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PR3154 > IC5- SPAF > Flashcards

IC5- SPAF Flashcards

1
Q

What is the pathophysiology of a cardio-embolic stroke?

A

Turbulent blood flow due to uncoordinated fibrillation of left atrium → circulatory stasis due to blood pool → clotting factors buildup in atrium → formation of blood clot → clot embolism → clot travels to the brain and blocks blood flow → stroke

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2
Q

Which are the 4 conditions where warfarin is used?

Can we use DOACs in these cases?

A
  1. Pts with mechanical heart valves
  2. Moderate-to-severe mitral stenosis
  3. Left ventricular thrombus
  4. APS-related VTEs (type of thrombophilia)

DOACs contraindicated in these cases.

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3
Q

What is the CHA2DS2VA(Sc) scoring to estimate stroke risk?

A
  1. Congestive HF (+1)
    - SSx of HF or objective evidence of reduced left ventricular ejection fraction, or hypertrophic cardiomyopathy
  2. HTN (+1)
    - Resting BP > 140/90 mmHg on ≥ 2 occasions; or
    - Current anti-HTN Tx
  3. Age ≥ 75 y/o (+2)
  4. Diabetes mellitus (+1)
    - Fasting glucose > 125 mg/dL (7 mmol/L); or
    - Tx with PO hypoglycemic agent and/or insulin
  5. Prior stroke/ TIA (+2)
  6. Vascular disease (+1)
    - Previous MI; or
    - Periphery artery disease; or
    - Aortic plaque
  7. Age 65-74 y/o (+1)
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4
Q

Are antiplatelets recommended for SPAF?

A

No

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5
Q

How do you determine when to start Tx based on the CHA2DS2VA score?

I.e. when the score is 0, 1 and ≥ 2?

A

Score = 0
- No anticoagulants
- Reassess stroke risk at least annually

Score = 1
- Consider anticoagulation
- Monitor pt with time to see if a 2nd risk factor appears (if it does then give anticoagulant)

Score ≥ 2
- Start anticoagulation therapy
- Consider DOAC over warfarin
- Conduct monitoring tests to ensure safe use of OAC therapy

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6
Q

What is the purpose of the HASBLED score?

A

To identify modifiable risk factors and mitigate them

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7
Q

For pts with a CHA2DS2VA score of 1, what type of pt groups have a higher stroke risk? (5)

A
  1. Age 65 - 74
  2. HF, age ≥ 35 y/o
  3. HTN, age > 50 y/o
  4. DM, age > 50 y/o
  5. Vascular disease, age ≥55 y/o
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8
Q

What is the “ABC pathway” for the management of AF?

A
  1. Avoid Stroke
    - Identify low-risk pts
    - Consider/ offer stroke prevention to those with ≥1 risk factors
    - Decide on OACs
  2. Better symptom control
    - Person-centred
    - Symptom-directed decisions on rate vs rhythm control
  3. Cardiovascular and other co-morbs or risk factor
    - Manage HTN, HF, DM, cardiac ischemia, sleep apnoea
    - Lifestyle changes: weight loss in obesity, regular exercise, ↓ alcohol/ stimulant use
    - Psychological morbidity
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9
Q

What are the HASBLED risk factors? And the points scoring?

Which are modifiable*?

A

*1. H (+1)
Uncontrolled HTN
- Systolic BP > 160 mmHg

  1. A
    - Abnormal renal function (+1): dialysis, renal transplant, SCr > 200 mmol/L
    - Abnormal liver function (+1): cirrhosis, bilirubin < 2x ULN, AST/ ALT/ ALP > 3x ULN
  2. S (+1)
    Stroke Hx
  3. B (+1)
    Bleeding Hx/ predisposition to bleeding

*5. L (+1)
Labile INRs (unstable or high INRs, or < 6 in 10 INRs were within therapeutic range)

  1. E (+1)
    Elderly (> 65 y/o) or extreme fragility

*7. D
- Drugs (+1): (e.g. antiplatelet medications, NSAIDs)
- Alcohol (+1): (> 14 units for men, > 7 units for women per week)

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10
Q

What is the “ABC” pathway for management of AF?

A
  1. Avoid stroke
    - Identify low-risk pts
    - Consider/ offer stroke prevention to those with ≥1 risk factors
    - Decide on OACs
  2. Better symptom control
    - Person-centred
    - Symptom-directed decisions on rate vs rhythm control
  3. Cardiovascular and other co-morbs or risk factors
    - Manage HTN, HF, DM, cardiac ischemia, sleep apnoea
    - Lifestyle changes: weight loss in obesity, regular exercise, ↓ alcohol/ stimulant use
    - Psychological morbidity
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11
Q

If the pt has high bleeding risk, what do we do if the cause of bleeding is known and treatable?

What do we do if the cause of bleeding is unknown or untreatable or irreversible?

A

If the cause of bleeding is known and treatable: restart DOAC

If the cause of bleeding is unknown or untreatable or irreversible: LAA occlusion (Watchman device)

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12
Q

Name 3 reasons DOACs are preferred over warfarin for SPAF?

A
  1. Warfarin associated with greater deterioration of renal function
  2. Pts on warfarin at risk of VKA-associated nephropathy and vascular calcification
  3. Avoid VKA if calciphylaxis or glomerular haemorrhage
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13
Q

What is the dosing for Dabigatran for SPAF?

What about for special considerations? And renal impairment?

A

Dabigatran: 150mg BD

Special considerations:
110mg BD IF
- Elderly ≥ 80 y/o
- Pgp inhibitor use
- High bleeding risk

Renal impairment:
- CrCl 30-50 ml/min: no need dosage adj unless DDI with potent Pgp inhibitors then 75mg BD
- CrCl < 30ml/min: contraindicated

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14
Q

What is the dosing for Rivaroxaban for SPAF? What about for renal impairment?

A

Rivaroxaban: 20mg OD

Renal impairment:
- CrCl 30-50 ml/min: 15mg OD
- CrCl 15-30ml/min: 15mg OD; use with caution
- CrCl < 15ml/min: contraindicated

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15
Q

What is the dosing for Apixaban for SPAF?

What about for special considerations? And renal impairment?

A

Apixaban: 5mg BD

Special considerations:
2.5mg BD if ANY 2
1. Age ≥ 80 years
2. Weight ≤ 60kg
3. SCr ≥ 1.5mg/dL (132.6mmol/L)

Renal impairment:
- CrCl 15-29 ml/min: 2.5mg BD

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16
Q

What is the dosing for Edoxaban for SPAF? At what CrCl must we avoid it?

What about for special considerations? And renal impairment?

A

Edoxaban: 60mg OD
AVOID if CrCl > 95 ml/min

Special considerations
30mg OD if any:
1. CrCl 30-50 ml/min (renal impairment)
2. Weight ≤ 60kg
3. Concomitant verapamil/ quinidine/ dronedarone

Renal impairment:
- CrCl < 15 ml/min: not recommended

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17
Q

What are the 4 enzymes which DOACs are metabolised by?

A

P-gp, BCRP, OATP and CYP3A4

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18
Q

Which DOACs are metabolised by P-gp? (BRAD)

A

(BRAD)
Betrixaban, Rivaroxaban, Apixaban, Dabigatran

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19
Q

Which DOACs are metabolised by BCRP? (BAR)

A

(BAR)
Betrixaban, Apixaban, Rivaroxaban

20
Q

Which DOACs are metabolised by OATP? (RED)

A

Rivaroxaban
Edoxaban
Dabigatran

21
Q

Which DOACs are metabolised by CYP3A4?

A

Apixaban (~25%), Rivaroxaban (~18%)

22
Q

Name some potent P-gp inhibitors

A

Verapamil, Quinidine, Dronedarone, Amiodarone

Azithromycin, Clarithromycin, Erythromycin

PO azoles: Itraconazole, ketoconazole, voriconazole, posaconazole

Ciclosporin

23
Q

Name some potent dual inhibitors of CYP3A4 and P-gp

A

PO azoles: Itraconazole, ketoconazole, voriconazole, posaconazole

Ritonavir

Clarithromycin

24
Q

Name some potent CYP3A4 inhibitors

A

Rifampicin

Carbamazepine, phenytoin, phenobarbital

St. John’s Wort

25
Q

Which 3 DOACs are better for the elderly?

A

Apixaban, Dabigatran and Edoxaban

26
Q

Which DOACs must be dose adjusted regarding low BW (< 60kg)?

Which DOACs are contraindicated in BW < 60kg?

A

Adjust dose for Apixaban, Edoxaban.

Avoid: Dabigatran, Rivaroxaban, Betrixaban

27
Q

Must DOACs must be dose adjusted regarding high BW (>120 kg)?

Which DOACs are contraindicated in BW > 120kg?

A

Use with caution Rivaroxaban, Apixaban

Avoid: Dabigatran, Edoxaban, Betrixaban

28
Q

Under what conditions should we monitor patients initiated on DOACs for SPAF

  1. Every 4 monthly
  2. Every CrCl/10 months
  3. Immediately
A
  1. Every 4 monthly
    - ≥ 75y (esp if on dabigatran), or frail
  2. Every CrCl/10 months
    - If CrCl < 60ml/min
  3. Immediately
    - In case of intercurrent conditions (eg. infection, NSAID use, dehydration etc.) (esp with the potential impact on renal/ hepatic function)
29
Q
A
30
Q

Considering warfarin therapy, which clotting factor plunges the fastest? What implication does this have on the INR?

Which clotting factor takes the longest to drop?

A

Factor VII plungest the fastest once warfarin is started. Hence the INR may increase rapidly initially

Factor II takes the longest to drop (longest t1/2)

31
Q

Explain the need for a bridging therapy for warfarin due to the initial hypercoagulable state

A

Warfarin also causes natural anticoagulant proteins C and S levels to be reduced quickly → hypercoagulable state initially.

Hence impt to cover pts with enoxaparin (LMWH) [clexane] for 2 consecutive days (bridging therapy) when giving them a high dose of warfarin.

If after 2 days, INR spikes, then hold off the LMWH and decrease warfarin dose

32
Q

What factors impact warfarin dose? (5)

A
  • INR stability → age ≥ 70 years, absence of chronic diseases
    I- NR instability → congestive HF, diabetes, target range of INR ≥ 3.0
  • Changes in vit K intake (food)
  • Gage et al predictors: body surface area (BSA), age, target INR, race, current thrombosis, current amiodarone use, smokers
  • PGx: VKOR, 2C9 polymorphisms, beneficial for those requiring ≤ 21mg/week or ≥ 49mg/week
33
Q

How does CYP2C9 and VKORC1 polymorphisms affect warfarin and what dose adjustments need to be made?

A
  • CYP2C9 polymorphism: decreases warfarin metabolism → ↑ sensitivity to warfarin → dose reduction
  • VKORC1 polymorphism: ↑ sensitivity to warfarin → dose reduction
34
Q

What must we take note (eg dosing) when we give DOAC with antimicrobial?

Why?

A

High microbiome load in gut = need larger warfarin dose

Disruption of gut bacteria (eg use of antimicrobials which kill off some microbiome) → less menadione (vit K) produced by gut → INR increase (fever can also cause INR increase)

35
Q

Name some inhibitors of 2C9 that we should avoid regarding warfarin therapy

A
  • Sulfamethoxazole/ Trimethoprim
  • Fluconazole
  • Voriconazole
36
Q

Name some inducers of 2C9 that we should avoid regarding warfarin therapy

A

Ritonavir, rifampicin

37
Q

For which drugs do we adjust warfarin dose preemptively? (4)

A
  • Bactrim (Sulfamethoxazole/ Trimethoprim)
  • Ciprofloxacin
  • Metronidazole
  • Rifampicin
38
Q

How often should INR be done?

A

Repeat INR in 3-5d after starting therapies, consider daily INR if admitted and unstable/ septic

39
Q

What are the 4 dietary and lifestyle factors and how will they affect INR? (↑/↓)?

A
  1. Alcohol binge
    Causes CYP450 inhibition
    ∴↑ INR
  2. Chronic alcoholism
    Causes CYP450 induction
    Increases warfarin metabolism
    ∴↓ INR
  3. Sudden increase in physical activity
    Increases warfarin metabolism
    ∴↓ INR
  4. Smoking
    Causes CYP450 induction
    Increases warfarin metabolism
    ∴↓ INR
40
Q

What are some food that interact with warfarin?

A

↑ anticoagulant effect:
- St John’s Wort
- Ginger
- Gingko

41
Q

What are the 4 drug-disease interactions with warfarin?

A
  1. Liver impairment
  2. Fluid retention
  3. Fever
  4. Thyroid disease
42
Q

How does liver impairment affect INR? (drug-disease interaction)

A

Decreased clotting factor synthesis and warfarin metabolism
∴↑ INR

43
Q

How does fluid retention affect INR? (drug-disease interaction)

A

Absorption from edematous gut vs liver congestion
∴↑ INR (liver)
∴↓ INR (gut)

44
Q

How does fever affect INR? (drug-disease interaction)

A

Increased metabolism and clotting disorders in sepsis
∴↑ INR

45
Q

How does thyroid disease affect INR? (drug-disease interaction)

A

Hyperthyroidism increases clotting factor turnover
∴↑ INR (hyper)
∴↓ INR (hypo)

46
Q

What are some impt warfarin counselling points?

A
  • Diet (avoid bingeing on Vit-K rich foods)
  • Alcohol
  • Illnesses (fever, n/v, diarrhoea)
  • Precautions (sports, cuts, accidents etc) → possible adverse events (🚩RED FLAG: upper GI bleeding which leads to black tarry stools)
  • Others (diarrhoea, n/v, general discomfort)
  • Pregnancy/ lactation → STOP warfarin and SWITCH to LMWH

PR3154 (11 decks)

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