrombin generation (VELINDEX), tissue factor (TF) and copeptin plasma levels were significantly increased (comparison between standing and baseline). Moreover, the shortening of CTs and the rise of copeptin plasma levels were significantly higher in Group 1 vs. Group 2 (comparison between groups).Conclusion: The coagulation system of patients with a history of ischemic stroke can be more easily shifted toward a hypercoagulable state than that of healthy controls. Attentive and long-term anticoagulant treatment is essential to keep patients from recurrence of vascular events.
Highlights
Several studies have reported that an orthostatic challenge activates the coagulation system
A significantly higher number of patients who had recovered from ischemic stroke were treated with antiplatelet
While the results from those studies were based on stationary standing periods that varied from 15 to 60 min, we observed that a short 6 min standing period leads to a significant activation of the coagulation system
Summary
Several studies have reported that an orthostatic challenge activates the coagulation system Both active and passive standing are associated with (i) pooling of blood in the legs, (ii) increased transmural pressure, (iii) increased shear stress, as well as (iv) endothelial activation in the lower extremities, associated with (v) release of procoagulant glycoproteins, e.g., Tissue Factor (TF) (Masoud et al, 2008; Cvirn et al, 2012; Haider et al, 2013). All these studies have been performed in healthy young controls. Orthostatic challenge-induced coagulation activation might constitute a problem for patients at an already elevated risk for vascular events, for example, ischemic stroke
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