Optimizing adjunctive antithrombotic therapy in the treatment of acute myocardial infarction: A role for low‐molecular‐weight heparin

Abstract

Summary:Thrombotic complications account for a large proportion of in-hospital deaths from acute myocardial infarction (MI). Although thrombolytic therapy has greatly improved clinical outcomes following MI, thrombin released during clot lysis has a prothrombotic effect, and the thrombolytic agents themselves may directly activate platelets. Antithrombotic therapy as an adjunct to thrombolysis improves the speed and extent of artery recanalization and reduces the incidence of secondary ischemic complications. The current treatment standard is unfractionated heparin (UFH) administered intravenously for 24-48 h. However, UFH has not been unequivocally shown to improve outcomes in large-scale, randomized clinical trials, and shows no evidence of benefit when used as an adjunct to streptokinase-based thrombolysis. Unfractionated heparin also has several clinical and practical disadvantages, such as the need for coagulation monitoring, difficulties attaining a stable and reliable anticoagulant effect, and the risk of hemorrhagic side effects. Low-molecular-weight heparin (LMWH) represents a safe and effective alternative antithrombotic therapy, with a stable and predictable anticoagulant effect, potential for use in combination with either fibrin-specific or streptokinasebased thrombolysis, no need for anticoagulation monitoring, and a low risk of hemorrhagic and other hepar in-related complications. Several randomized clinical trials have shown that adjunctive LMWH is at least as effective as UFH in the acute phase of MI, is associated with fewer in-hospital recurrent ischemic events, and has an acceptable safety profile.

Passivating Injured Endothelium with Kinexins in Thrombolytic Therapy

“…8 Increased thrombin generation, fibrin formation and platelet aggregation might contribute to delayed recanalization and early re-occlusion. 10,11 It has been acknowledged that adjunctive anticoagulation using heparin with fibrin-specific fibrinolysis may improve the speed and extent of arterial recanalization in treatment of acute myocardial infarction 12,13 or acute ischaemic stroke 14 at a cost of severe haemorrhagic adverse effects. However, the re-occlusion rate ranged 10 to 20% and was not influenced by concomitant heparin administration, suggesting that antithrombin-dependent anticoagulants were not completely effective against further thrombus formation.…”