Description
The financial burden of thrombotic events in cardiovascular disease is enormous. Anticoagulant medication is advised for the treatment and secondary prevention of acute coronary syndrome as well as the prevention of thrombotic events in numerous cardiovascular disorders, such as stroke in atrial fibrillation. Present-day parenteral anticoagulants consist of fondaparinux, low-molecular-weight heparins (LMWHs), and unfractionated heparin. When admitted to the hospital, patients with acute coronary syndrome are typically given either unfractionated heparin or a low-molecular weight heparin (LMWH). Both treatments are equally effective in lowering the risk of death and myocardial infarction, although LMWHs may be safer and don't need to be monitored for blood clotting. Using fondaparinux reduces mortality from acute coronary syndrome considerably when compared to LMWHs or unfractionated heparin. However, long-term outpatient usage of parenteral medications is inconvenient. The only oral anticoagulants available at this time are vitamin K antagonists. A large unmet need exists for new convenient and well-tolerated oral anticoagulants that do not require routine monitoring.
Summary Listen
- Dr. Abishek discusses anticoagulants in the context of cardiovascular disease (CVD), defining CVD as diseases involving the heart and major vessels. Common examples include atherosclerotic coronary artery disease, pulmonary thromboembolism, aortic dissection, aortic aneurysm, peripheral vascular disease, and stroke. He emphasizes the importance of understanding fluid dynamics and clinical aspects for effective treatment.
- The talk delves into the history of understanding thrombosis, highlighting contributions from Hippocrates, William Harvey, and Virchow. Key concepts include the Virchow triad (stasis, hypercoagulability, endothelial injury) and the role of endothelium in thrombosis. Antithrombotic drugs are classified as antiplatelet, anticoagulant, and fibrinolytic agents, each targeting different stages of thrombus formation.
- Arterial thrombosis is primarily driven by platelet activation, requiring antiplatelet drugs, whereas venous thrombosis is associated with stasis and coagulation, necessitating anticoagulants. Atrial fibrillation, due to ineffective atrial contraction leading to blood stasis, also requires anticoagulants. Acute fibrin generation, as in acute ST-elevation myocardial infarction, calls for fibrinolytic agents.
- The discovery and mechanisms of action of heparin are discussed. Heparin acts by enhancing antithrombin activity, inhibiting factor 2a (thrombin) and factor 10a. However, its variable binding to plasma proteins affects predictability of action, requiring monitoring via aPTT. Heparin resistance, often seen in ICU patients due to inflammatory mediators, is addressed.
- Low molecular weight heparins (LMWHs) are discussed as smaller molecules primarily targeting Factor 10a. Warfarin, initially a rodenticide, inhibits vitamin K-dependent coagulation factors. Starting warfarin requires bridging with an injectable anticoagulant due to the initial prothrombotic effect caused by the early reduction in protein C and S. Specific scenarios where warfarin remains the preferred option are emphasized.
- Newer oral anticoagulants (NOACs) offer advantages like low bleeding risk and no need for routine INR monitoring. Management of anticoagulation around procedures involves balancing thrombotic and bleeding risks. Bridging strategies with heparin are often used. Specific considerations for pregnancy and anticoagulation are discussed, including the teratogenic effects of warfarin.
- Special scenarios, such as anticoagulation post-stroke, are addressed. Additionally, low platelet counts and their impact on antiplatelet therapy strategies are examined. Practical considerations such as peri-gastric bypass surgery drug absorption and drug interactions, including with PPIs, which can be used to reduce the rate of upper GI bleeds in patients taking oral anticoagulants, are discussed.
- The speaker concludes by addressing the management of patients who experience myocardial infarction while already on anticoagulation, underscoring the importance of assessing thrombotic and bleeding risks for optimal management of triple therapy. The Compass trial is highlighted for demonstrating the effectiveness of low-dose rivaroxaban with a single antiplatelet agent in high-risk patients.
Sample Certificate
About the Speakers
Dr. Abhishek Tiwari
Consultant Interventional Cardiologist, Ahalia Hospital, Coimbatore
Financial Disclosure
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