GUSTO IV: expanding therapeutic options in acute coronary syndromes

Abciximab inhibits procoagulant activity but not the release reaction upon collagen- or clot-adherent platelets

In addition to inhibiting platelet (plt) aggregation abciximab, a glycoprotein (GP) IIb/IIIa antagonist, reduces coagulation in blood or platelet-rich plasma. We assessed the effects of abciximab (10 micro g mL(-1)) on adhesion-dependent procoagulant activity (PCA) of plt upon: (i) collagen to model initial adhesion; or (ii) plasma clot or fibrin to model a preformed thrombus with retained thrombin activity. In a two-stage assay gel-filtered plt (GFP) first adhered on collagen, plasma clot, or fibrin, and plt activation was traced with platelet factor 4 (PF 4) release. Second, PCA was measured on adherent plt (i) by soluble prothrombin fragments (F1 + 2); and (ii) chromogenically by adding defibrinated plasma and thromboplastin. Abciximab inhibited aggregation upon collagen-adherent plt both in the absence and presence of plasma. In contrast, without plasma abciximab enhanced plt deposition to fibrin surfaces depending on thrombin generation and fibrin polymerization. However, abciximab reduced PCA and generation of F1 + 2 on adherent plt surface-independently by 35%, whereas PF 4 release persisted. Also, a GP Ib inhibitor, mAb SZ2, attenuated PCA by 40% alone, and by 65% together with abciximab, leaving 35% of PCA unaltered. Abciximab decreased generation of new thrombin on both collagen- and clot-adherent plt. However, abciximab did not inhibit alpha-granule release, suggesting distinct pathways for PCA and release reaction. Deposition of isolated plt on clots in the presence of abciximab was dependent on thrombin and polymerizing plt-derived fibrin(ogen). Due to local consumption of natural anticoagulants adjacent to a preformed thrombus the antithrombotic effect of abciximab benefits from additional inhibition of thrombin.

Pharmacologic reperfusion therapy for acute myocardial infarction

Acute myocardial infarction (MI) remains a significant problem in terms of morbidity, mortality and healthcare costs. Pharmacologic reperfusion therapies for MI are becoming increasingly complex. This review therefore places contemporary pharmacologic MI developments into perspective. An historical overview of pharmacologic reperfusion therapy for MI is provided, followed by an analysis of current limitations, treatment options, and present and likely future pharmacologic therapies. Adjunctive percutaneous and other treatments are also discussed, to clarify what is becoming a rapidly changing field.

Pharmaceutical thrombosis prevention in cardiovascular disease

Cardiovascular diseases are a leading cause of morbidity and mortality in modern society. As a result of this, great efforts have been made to establish regimens for prophylaxis and treatment of such disorders. Pharmacological intervention is also a prerequisite for the success of other therapeutic approaches, e.g. coronary angioplasty. Prevention of platelet aggregation is a goal that can be achieved by counteracting various receptors on the platelet surface. The main attentions for such interventions are focused on inhibiting the glycoprotein IIb/IIIa receptor. So far, they are limited to intravenous usage. Adenosine diphosphate receptor inhibitors are available for intravenous and oral usage. Their effect is, at least partly, also exerted via the counteraction of adenosine diphosphate-mediated activation of the glycoprotein IIb/IIIa complex. An oral direct thrombin inhibitor is under clinical evaluation. This review focuses on atherothrombotic disorders, but recent advances within new fields of anticoagulation (i.e., treatment of severe septic shock and a novel approach to prevent thromboembolic disorder during surgery) should not be overlooked.