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.
