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3154 Haematology > IC5 SPAF > Flashcards

IC5 SPAF Flashcards

1
Q

Explain how AFib can result in stroke

A

AFib in the left atrial appendage can lead to clot formation due to turbulent blood flow

Clot in the heart can embolize into left ventricle => aorta => cerebral circulation

Embolus in cerebral artery blocks blood flow to the brain, leading to brain tissue death and stroke

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2
Q

Why are DOACs recommended over VKAs in SPAF?

A
  • Better outcomes in terms of prevention of stroke or systemic embolism, intracranial hemorrhage, and major bleeding outcomes (as effective in reducing AF-related strokes and systemic embolism, a/w fewer ICH. but incr GI bleed)
  • noninferior efficacy, less major bleeding
  • DOAC benefit preserved across deteriorating renal function (unlike Warfarin - a/w greater deterioration of renal function due to VKA-associated nephropathy, vascular calcification, glomerular hemorrhage)
  • Less DDIs
  • No need for monitoring (unlike warfarin - narrow TI, require frequent titration)

Other:

  • pt w less than 6 out of 10 INR readings within therapeutic range (labile INR) while on Warfarin
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3
Q

When is warfarin still required?

A
  • Valvular AF (Mechanical/Prosthetic heart valves, mod-severe mitral stenosis)
  • Left ventricular thrombus
  • APS
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4
Q

In what situation might Warfarin be favoured over DOAC?

A
  • Pt who can maintain 6 out of 10 INR readings within therapeutic range (labile INR) while on Warfarin
  • Pt unable to tolerate side effects of DOAC
  • Pt with mod-severe liver or renal impairment
  • Pt with clinically significant DDI with DOAC
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5
Q

Ischemic stroke risk scoring: CHA2DS2-VASc score

A
  • Congestive HF (1)
  • HTN (1)
  • Age 75 or older (2)
  • DM (1)
  • Previous stroke, TIA, or thromboembolism (2)
  • Vascular disease e.g., MI, PAD, aortic plaque (1)
  • Age 65-74 (1)
  • Sex - Female (1)
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6
Q

Based on CHA2DS2-VASc score, when to initiate OAC for SPAF?

A

Score of >=2 in men, and >= 3 in women

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7
Q

HASBLED score to estimate bleeding risk

A
  • HTN >160mmHg
  • Abnormal renal function / liver function
  • Stroke (history)
  • Bleeding (history or predisposition)
  • Labile INR
  • Elderly >65yo
  • Drugs (e.g., antiplatelets, NSAIDs) / Alcohol (>=8 units per week)
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8
Q

How is HASBLED score used to determine use of anticoagulants in SPAF?

A
  • Identify non-modifiable factors, and address modifiable risk factors (e.g., control BP, stop concomittant antiplatelet)
  • Score is poorly correlated with actual bleeding, hence high bleeding risk score is NOT a reason to withhold OAC
  • Pt identified to have high bleeding risk should be scheduled for early and more frequent reviews and follow-up
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9
Q

ABC pathway of SPAF

A

Avoid stroke

  • Identify low-risk patients
  • Offer SPAF to those with >=1 risk factors (start if >=2)
  • Decide on OAC

Better symptom control

  • Person-centred and symptom-directed decisions on rate vs rhythm control (rate control more impt)

Cardiovascular and other comorbidities or risk factors

  • Manage HTN, HF, DM, cardiac ischemia, sleep apnea
  • Lifestyle changes - weight, exercise, alcohol
  • Psychological morbidity
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10
Q

What might be used for SPAF if pt has major bleeding, and cannot use OAC

A

Left atrial appendage (LAA) occlusion

  • Watchman device implanted to catch clot and prevent clot from entering circulation
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11
Q

[SPAF dosing + renal adjustments]
- Apixaban

A

5mg BD

2.5mg BD for any 2 of the following:

  • age >=80yo
  • weight =<60kg
  • SCr >= 1.5mg/dL or 132.6mmol/L

RENAL ADJ:
CrCl 15-29ml/min: 2.5mg BD
CrCl <15ml/min: NO INFO
HD: 5mg BD approved by FDA

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12
Q

[SPAF dosing + renal adjustments]
- Rivaroxaban

A

20mg per day

RENAL ADJ:
CrCl 30-50ml/min: 15mg per day
CrCl 15-30ml/min: 15mg OD use with caution
CrCl <15ml/min: Contraindicated

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13
Q

[SPAF dosing + renal adjustments]
- Edoxaban

A

60mg per day

30mg per day if any of the following:

  • CrCl 30-50ml/min
  • weight =<60kg
  • concomitant PGP inhibitors: verapamil, quinidine, dronedarone

RENAL ADJ:
CrCl 30-50ml/min: 30mg per day
CrCl 15-30ml/min: 30mg per day
CrCl <15ml/min: not recommended

CrCl >95ml/min: avoid due to incr risk of stroke

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14
Q

[SPAF dosing + renal adjustments]
- Dabigatran (most renally cleared)

A

150mg BD

110mg BD if >=80yo, or use of PgP inhibitors, or high risk of bleeding

RENAL ADJ:
CrCl >50ml/min: 150mg BD, 110mg BD if >80yo or high bleeding risk
CrCl 30-50ml/min: same as above, but 75mg BD if DDI with potent PGP inhibitors
CrCl <30ml/min: contraindicated
CrCl 15-30ml/min: 75mg BD (FDA)

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15
Q

Evidence of OAC use for SPAF in elderly

A

DOACs have better outcomes in terms of prevention of stroke or systemic embolism, intracranial hemorrhage, and major bleeding outcomes as compared to Warfarin

*Unadjusted doses seem to be a/w better outcomes

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16
Q

Which two DOACs are preferred in elderly?

A

Apixaban
Edoxaban

17
Q

Evidence of OAC use for SPAF in low body weight

A

BW range: 60-120kg

Lower BW require dose adjustment: Apixaban (2.5mg BD), Edoxaban (30mg OD)
(recall =<60kg)

  • AVOID Dabigatran, Rivaroxaban

Higher BW (obesity >40kg/m2, weight >120kg) suggest to use with caution: Rivaroxaban, Apixaban

  • AVOID Dabigatran, Edoxaban
18
Q

VKA in SPAF

  • What are the targets?
A

INR 2-3 (only if mechanical aortic heart valve: 2.5-3.5)

TTR: 70%

19
Q

[SPAF structure follow up]

Baseline monitoring parameters before OAC initiation

A
  • Blood test (include Hb, renal/liver function, coagulation panel)
20
Q

[SPAF structure follow up]

Interval for follow-up (blood sampling) after initiation of OAC

Blood sampling: Hb/FBC, renal, liver function

A

First FU after 1 month, subsequent:

  • Default: YEARLY
  • Every 4 months for >=75yo (esp if on Dabigatran/Edoxaban or frail - renal function decreases with age)
  • Every CrCl/10 if CrCl =<60ml/min
  • Immediately in the case of intercurrent conditions (esp conditions with potential impact on renal or hepatic functions, e.g., NSAID use, infection, dehydration)
21
Q

[SPAF structure follow up]

Structured follow-up after initiation of OAC

A
  • Adherence
  • Thromboembolic S&S (DVT, PE, Stroke)
  • Bleeding events (reason for bleed - treat or prevent)
  • Side effects (continue or change?)
  • Comedications (e.g., NSAIDs)
  • Blood sampling (Hb/FBC, renal, liver)
  • Assess and minimize modifiable risk factors for bleeding (uncontrolled HTN >160mmHg, concurrent meds, alcohol intake)
  • Assess optimal DOAC choice and dosin
22
Q

Switching from DOAC to Warfarin

  • INR <2
  • INR >=2
A
  • Start VKA while on DOAC (half dose for edoxaban)
  • If INR <2, continue DOAC and repeat INR after 1-3days (measure INR before DOAC intake)
  • If INR >=2, stop DOAC, repeat INR 1 day after stopping
23
Q

Switching Warfarin to DOAC

  • INR <2
  • INR 2-2.5
  • INR 2.5-3
  • INR >=3
A
  • Stop VKA and measure daily INR (the lower the baseline INR< the shorter the time needed to withhold VKA)
  • When INR <2, start DOAC immediately
  • If INR 2-2.5, start today/tomorrow
  • If INR 2.5-3, recheck INR in 1-3 days
  • If INR >=3, postpone DOAC, hold warfarin 3 days, TCU day 4 for INR
24
Q

[Bleeding while using NOAC]

  • what should be determined first?
A
  • NOAC dose, time of last intake
  • Co-medications
  • Blood sampling - determine CrCl, hepatic function, WBC
  • Rapid coagulation assessment
  • Plasma drug levels (if available)
25
Q

[Bleeding while using NOAC]

Management of MILD bleeding in pt taking DOAC

A
  • Delay or discontinue next dose => DOAC have relatively short half-life ~12h, easy to reverse effects when discontinued/withhold
  • Reconsider any concomitant medication
  • Reconsider choice of NOAC and dosing
26
Q

[Bleeding while using NOAC]

Management of NON-LIFE THREATENING MAJOR bleeding in pt taking DOAC

A
  • Delay or discontinue next dose
  • Add on supportive measures: mechanical compression, surgical/endoscopic hemostasis, fluid replacement, RBC/platelet substitution, adjuvant transexamic acid
  • Treat any factors/comorbidities contributing to the bleed
  • Consider reversal agent - idarucizumab for Dabigatran (or consider dialysis to clear Dabigatran)
27
Q

[Bleeding while using NOAC]

Management of LIFE-THREATENING/BLEEDING INTO CRITICAL STATE in pt taking DOAC

E.g., critical state: into spinal cord, heart, abdominal space etc.

A
  • Delay or discontinue next dose
  • Add on supportive measures
  • For Dabigatran: IV Idarucizumab
  • For FXa inhibitor DOACs: Andexanet alpha (not available in SG)
  • For DOACs: PCC/aPCC (activated prothrombin complex concentrates)
28
Q

DOAC - unplanned invasive procedure

A

Determine time to hold off DOAC before invasive procedure

Patient factors:

  • e.g., age, stroke risk, bleeding risk, recent CVD events, medications, renal function
  • *As renal function worsens, time to hold off increases

Surgical factors:

  • e.g., bleeding risk of procedure, consequence of bleeding
29
Q

Duration of Warfarin in different indications

  • DVT, PE, thrombus
  • SPAF
  • Valvular heart disease
  • Mechanical heart valve
  • Bioprosthetic heart valve
A

DVT: 3m

PE: 3m

SPAF: lifelong

Valvular heart disease (mitral stenosis): lifelong

Mechanical heart valve: lifelong

Bioprosthetic heart valve: 3-6m

Left ventricular thrombus: 3 months, repeat TTE to document resolution before stopping

30
Q

Why do pt with mechanical heart valves require lifelong warfarin therapy?

A
  • Thrombogenecity of intravascular prosthetic material
  • Abnormal flow conditions imposed by mechanical valves, low flow and high shear stress can cause platelet activation, leading to valve thrombosis and embolic events
  • Also, INR target is higher 2.5-3.5 due to the thrombogenicity risk
31
Q

[REVERSAL]

Warfarin reversal

  • INR <4.5
  • INR 4.5-10
  • INR >10
A

INR <4.5
- repeat INR, redose as needed

INR 4.5-10
- withhold warfarin
- repeat INR, redose as needed
- DO NOT administer Vit K (if do: PO Vit K 1-2mg)

INR >10
- withhold warfarin
- PO Warfarin 2-5mg
- Repeat INR and restart warfarin as necessary

32
Q

[REVERSAL]

What are some independent predictors of slow normalization of INR? (INR remain elevated)

A
  • Advanced age >=70yo
  • Decompensated HF
  • Acute malignancy
  • Low weekly warfarin dose
33
Q

[REVERSAL]

Warfarin reversal

  • Major bleeding
  • Minor bleeding
A

Major bleeding
- withhold warfarin
- IV Vit K 5-10mg if INR >1.5
- Transfusion of platelets (FFP)
- Supplement with PCC for life-threatening bleed
- Repeat PT/INR/APTT 1h later

Minor bleeding
- withhold warfarin
- assess bleeding risk vs thromboembolic risk
- PO Vit K 1-2mg or IV 1mg

34
Q

[REVERSAL]

Why is too much Vit K not desirable?

A

DO NOT DOSE 10mg

  • too much Vit K –> resistance/delayed anticoagulation for up to 3 weeks
  • those with high thrombogenic risk will not be able to prevent thrombus expansion
35
Q

[REVERSAL]

Compare efficacy of oral vs IV Vit K

A

Similar effect at 24-48h

36
Q

[REVERSAL]

Dabigatran

A
  • withhold 1-2 days if renal function normal, non life-threatening bleed
  • dialysis (not likely effective)
  • idarucizumab (most effective if urgent reversal needed)
37
Q

[REVERSAL]

Apixaban/Rivaroxaban

A
  • withhold 1-2 days if renal function normal, non life-threatening bleed
  • Prothrombin complex concentrates PCC (not likely effective)
  • Andexanet alpha (most effective if urgent reversal needed, NA in SG)
38
Q

[REVERSAL]

Warfarin

A
  • withhold
  • Vit K
  • Fresh frozen plasma - transfuse platelets (require large volume)
  • PCC (most effective if urgent reversal needed)

3154 Haematology (14 decks)

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