Anticoagulation
Posted by dkwinter

See CHADS2 for guidance for patients with atrial fibrillation

Indications
     Acute coronary syndrome
          Low-molecular weight heparins
     Atrial fibrillation
          Aspirin
          Warfarin (with bridging heparin or possible LMWH)
     Coronary artery stent thrombosis prophylaxis
          Clopidogrel (Plavix)--only indicated for preventing in-stent thromboses following coronary artery stenting
     Thromboembolism/Stroke Prophylaxis
          Pradaxa (Dabigatran)
     Venous thromboembolism (DVT)
          Heparin
          Warfarin
          Low molecular weight heparins (E.g. enoxaparin)

Agents
     Aspirin--impairs platelets by blocking production of thromboxane A2
     Dabigatran--direct thrombin (factor II) inhibitor
     Rivaroxaban--direct factor Xa inhibitor
     Warfarin--impairs Vitamin-K-dependent carboxylation of factors II, VII, IX, X, C, S, and Z
     Heparin--binds and accelerates activity of antithrombin III inhibiting Xa (and IIa), requires a drip
     Lovenox--low molecular weight heparin specifically inhibits factor X

Lab tests
     INR (to monitor Warfarin therapy)
          Measures coagulation via extrinsic pathway and common pathway
          Factors involved are: II, VII, IX, X and fibrinogen.
          Recall that Vit-K dependent factors are II, VII, IX, X, C and S.
          Factor V, fibrinogen, Ca2+ and XIII are also involved in the common pathway downstream from VII.
          Target is generally 2.0-3.0.
     aPTT (to monitor Heparin therapy)
          Measures coagulation via the intrinsic pathway and common pathway
          Factors involved are: XII, XI, IX, VIII and X, V, II, fibrinogen, Ca2+, XIII.
          Target is generally 1.5 to 2.5 times the PTT baseline value.