Copyright © 1995 by the European Society of Cardiology.
© 1995 The European Scociety of Cardiology
Bleeding risks, risk factors and management of bleeding complications after treatment with anticoagulants, specific antithrombins, thrombolytics IIb-IIIa receptor blockers
* Department of Medicine, The University of Alberta Edmonton, Alberta, Canada
Division of Clinical Hematology and Medical Oncology, The University of Alberta Edmonton, Alberta, Canada
Correspondence: Dr P. W. Armstrong. Chair, Department of Medicine, 2F130 WMC, University of Alberta, Edmonton, Alberta, Canada T6G 2R7.
Assessment of the risks of new antithrombotic therapies is best undertaken by evaluating risk factors for bleeding in individual patients, and risks associated with specific antithrombotic agents. This forms the basis for the development of a management strategy for major bleeding complications. Patient-related risk factors for bleeding with oral anticoagulants include:trauma, invasive procedures, history of bleeding disorder, high anticoagulant intensity, concomitant use of antiplatelet drugs, presence of underlying severe disease, advanced age, and prior history of cerebrovascular accident, or gastrointestinal bleeding. Weight-adjusted and other nomograms are more successful in achieving a balance between therapeutic effect and safety with intravenous heparin. The most important complication of thrombolytic therapy is intracranial haemorrhage, and the risks increase with age >65 years, weight under 70 k, hypertension on admission and the use of tissue plasminogen activator: this profile is helpful in assessing risk-benefit ratio amongst individual patients Recent experience with the experimental use of antithrombin agents such as hirudin, indicates a delicate dose-response relationship as it relates to the risk of cerebral haemorrhage, when used in conjunction with thrombolytic agents. A definitive answer regarding the role of hirudin and the balance of safety and efficacy awaits completion of ongoing trials. Novel IIb/IIIa platelet inhibitors appear to offer a significant therapeutic advance: major bleeding is variable and depends in part on the use of concomitant procedures, and heparin therapy.
It is important to identify the source and severity of bleeding with the use of antithrombotic therapy and its haemodynamic consequences in constructing a management plan. Well developed treatment algorithms for patients with severe bleeding exist, and although laboratory testing may be helpful, it is on balance of marginal benefit since patients usually require urgent therapy. Future investigation promises more readily available, rapid and specific laboratory testing, and newer antithrombotic agents that are easier to administer and monitor. Molecular targeting with fusion proteins that attract to a specific antigen, thereby delivering more effective and safe therapy, offer new promise.
Key Words: Bleeding • risks • anticoagulants • antithrombins • thrombolytics • platelet • inhibitors