Anticoagulant

An anticoagulant is a drug which treats and prevents thrombosis by targeting the coagulation factors in the coagulation cascade, thereby reducing the blood's tendency to form thrombi.

Anticoagulants are mostly used to prevent thrombosis in the venous circulation.

Anticoagulant drugs are widely used in medicine, both in internal medicine and surgery. Many patients are on anticoagulants. Anticoagulant drugs are never combined, unlike antiplatelet drugs.

Types

• Vitamin K antagonists (VKA)
• Unfractionated heparin (UFH)
• Low-molecular-weight heparin (LMWH)
• Direct oral anticoagulants (DOAC)

Indications

Anticoagulants are mostly used to prevent venous thrombosis, and in higher doses, treat them. These are the most important indications:

• Prevention of stroke in case of atrial fibrillation
• Mechanical prosthetic heart valve
• Acute myocardial infarction
• Nephrotic syndrome
• Prophylaxis for venous thromboembolism (DVT, PE)
  • Perioperative prophylaxis
  • Prophylaxis in case of immobilisation

Historically, vitamin K antagonists were generally used for longer-term anticoagulation, while unfractionated heparin was generally used for shorter-term anticoagulation. Nowadays, DOACs have mostly replaced the use of vitamin K antagonists, and LMWHs have mostly replaced the use of unfractionated heparin.

Most of the mortality and morbidity of atrial fibrillation comes from the fact that the inefficient atrial contractions predispose to the formation of thrombi, which can embolise and cause stroke. Many people with atrial fibrillation require indefinite anticoagulation to prevent this.

Adverse effect

The major adverse effect of anticoagulation is an increased risk of bleeding, especially intracranial bleeding in case of falls, and spontaneous gastrointestinal bleeding from ulcers or other lesions. These bleedings can be fatal.