Anticoagulation

Question 1

anticoagulant to use with history of HIT

Answer 1

argatroban

Question 2

MOAs

Answer 2

UFH, LMWH, fondaparinux - bind to antithrombin
LMWH - inhibit factor Xa
warfarin - Vit. K agonist

Question 3

direct thrombin inhibitors

Answer 3

do not cross react with HIT antibodies
argatroban - DOC if hx of HIT
bivalirudin (Angiomax)
dabigatran (Pradaxa) - oral - do not use with prosthetic valve - antidote: idarucizumab (Praxbind)

Question 4

Factor Xa inhibitors

Answer 4

apixaban (Eliquis)
betrixaban (Bevyxxa)
edoxaban (Savaysa)
rivaroxaban (Xarelto)
fondaparinux - injectable
do not require lab monitoring, no antidote
do not use if prosthetic heart valve

Question 5

UFH

Answer 5

binds to antithrombin, inactivates thrombin IIa and Xa, prevents conversion to fibrinogen
used to keep IV lines open
antidote: protamine
s/e: thromboxytopenia, HIT, hyperkalemia, osteoporosis

Question 6

LMWH

Answer 6

bind to antithrombin, more affinity for Xa than IIa
enoxaparin (Lovenox)
dalteparin
do not use with hx of HIT
s/e: elevated LFTs, thrombocytopenia

Question 7

HIT

Answer 7

immune mediated IgG rxn
Abs bind to heparin, lead to further platelet activation
can cause prothrombotic state = amputations
starts 5-14 days after herparin dose, w/in hours is heparin given in last 3 months
s/sx: unexplained drop in PLTs >50% of baseline

Question 8

HIT treatment

Answer 8

stop all heparin and LMWH
stop warfarin, give Vit. K
if hx of HIT, use argatroban for anticoagulation

Question 9

Warfarin

Answer 9

Coumadin, Jantoven
racemic mixture - S enantiomer more potent
c/i in pregnancy unless mech heart valve
goal 2-3, 2.5-3.5 if mech mitral valve
start dose: 10mg/day x2d, then adjust
in DVT/PE pts, continue enoxaparin/UFH x5d when starting warfarin

Question 10

Warfarin interactions and genetics

Answer 10

2C9*2 or *3 or VCORC1 = increased bleed risk
2C9 inducers lower INR: rifampin, St. Jphn’s wort
2C9 inhibitors raise INR: amiodarone, fluconazole, Flagyl, Bactrim
decrease warfarin 30-50% if starting amiodarone
5 Gs increase bleeding: garlic, ginger, ginkgo, ginseng, glucosamine

Question 11

Warfarin reversal

Answer 11

Vit. K, phytonadione (Mephyton), prothrombin concentrate (Kcentra)
supratherapeutic INR <4.5, no bleeding: reduce dose
INR 4.5-10, no bleed: hold 1-2 doses
INR >10, no bleed: hold, give Vit. K
major bleed: give IV Vit. K

Question 12

perioperative warfarin (bridging therapy)

Answer 12

stop warfarin 5 days before surgery
if mech valve, A-fib, VTE, embolism risk = bridging therapy w/ UFH or LMWH
d/c LMWH 24 hrs before surgery
d/c UFH 4-6 hrs before surgery
resume warfarin 12-24 hrs after surgery

Question 13

VTE prophylaxis

Answer 13

if can’t use anticoag: use pneumatic compression devices
VTE risk factors: surgery, trauma, immobility, cancer, VTE hx, pregnancy, estrogen meds, ESAs
for long-distance travelers: move frequently, compression, aspirin +anticoag should NOT be used

Question 14

VTE treatment

Answer 14

pts w/o cancer: dabigatran and Xa inhibitors (rivaroxaban, apixaban, edoxaban) preferred over warfarin for first 3 months
cancer pts: LMWH preferred

Question 15

Atrial Fibrillation

Answer 15

Rapid Ventricular Response
pts w/ mechanical valves get warfarin (2.5-3.5)
CHADS2-VASC scoring used
score 0 = no anticoag
score 1 = aspirin 75-325 daily or possible anticoag
score 2+ = anticoag (warfarin, dabigatran, rivaroxaban, apixaban) or aspirin + clopidogrel if unable to use anticoag

Question 16

CHADS2-VASC

Answer 16

CHF (1), HTN (1), age 75+ (2), Diabetes (1), Stroke/TIA hx (2), Vascular disease/MI/PAD (1), Age 65-74 (1), Sex Category Female (1)

Question 17

Anticoag Counseling

Answer 17

seek treatment if bleeding, red/black stools, bloody coffee ground vomit, unusual bruising
enoxaparin - do not expel air bubble
dabigatran - take w/ full glass of water
rivaroxaban - take w/ food, take missed doses ASAP