Anticoagulation BCPS – Questions & Proper Solutions
What is the etiology of atrial fibrillation? ✔️Ans - Typically related to
structural heart disease (CAD, HF or HTN, etc)
Valvular heart disease
Noncardiogenic causes: Hyper- or hypothyroid disease, acute infection,
excessive alcohol intake, post-surgery, and PE
What is atrial fibrillation? ✔️Ans - A type of supraventricular
tachyarrhythmia
Incomplete conduction of supraventricular impulses
Conduction through the AV node is erratic and is revealed by the ECG as an
irregular rhythm
Why does atrial fibrillation increase the risk of thrombosis? ✔️Ans -
There is an incomplete conduction of supraventricular impulses creating a
lack of atrial contraction
Incomplete emptying of the cardiac chambers during systole increases the
rate of blood pooling in the atria (most notably in the left atrial appendage)
Blood stasis is associated with increased formation of mural thrombi
(which may cause arterial embolization or stroke if dislodged).
What is paroxysmal AF? ✔️Ans - AF that terminates spontaneously or
with intervention within 7 days
What is persistent AF? ✔️Ans - Continuous AF for more than 7 days
What is longstanding persistent AF? ✔️Ans - Continuous AF > 12
months in duration
What is permanent AF? ✔️Ans - Decision of the patient and clinician to
stop further attempts to restore and/or maintain NSR and remain in AF
What is non-valvular AF? ✔️Ans - AF in the absence of rheumatic mitral
stenosis, mechanical or bioprosthetic heart valve, or mitral valve repair.
What is the increase in risk of stroke in patients with NVAF? ✔️Ans - 5-
fold increased risk compared to patients without AF
,Responsible for 15 to 20% of strokes
Name the components in the CHADSVASc score ✔️Ans - Congestive
heart failure
HTN
Age > 75 (2 points)
Age 65-74
Diabetes
Stroke/TIA (2 points)
Vascular Disease
Female
Max of 9 points
Name the components in the HAS BLED score ✔️Ans - 1 point for each of
the following :
Hypertension
Abnormal renal or liver function (1 point each)
Stroke
Bleeding
Labile INRs
Elderly (age > 65)
Drugs or Etoh (1 point each)
HAS-BLED score of ≥ 3 = increased risk of major bleed (approx. 4% per
year)
What is warfarin's mechanism of action? ✔️Ans - Inhibits vitamin K
recycling by inhibiting vitamin K epoxide reductase > vitamin K reductase,
preventing y-carboxylation of clotting factors II, VII, IX, and X, leaving these
factors unable to bind to phospholipid membranes and unable to take part
in coagulation
What patients should receive a lower starting dose of warfarin? ✔️Ans -
Advanced age
Low body weight
Drug interactions
Malnourishment
, Heart failure
Hyperthyroid state
Low albumin or liver disease
Selected ethnic groups (e.g., Asians)
What are the half-lives of the clotting factors?
Factor II
Factor VI
Factor VII
Factor X ✔️Ans - Factor VII: 6 hr
Factor VI: 24 hr
Factor X: 36 hr
Factor II: 72 hr
Functional clotting factors must "run their course" and cannot be inhibited
by warfarin with higher doses, regardless of INR
Which is more dangerous: high or low INR? ✔️Ans - If the INR decreases
to 1.8 or less, the risk of ischemic stroke in NVAF increases by 60%,
whereas the risk of bleeding does not significantly increase until the INR is
greater than 4.0 (better to be a little high than a little low).
What drugs reduce warfarin absorption? ✔️Ans - Cholestyramine
Sucralfate
What drugs reduce INR by enzyme induction (increase risk of thrombosis)?
✔️Ans - Phenytoin
Phenobarbital
Carbamazepine
Rifampin
St. John's Wort
What drugs increase INR and warfarin effect? ✔️Ans - S-Warfarin (CYP
2C9/3A4): Metronidazole, bactrim, fluconazole, isoniazid, fluoxetine,
sertraline, amiodarone
R warfarin (CYP1A2/3A4/2C19): clarithromycin, erythromycin, azole
antifungals, fluoxetine, amiodarone, cyclosporine, sertraline, grapefruit
juice, ciprofloxacin, protease inhibitors, diltiazem, verapamil, isoniazid,
metronidazole)
What is the etiology of atrial fibrillation? ✔️Ans - Typically related to
structural heart disease (CAD, HF or HTN, etc)
Valvular heart disease
Noncardiogenic causes: Hyper- or hypothyroid disease, acute infection,
excessive alcohol intake, post-surgery, and PE
What is atrial fibrillation? ✔️Ans - A type of supraventricular
tachyarrhythmia
Incomplete conduction of supraventricular impulses
Conduction through the AV node is erratic and is revealed by the ECG as an
irregular rhythm
Why does atrial fibrillation increase the risk of thrombosis? ✔️Ans -
There is an incomplete conduction of supraventricular impulses creating a
lack of atrial contraction
Incomplete emptying of the cardiac chambers during systole increases the
rate of blood pooling in the atria (most notably in the left atrial appendage)
Blood stasis is associated with increased formation of mural thrombi
(which may cause arterial embolization or stroke if dislodged).
What is paroxysmal AF? ✔️Ans - AF that terminates spontaneously or
with intervention within 7 days
What is persistent AF? ✔️Ans - Continuous AF for more than 7 days
What is longstanding persistent AF? ✔️Ans - Continuous AF > 12
months in duration
What is permanent AF? ✔️Ans - Decision of the patient and clinician to
stop further attempts to restore and/or maintain NSR and remain in AF
What is non-valvular AF? ✔️Ans - AF in the absence of rheumatic mitral
stenosis, mechanical or bioprosthetic heart valve, or mitral valve repair.
What is the increase in risk of stroke in patients with NVAF? ✔️Ans - 5-
fold increased risk compared to patients without AF
,Responsible for 15 to 20% of strokes
Name the components in the CHADSVASc score ✔️Ans - Congestive
heart failure
HTN
Age > 75 (2 points)
Age 65-74
Diabetes
Stroke/TIA (2 points)
Vascular Disease
Female
Max of 9 points
Name the components in the HAS BLED score ✔️Ans - 1 point for each of
the following :
Hypertension
Abnormal renal or liver function (1 point each)
Stroke
Bleeding
Labile INRs
Elderly (age > 65)
Drugs or Etoh (1 point each)
HAS-BLED score of ≥ 3 = increased risk of major bleed (approx. 4% per
year)
What is warfarin's mechanism of action? ✔️Ans - Inhibits vitamin K
recycling by inhibiting vitamin K epoxide reductase > vitamin K reductase,
preventing y-carboxylation of clotting factors II, VII, IX, and X, leaving these
factors unable to bind to phospholipid membranes and unable to take part
in coagulation
What patients should receive a lower starting dose of warfarin? ✔️Ans -
Advanced age
Low body weight
Drug interactions
Malnourishment
, Heart failure
Hyperthyroid state
Low albumin or liver disease
Selected ethnic groups (e.g., Asians)
What are the half-lives of the clotting factors?
Factor II
Factor VI
Factor VII
Factor X ✔️Ans - Factor VII: 6 hr
Factor VI: 24 hr
Factor X: 36 hr
Factor II: 72 hr
Functional clotting factors must "run their course" and cannot be inhibited
by warfarin with higher doses, regardless of INR
Which is more dangerous: high or low INR? ✔️Ans - If the INR decreases
to 1.8 or less, the risk of ischemic stroke in NVAF increases by 60%,
whereas the risk of bleeding does not significantly increase until the INR is
greater than 4.0 (better to be a little high than a little low).
What drugs reduce warfarin absorption? ✔️Ans - Cholestyramine
Sucralfate
What drugs reduce INR by enzyme induction (increase risk of thrombosis)?
✔️Ans - Phenytoin
Phenobarbital
Carbamazepine
Rifampin
St. John's Wort
What drugs increase INR and warfarin effect? ✔️Ans - S-Warfarin (CYP
2C9/3A4): Metronidazole, bactrim, fluconazole, isoniazid, fluoxetine,
sertraline, amiodarone
R warfarin (CYP1A2/3A4/2C19): clarithromycin, erythromycin, azole
antifungals, fluoxetine, amiodarone, cyclosporine, sertraline, grapefruit
juice, ciprofloxacin, protease inhibitors, diltiazem, verapamil, isoniazid,
metronidazole)
