Anticoagulation refers to the use of medication to reduce the blood’s ability to clot, lowering the risk of dangerous clot formation within the heart, blood vessels, or veins. Anticoagulant drugs are commonly prescribed to cardiac patients, including some cardiac arrest survivors, for conditions where clot risk is elevated.
Why anticoagulation is used
The most common reasons for prescribing anticoagulation in the context of cardiac and cardiac arrest care include:
- Atrial fibrillation (AF): AF causes turbulent blood flow in the left atrium, promoting clot formation. Clots can travel to the brain and cause a stroke. Anticoagulation significantly reduces this risk.
- Pulmonary embolism: clots in the leg veins (deep vein thrombosis) that travel to the lungs. Anticoagulation treats and prevents recurrence.
- Mechanical heart valves: patients with mechanical valve replacements require lifelong warfarin to prevent valve-related clotting.
- Left ventricular thrombus: a clot that forms in the left ventricle after a large heart attack. Anticoagulation is given until the thrombus resolves.
Types of anticoagulant
- Warfarin: an older anticoagulant requiring regular INR blood tests to monitor and adjust the dose. Still used for mechanical valves and some other indications.
- Direct oral anticoagulants (DOACs): including apixaban, rivaroxaban, edoxaban, and dabigatran. These are now preferred over warfarin for most AF patients and venous thromboembolism, as they do not require routine blood monitoring and have a more predictable effect.
- Low molecular weight heparins (LMWH): injected anticoagulants used in hospital settings and for certain indications.
Risks
All anticoagulants increase the risk of bleeding. The treating clinician balances the risk of clotting against the risk of bleeding when deciding whether to prescribe anticoagulation.
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