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Reactivation of the coagulation system: rationale for long-term antithrombotic treatment
1Department of Cardiology, Aker University Hospital, Oslo, Norway.
Insights
Combined aspirin and heparin reduce cardiac events, but heparin withdrawal increases short-term risk. Longer treatment duration may improve long-term outcomes for acute coronary syndromes.
Area of Science:
- Cardiology
- Thrombosis Research
- Vascular Medicine
Background:
- Acute coronary syndromes (ACS) stem from coronary artery thrombosis on disrupted atherosclerotic plaques.
- Thrombotic risk factors influence thrombus extent and duration, impacting ACS clinical presentation.
- Platelet activation and thrombin generation are key to the thrombotic response.
Purpose of the Study:
- To evaluate the efficacy of combined antiplatelet and anticoagulant therapy in ACS.
- To investigate the impact of heparin withdrawal on short-term and long-term cardiac event risk.
- To explore strategies for improving long-term clinical outcomes in ACS patients.
Main Methods:
- Review of clinical data on aspirin and heparin treatment in ACS.
- Analysis of event rates following heparin withdrawal versus aspirin monotherapy.
- Assessment of long-term outcomes with different antithrombotic strategies.
Main Results:
- Combined aspirin and heparin are more effective than monotherapy for acute risk reduction.
- Heparin withdrawal is linked to a transient increase in serious cardiac events.
- Long-term event rates are not significantly improved by acute-phase heparin or direct antithrombins.
Conclusions:
- Transient hypercoagulability post-heparin and ongoing thrombin generation contribute to event rebound.
- Extended combined antiplatelet and anticoagulant therapy may enhance long-term ACS outcomes.
- Treating until lesion healing or plaque stabilization could be beneficial.
Abstract:
Coronary artery thrombosis superimposed on a disrupted atherosclerotic plaque has emerged as the pivotal pathophysiologic event in acute coronary syndromes (i.e., unstable angina, myocardial infarction, and sudden death). The various clinical manifestations depend on the extent and duration of thrombus deposition, which are determined by several local and systemic thrombogenic risk factors. The thrombotic response to plaque disruption involves both platelet activation and thrombin generation. Accordingly, combined treatment with aspirin and heparin has proved more efficacious than either treatment alone in the risk reduction of serious cardiac events in patients with unstable angina or non-Q-wave infarction. However, withdrawal of heparin is, even after prolonged treatment, associated with an increased short-term risk of serious cardiac events relative to the risk in patients given only aspirin. Furthermore, the long-term relative event rate seems not to be influenced by administration of heparin or direct antithrombins in the acute phase. Both transient hypercoagulability associated with heparin withdrawal and continuous thrombin generation over a longer term related to the underlying disease may explain the rebound in clinical events. Longer duration of combined antiplatelet and anticoagulant treatments, e.g., until healing of the culprit lesion or even until stabilization of vulnerable, yet nondisrupted plaques, may improve long-term clinical outcome.