Activation of the inflammation, coagulation, and fibrinolysis systems, without influence of abciximab infusion in patients with non-ST–elevation acute coronary syndromes treated with dalteparin : a GUSTO IV substudy

• BackgroundIn acute coronary syndromes, the inflammation and the coagulation systems are activated, implying an impaired outcome. In addition to platelet inhibition, recent evidence suggests that the glycoprotein IIb/IIIa receptor inhibitor abciximab attenuates inflammation and coagulation activity.MethodsThe Swedish Global Utilization of Strategies To open Occluded arteries-IV (GUSTO-IV) substudy included 404 patients with non-ST–elevation acute coronary syndromes. In addition to aspirin and dalteparin, all patients were randomized to receive abciximab infusion for 24 hours or 48 hours or corresponding placebo without early coronary revascularization. Plasma samples were obtained at baseline and 24, 48, and 72 hours.ResultsThe median levels of the coagulation markers thrombin/antithrombin complex and soluble fibrin increased significantly from 3.1 to 3.7 ug/L (baseline to peak; P <.001) and from 20 to 23 nmol/L (P <.001), respectively. The fibrinolysis marker, tissue plasminogen-activator, also increased its median levels, from 11.7 to 17.5 ug/L (P <.001), whereas the median level of plasminogen-activator-inhibitor was unchanged. The inflammatory markers interleukin-6, C-reactive protein, and fibrinogen also increased their median levels (5.4–7.8 ng/L, P <.001; 4.4–8.7 mg/L, P <.001; 3.3–3.9 g/L, P <.001). However, there were no differences in median levels or in changes of median levels of any marker at any point between the placebo group and any of the abciximab groups.ConclusionsIn non-ST–elevation acute coronary syndrome, there was a simultaneous activation of the inflammation, coagulation, and fibrinolysis systems, despite aspirin and dalteparin treatment. Prolonged treatment with abciximab had no influence of the activation of these systems.Unstable coronary artery disease (CAD) intricately involves inflammatory mediators in the development of an atherosclerotic plaque and in thrombus formation by platelet aggregation.1 Acute phase elevation of inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6), and fibrinogen are important predictors of the short- and long-term prognosis in unstable CAD.2, 3 and 4 Activation of the coagulation and fibrinolysis systems, as demonstrated with elevated markers of thrombin generation, thrombin activity, and fibrin turnover, also have been found in the acute phase of unstable CAD and are associated with an adverse outcome.5, 6 and 7 Glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors potently inhibit platelet aggregation and reduce the incidence of ischemic events in patients undergoing percutaneuos coronary interventions8, 9 and 10 and in patients with unstable CAD.11 The GP IIb/IIIa inhibitor abciximab, in addition to its antithrombotic effect, also suppresses the rise in levels of inflammatory markers after percutaneous coronary interventions.12 This anti-inflammatory effect might be related to abciximab's cross-reaction with other integrin receptors.13 Furthermore, by inhibiting platelet aggregation, abciximab might also attenuate the coagulation and fibrinolysis activation as shown in vitro and in vivo.14 and 15The Global Utilization of Strategies To Open occluded arteries in acute coronary syndromes (GUSTO IV-ACS) trial unexpectedly failed to show any benefit of abciximab treatment in a high risk ACS population not undergoing early coronary revascularization.16 In the GUSTO IV-ACS low-molecular weight heparin substudy,17 dalteparin was used as the anticoagulant. Dalteparin, which is an inhibitor of the coagulation cascade, mainly by inhibition of factor Xa and less of factor IIa, has previously been shown to reduce the generation and activity of thrombin in unstable coronary disease.18 There is evidence that a combination of abciximab and a low-molecular-weight heparin have additive effects on the lag-time to platelet aggregation,19 and there are several theoretical advantages with the combination treatment. There was still no significant reduction in clinical events with abciximab in combination with dalteparin.17 The aim of this Swedish substudy of GUSTO IV-ACS was to evaluate the influence of abciximab infusion on markers on inflammation, coagulation, and fibrinolysis in patients with unstable CAD treated with aspirin and subcutaneous dalteparin.

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