IC5 - Stroke Prevention (AP)

Question 1

When is DOACs not recommended for stroke prevention in AF?

Answer 1

1. Mechanical heart valve
2. Mod to severe mitral stenosis

Question 2

What is the preferred treatment in stroke prevention in AF?

Answer 2

DOACs

Question 3

How is stroke risk estimated?

Answer 3

Via CHA2DS2-VASc

Question 4

When should OAC be started in stroke patients with AF?

Answer 4

score ≥ 2

Question 5

Mr Tan’s stroke risk is accounted to be 0. What are the measures to take?

Answer 5

1. No need OACs
2. Reassess stroke risk annually or when clinical circumstance changes

Question 6

Patients with CHA2DS2-VASc score of 1 should be considered for anticoagulants by looking at their ______.

Answer 6

risk factors

Question 7

_______ are not recommended for preventing AF-related stroke.

Answer 7

Antiplatelet

Question 7

What are the factors in the HAS-BLED score.

Answer 7

H - Uncontrolled HTN (Systolic > 160)
A - Abnormal renal, live function
S - Stroke History
B - Bleeding History or risk
L - Labile INRs (Unstable/ high INR/ <6 in 10are within range)
E - Elderly (>65) or extreme frailty
D - Drugs (Antiplatelet/NSAID), Alcohol (>14units men or 7units women per week)

Question 8

HAS-BLED score is _____ correlated to bleeding.

Answer 8

poorly

Question 9

______ and _______ are dosed based on specific criteria.

Answer 9

Apixaban, edoxaban

Question 10

What are the three risk factors to consider when dosing Apixaban?

Answer 10

1. Elderly (Age≥80yo), Underweight (≤60kg)
2. Renal function (SCr≥1.5mg/dL or 132.6mmol/L)
3. DDI

Question 11

Dose adjustment for Rivaroxaban is required when CrCl is __________.

Answer 11

less than 50ml/min

Question 12

Dose adjustment for Apixaban, Edoxaban, Dabigatran is required if __________.

Answer 12

less than 30ml/min

Question 13

In which situation should vitamin K antagonists should be avoided for stroke prevention?

Answer 13

Vascular calcification
Calciphylaxis
Glomerular hemorrhage

Question 14

When dosing according to renal functions, _______ equation is used.

Answer 14

Crockroft Gault

Question 15

What are the considerations when starting DOACs in stroke prevention elderly patients?

Answer 15

1. Dementia, compliance
2. Frailty (associated with rapid deterioration of renal functions) and Falls

Question 16

What is the choice of DOACs in low body weight (<60kg)?

Answer 16

Apixaban and Edoxaban

Question 17

All DOACs have DDI with _______.

Answer 17

P-GP substrates

Question 18

Which 2 DOACs are CY3A4 substrate?

Answer 18

Apixaban and Rivaroxaban

Question 19

For patients with ________, loading doses of warfarin are usually given.

Answer 19

existing clots

Question 20

What are the factors affecting the maintenance dose?

Answer 20

Polymorphisms in VKOR, 2C9 (Beneficial for those requiring ≤ 21mg/week or ≥49mg/week.)

Question 21

What happens to INR of wafarin when patient is given an antimicrobial that will interact with wafarin?

Answer 21

INR increases

Question 22

What are two antimicrobials that will require adjustment in warfarin dose preemptively?

Answer 22

Bactrim (Cotrimoxazole) and ciprofloxacin

Question 23

When should INR be repeated for patients who are concurrently on warfarin and Cotrimoxazole or Ciprofloxacin?

Answer 23

Repeat INR in 3-5days after starting therapy
Daily if admitted and unstable/septic

Question 24

List 4 diet and lifestyle interactions with warfarin.

Answer 24

1. Alcohol Binge (inhibit CYP450, increase INR)
2. Chronic Alcholism (induce CYP450, increase warfarin metabolism, decrease INR)
3. Sudden increase in physical activity (increase warfarin metabolism, decrease INR)
4. Smoking (CYP450 enzyme induction, increase metabolism, decrease INR)

Question 25

List 4 Drug Disease interaction in Warfarin.

Answer 25

Liver Disease - Increase INR
Fluid retention - Increase INR (liver), decrease (gut)
Fever - Increase INR
Thyroid Disease - Increase (hyper), decrease (hypo)

Question 26

List the components in the CHA2-DS2-VAS.

Answer 26

Congestive heart failure
Hypertension
Age ≥ 75 (2 points)
Diabetes
Previous stroke, transient ischemic attack or thromboembolism (2 points)
Vascular disease
Age 65 to 74
Sex female

Question 27

What is the target INR for patients with mechanical heart valves?

Answer 27

2.5 to 3.5

Question 28

What are two ways to reverse warfarin effect?

Answer 28

Vitamin K and fresh frozen plasma

Question 29

Mr Tan has an INR of >10 after being on warfarin therapy for SPAF. What should be given to him to reduce effects of warfarin.

Answer 29

PO vitamin K (2mg to 5 mg)

Question 30

When can we consider withholding warfarin or provide vitamin K at 1-2mg to patients?

Answer 30

1. INR<10
2. Minor bleed

Question 31

What should be done when patient has major bleed while on warfarin?

Answer 31

Withhold or if INR>1.5, provide IV vitamin K 5-10mg

Question 32

What is a medication contraindicated with DOACs?

Answer 32

Rifampicin (potent P-gp and CYP3A4 induction)

Question 33

List some common DDI associated with DOACs.

Answer 33

1. Antiseizure - carbamazepine, phenytoin, phenobarbital, valproic acid
2. Herbal - St John’s Wart
3. PO azoles
4. Clarithromycin
5. Ritonavir

Question 34

What are some methods to reverse DOACs effect?

Answer 34

1. Withhold if renal function normal, non-life threatening bleed
2. If urgent: Praxibind, Andexanet Alfa
3. Dabigatran: Possible dialysis but may not be effective
4. xaban: Prothrombin complex concentrate

Question 35

How can warfarin be switched to DOACs?

Answer 35

1. wait 3 days and measure INR
2. Ensure INR below 2 before starting DOACs

Question 36

How can DOACs be given to a patient who needs to switch to warfarin?

Answer 36

No need to withhold. Ensure INR of warfarin is within goal and stop DOACs in 3 to 5 days