TBL 1: Stroke Prevention in Atrial Fibrillation

Question 1

what is the most common pathologic arrhythmia?

Answer 1

atrial fibrillation

it increases in prevalence with increasing age; 10-15% of pts over 80 yrs

Question 2

what is the major concern with atrial fibrillation?

Answer 2

arterial embolism of a left atrial thrombus resulting in ischemic stroke, peripheral limb ischemia, or other end organ damage

AF is associated with a 3- to 6-fold increased risk of stroke or non-central nervous system (CNS) systemic embolism

the risk of arterial thromboembolism can be significantly reduced with anticoagulant therapy (warfarin, apixaban, dabigatran, edoxaban or rivaroxaban) and, to a lesser extent, with antiplatelet therapy

Question 3

how is the thrombotic risk of a patient with AF evaluated?

Answer 3

CHADS2 score:
Ⓒongestive heart failure

ⒽTN history

Ⓐge > 75 yrs

Ⓓiabetes

Ⓢtroke history

in general, pts with CHADS2 score >1, the risk of arterial thromboembolism without anticoagulation outweighs the risk of bleeding from anticoagulants

Question 4

what should you take into consideration when considering someone’s bleeding risk?

Answer 4

patients at increased risk for bleeding, typically, are also those who will benefit the most from anticoagulation to prevent stroke, and attempts should be made to modify bleeding risk factors

this includes trying to limit things like NSAID use, alcohol use, and frequent falls

this is because the risk-benefit ratio almost always favours anticoagulation unless the risks for bleeding are very high

Question 5

what is the anticoagulant of choice for the prevention of stroke in patients with AF?

Answer 5

it used to be warfarin

but now, newer direct oral anticoagulants (DOACs) like apixaban, dabigatran, edoxaban, and rivaroxaban are used increasingly for this indication, and are suggested in preference to warfarin

Question 6

what are the benefits of direct oral anticoagulants over warfarin? disadvantages?

Answer 6

ADVANTAGES
1. fixed, once- or twice-daily oral dosing

2. noneed for routine coagulation monitoring
3. few known or defined drug interactions
4. no known food interactions
5. lower risks of intracranial bleeding

DISADVANTAGES
1. lack of readily available reversal agents in case of major bleeding

2. varying degrees of renal elimination requiring dose adjustment in pts with renal insufficiency

Question 7

what anticoagulation therapy should be given to pts <65 years with AF at low risk of stroke?

Answer 7

if they have no other risk factors then no antithrombotic therapy is needed

Question 8

what anticoagulation therapy should be given to pts <65 years with AF who have coronary artery or vascular disease?

Answer 8

81 mg aspirin daily

Question 9

what anticoagulation therapy should be given for patients with AF and an intermediate/high stroke risk (CHAD2 >1)?

Answer 9

DOAC or warfarin

DOAC is the preferred choice

Question 10

how do you decide what anticoagulation therapy to give for AF patients?

Answer 10

are they over 65 years old?

if yes, give DOAC

if not then evaluate other risk factors like HTN, previous stroke, DM etc and if they have any then give DOACs

if they don’t have any risk factors and are under 65 yrs old, check to see if they have CAD/arterial vascular disease –> if they do, give 81 mg aspirin

if they don’t have CAD/arterial disease and no risk factors then no anti thrombotic therapy is needed

Question 11

when is warfarin recommended over DOACs?

Answer 11

in patients with AF and who also have valvular heart disease because they are at significantly increased risk for ischemic stroke

treatment with a DOAC is NOT recommended in these patients