Thromb Haemostasis
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Dabigatran is an oral direct thrombin inhibitor that does not require routine laboratory monitoring. However, an assessment of its anticoagulant effect in certain clinical settings is desirable. We examined the relationship between dabigatran levels, as determined by the Hemoclot thrombin inhibitor assay (HTI), the thrombin time (TT) and the activated partial thromboplastin time (aPTT) using different reagents. ⋯ The TT was sensitive to the presence of dabigatran with a level of 60 ng/ml resulting in a TT > 300 s. In conclusion, the aPTT demonstrated a modest correlation with the dabigatran level and was less responsive with supra-therapeutic levels. aPTT reagents differed in their responsiveness, suggesting individual laboratories must determine their own therapeutic range for their aPTT reagent. The TT is too sensitive to quantify dabigatran levels, but a normal TT suggests minimal or no plasma dabigatran.
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Recent European Society of Cardiology (ESC) Guidelines declare superiority of prasugrel and ticagrelor over clopidogrel in non-ST segment elevation myocardial infarction (NSTEMI) and STEMI patients with acute coronary syndromes (ACS). The recommendations for NSTEMI and especially STEMI are based on a subgroup analyses yielded from a single trial with either prasugrel (TRITON), or ticagrelor (PLATO). In contrast, the United States (US) Guidelines present a more balanced, conservative, and evidence-based outlook suggesting no proven extra benefit of one P2Y12 antagonist over the other(s). ⋯ Some of the pivotal data with regard to the newer P2Y12 inhibitors (prasugrel and ticagrelor) on event definition, adjudication, questionable efficacy, and serious safety concerns were ignored by the European Task Force Members, while the other "beneficial" findings were exaggerated to a disproportional extent. We conclude that current ESC Guidelines, with regard to their recommendation of superiority of prasugrel or ticagrelor over clopidogrel, in contrast to the US, are overoptimistic, and not evidence based. Low clinical utilisation of prasugrel and especially ticagrelor worldwide in general, and Europe in particular suggests mismatch of prescription habits with issued ESC recommendations.
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Rivaroxaban is an oral, direct factor Xa inhibitor for the management of thromboembolic disorders. Despite its short half-life, the ability to reverse rivaroxaban anticoagulation could be beneficial in life-threatening emergencies. The potential of prothrombin complex concentrate (PCC; Beriplex®), activated PCC (aPCC; FEIBA®) or recombinant activated factor VII (rFVIIa; NovoSeven®) to reverse rivaroxaban in rats and baboons was investigated. ⋯ Prolongation of prothrombin time was reduced by PCC, aPCC and rFVIIa in both species. Rivaroxaban reduced thrombin-antithrombin levels; application of PCC and aPCC, but not rFVIIa, increased these levels. In conclusion, PCC, aPCC or rFVIIa have the potential to reverse the anticoagulant and anti-haemostatic effects of rivaroxaban.
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The development of thrombosis in polycythaemia vera (PV) involves multifactorial processes including pathological activation of blood cells. Release of microparticles (MPs) by activated cells in diseases is associated with thrombotic risk, but relatively few data are available in PV. The aim of the present study was to investigate the increase in MP release and exposure of phosphatidylserine (PS) on the outer membrane of MP-origin cells in patients with PV, and to analyse their procoagulant activity (PCA). ⋯ Moreover, lactadherin competed factor V and VIII to PS and inhibited about 90% of the detected PCA in a dose-response manner while anti-TF antibody did no significant inhibition. Treatment with hydroxyurea is associated with a decrease in PS exposure and lactadherin+ MP release of erythrocytes/platelets. Our data demonstrate that PV patients are characterised by increased circulating procoagulant MPs and PS exposing erythrocytes/platelets, which could contribute to the hypercoagulable state in these patients.