SPAF Flashcards
AF sequelae
cardio-embolic stroke
- Uncoordinated contraction in LA
- Clot formation in appendages (LA)
a. Circulatory stasis - Emboli to brain
Cerebral infarction
AF ECG readings
Irregularly irregular rhythm · No P waves
valvular AF
moderate or severe mitral stenosis (LA –> LV)
presence of mechanical prosthetic heart valve
= WARFARIN
non-valvular AF
includes AF with other valvular heart lesions
= DOAC
SPAF
Anticoagulants - VKA
- Reduce stroke risk by 64%, 26% death in AF pt
- Mitral stenosis, mechanical heart valves
SPAF anticoagulants – DOAC preferred?
- Reduce ischemic stroke by 19%, risk of hemorrhage by 50%
- Recommended to all other AF pts
○ CHA2DS2-VASc score =/>2 (offered) ○ CHA2DS2-VASc score <2 (considered)
CHA2DS2 VA
CHF
HTN
Age =/> 75yo (2)
DM
stroke, TIA, thromboembolism (2)
vascular disease
age 65-74
CHADSVASC score 0 (M,F) need to tx?
- No anticoag
- No antiplt (aspirin, * clopidogrel not recom for SPAF)
CHADSVASC score 1 (M,F) meaning
Consider anticoag based on risk factors
CHADSVASC score =/>2
Offer, recommended warfarin/ NOAC
Discuss bleeding risk factors, tx options
favour warfarin (in general)
- maintain INR within therapeutic range TTR 70%
- SE of DOAC
- mod-severe liver or renal impairment
- sig DDI with DOAC
- valvular AF, APS
- GI alterations
favour DOAC
- pt unable to monitor INR (venous access/ lab access)
- reluctant to monitor VKA, narrow TI)
- DDI
- ease of dosing
- safer (less major bleeds)
bleeding risk HASBLED
max 9
HTN > 160mmHg
Abnormal renal function SCr > 200umol/L OR Ab liver function AST, ALT >3X [1,1]
stroke (hx)
bleeding (hx / predispose)
labile INR (<6/10 in range)
elderly (>65yo)
Drug (antiplt, NSAID, alc >8unit/wk) [1,1pt]
HASBLED scores
0 = low risk
1-2 = mod risk
=/> 3 = high risk
what to do if there is high risk for bleeding
- assess risk of stroke vs bleeding
- cause of bleeding
- identify & tx comor (HTN)
continue NOAC, dont stop unless CI
consel on need
1) stroke risk
2) SE of OAC – mitigate bleeding risk
3) compare DOAC or VKA
ABC pathway
A: avoid stroke, OAC
B: better sx control (rate BB, CCB> rhythm Na, K)
C: CVS and other comor risk factors
OAC dose for Afib
dabigatran
150mg BD
110mg BD (if =/>80yo/ use PGPi/ high risk of bleed)
no crcl dose adj unless CI <30ml/min
OAC dose for Afib
rivaroxaban
20mg OD
crcl 30-50ml/min : 15mg OD
CI: <15 ml/min
OAC dose for Afib
apixaban
5mg BD
2.5mg BD (any 2: age=/>80yo, weight =/<60kg, scr =/> 1.5mg/dL or 132mmol/L)
crcl 15-29: 2.5mg BD
OAC dose for Afib
edoxaban
60mg OD
30mg OD (if ANY 1: crcl 30-50ml/min, weight =/<60kg, concom verapamil, quinidine, dronedrone)
CI: crcl<15
interval for FU depends on
1mnth: initiate
4mnth: =/>75yo, frail, dabi
crcl/10 mnth: crcl =/< 60ml/min
immediate: hep, renal function (NSAID, infection, dehydration)
at each FU check for:
1) adherence (cognitive, minor bleeds)
2) thromboembolism
3) bleeding (cause??)
4) SE
5) co-medications (aspirin, NSAID)
- blood sampling (hb, LFT, CrCL)
- minimise bleeding risk factors (HTN, medication, INR)
- optimal choice of DOAC?dose?
how much is metabolised by lvier
DRAW
VKA: INR (risk nephropathy, vas calcification)
15-29: consider benefit vs harm
D: 80% kidney 0% substrate, inhibitor, inducer
R: 66% liver metabolised
A: 75% liver
W: 99% liver
E: 50% liver metabolised
why cockcroft gault
CKD-EPI, mdrd: determine staging of CKD
parameters for crcl by CG
gender
actual BW (if morbid obese = IBW)
age
SCr
elderly considerations
1) dementia and compliance
2) frailty and falls (but benefit > risk)
- edoxaban, apixaban
low BW choice
60-120kg
lower BW = dose adj (apix, edoxaban)
high BW chocie
rivaroxaban (OD and wider indication range)
apixaban (BD, easy to use in special pop)
DOAC DDI
CYP450 enzymes (apix 25%, 50% riva, edo)
PGP substrate (apix, dabig, riva, edox)
BCRP (apix, riva)
OATP (riva)
potent PGPi
(think of edoxaban)
verapamil, quinidine, dronedarone, amiodarone
macrolides
PO azoles: itra, keto, voric, posa
ciclosporin
potent CYP3A4 inducer
rifampicin, CBMP, PT, PB
st john wort
potent dual CYP3A4, PGP inhibitor
PO azole
ritonavir
clarithromycin
potent dual CY3A4, PGP inducer
valproic acid
liver impairment and DOAC
child pugh A
child pugh B (caution, except edoxa/ riva: not recomm)
child pugh C: DO NOT USE
vka: INR 2-3
warfarin interindiv response
genetic (VKORC1, CYP2C9)
environmental factors
new factors
pgX FOR
1) existing clots (left V thrombus)
2) outpt commencement
3) complex DDI
4) questionable adherence
clotting factor t1/2 ranking
II > Protein S > X > IX> protein C > VII
II: 42-72hrs
protein S: 60hr
load warfarin because?
- LMWH (sc)
hypercoagulable state 4-5d, due to low prot S,C
long time to deplete vit K lvls
long t1/2, many clotting factors involved
esp if existing clot
what affects INR
eg: indian higher mean daily dose (VKORC1)
PGx (esp if =/< 21mg/wk or =/>49mg/wk)
chronic diseases, CHF, DM
diet, compliance
PK DDI of warfarin
Absorption from gut
Protein bind: NSAID use
CYP450, CYP2C9 inhibition/ induction
transporter enzymes
CYP2C9 inhibitors
preemptive dose adj
(amiodarone, fluconazole, metronidazole)
CYP2C9 inducer
rifampicin (preemp adjust)
CBMZP
PB
st john wort
antimicrobials effect on INR
disrupt gut bacteria, less menadione (vit K)
incr INR
DDI with Abx
preemptive (SMX-TMP, cipro, metro)
macrolides, amox/clav, doxy
monitor INR
3-5 days after start therapy
1-3d if unstable
daily (admitted, unstable/ septic)
alcohol and INR
○ Binge: CYP450 enzyme inhibition
INR blip incr
○ Chronic: CYP450 enzyme induced
INR: decr
Incr physical activity
Incr warfarin meta
INR decr
Smoking
CYP450 induction
Incr warfarin meta
INR decr
Liver impairment
Decr clotting factor synthesis
Decr warfarin meta
INR incr
Fluid retention
Absorp from oedematous gut vs liver congestion
INR incr (liver, warfarin stay in body longer, more effect)
INR decr (gut, dilute, less warfarin effect)
fever
Incr metabolism, clotting disorders, incr turnover of clotting factors
Esp in sepsis
INR incr
Thyroid disease
Hyperthyroidism incr clotting factor turnover
INR incr
high vit K diet
leafy greens (kale, spinach etc)
beef, prok
canola oil
green tea, chrysanthemum, herbal teal, soybean
DOAC coagulation assays deranged
PT
aPTT
ACT
DOAC bleeding management
mild bleed: continue (reconsider concmitant meds)
mod: supp tx (fluid replacement, tx cause of bleed GIT)
severe: prothrombin complex conc, reversal agents
reversal agents for DRAW
D: Idarucizumab 5g IV
* Renally CL, can dialysis
R, A: Andexanet alfa/ PCC
W: PCC (prothrombin complex)
* Fresh frozen plasma
* Vit K (IV 5-10mg)
* Overcorrection (high dose of vit K) assoc with delayed re-anticoagulation (up to 3wks)
unplanned invasive procedure
acute (in mins)
- reversal of NOAC
urgent (in hrs)
- defer 12-24hr? hold off only if high bleeding risk
expedited (days)
- defer surgery if possible
repeate coag panel after surgery
switching from NOAC –> VKA
Use NOAC like LMWH bridge (3-5d, along with VKA)
INR > 2: stop NOAC, repeat INR 1day after
INR <2: continue NOAC, repeat INR 1-3day
switching from VKA –> NOAC
stop VKA wait til __ to start NOAC
-Based on t1/2 of clotting factors (by warfarin inhibition)
- Low INR: withhold less days (2-3 days)
□ INR =/<2: start NOAC (has shorter t1/2, no need load) * Unlike VTE - darbi, edoxa need LMWH □ If 2-2.5: KIV start current or next day □ If INR >3: hold warfarin, repeat INR 1-3day, decide based on INR