SPAF Flashcards
pathophysiology of SPAF
- AFib -> uncoordinated contraction in left atrium -> turbulent flow -> accumulation of clotting factors inside left atrial appendage -> form clot
- clot breaks off -> embolise to left ventricle -> travel to aorta -> travel to cerebral circulation -> clot stuck in vessel -> cut off circulation -> stroke
types of diagnostic tests used for SPAF
1) CHADVAS: estimate stroke risk
2) HASBLED: estimate bleeding risk
CHADVAS for SPAF
1) scoring
- 1 point: CHF, HTN, DM, vascular disease (prior MI, peripheral artery disease, aortic plaque), age 65 - 74
- 2 point: age ≥ 75, prior stroke/transient ischaemic attack
2) what scores mean
- ≥ 2: start OAC
- 1: can consider OAC + monitor
- 0: no need
HASBLED for SPAF
1) Scoring (1 point each)
- HTN > 160 mmHg
- abnormal renal/liver function (1 point each)
- previous stroke
- bleeding history
- labile INR (unstable, high, < 6 in 10 INR in therapeutic range)
- age > 65 yo
- drugs (NSAID, antiplatelet)
- alcohol ≥ 8 units per wk
2) what scores mean
- ≥ 3 = high bleeding risk
decisions to make when deciding therapy for SPAF
1) when to give DOAC
- non valvular AFib (not mitral stenosis)
- < 6 in 10 INR in therapeutic range
- X tolerate warfarin
- difficulty assessing/dislike frequent INR monitoring
2) when to give warfarin
- valvular AFib (mitral stenosis)
- ≥ 6 in 10 INR in therapeutic range
- X tolerate DOAC
- moderate - severe liver/renal impairment
- if pt using rifampicin
apixaban for SPAF
1) dosage
- normal: 5mg BD
- 2.5mg BD if
** any 2 of: ≥ 80 yo, weight ≤ 60, SCr ≥ 1.5 mg/dL
** CrCl 15 - 29 mL/min
2) CI
- severe liver/renal impairment (CrCl < 30 or HD)
- pregnancy, lactation
- APS, heart valve replacement, azoles
rivaroxaban for SPAF
1) advantages over apixaban
- OD dosing
- wider indication (ACS)
2) dosing
- normal: 20mg OD
- CrCl 30 - 50: 15mg OD
3) contraindication
- severe renal/liver impairment (CrCl < 30 or HD)
- pregnancy, lactation
- APS, heart valve replacement, azoles
dabigatran for SPAF
1) dosing
- normal: 150mg BD
- ≥ 80 yo, use pgp-i or high bleeding risk: 110mg OD
2) contraindication
- severe renal/liver impairment (CrCl < 30)
- pregnancy, lactation
- APS, heart valve replacement, azoles
edoxaban for SPAF
1) dosing
- normal: 60mg BD
- CrCl 30 - 60, weight ≤ 60, concomitant AF drug: 30mg BD
2) CI
- not used when good renal clearance
- severe renal/hepatic impairment
- pregnancy, lactation
- APS, heart valve replacement, azoles
warfarin for SPAF
1) indications for SPAF
- APS, liver disease, on rifampicin
2) dosing
- individualised dosing according to INR (normal 2.5, heart valve replacement 3, reduce INR by 25% if on bactrim/ciprofloxacin)
monitoring and follow up for SPAF
1) repeat CHADVAS and HASBLED
- 1st follow up in 1month, afterwards annually
2) monitor blood sampling
- 1st follow up in 1 month, afterwards annually
- if ≥ 80 yo then once every 4 months
- if CrCl < 60 then CrCl divided by 10 (e.g. if CrCl 45 then every 4 months)
3) monitor for
- adherence, thromboembolism, bleeding, SE, co-meds, blood sampling, minimise risk factors for bleeding
special populations for SPAF
1) old people
- dementia, compliance
- frailty and falls
- use apixaban
2) lower body weight
- lower body weight need dose adjustment for Apix and Edoxaban
switching between DOAC and warfarin and vice versa for SPAF
1) Warfarin to DOAC
- don’t need bridge
- if TTR < 60% then
** INR ≤ 2.5: stop warfarin, start DOAC
** if INR 2.5 - 3: stop warfarin, start DOAC immediately, check INR in 3 days
** if INR > 3: stop warfarin, recheck INR in 3 days
2) DOAC to warfarin
- need bridge: continue DOAC with warfarin for 3 - 5 days before stopping DOAC
- why need bridge? onset of warfarin takes awhile
