Atrial fibrillation Flashcards
Define paroxysmal AF
Episodes lasting > 30 seconds but < 7 days (often < 48h) that are self-terminating and recurrent
Define persistent AF
Episodes lasting > 7 days or < 7 days but require pharmacological or electrical cardioversion
Define permanent AF
AF that:
- fails to terminate using cardioversion
- terminates but relapses within 24h
- longstanding AF > 1y in which cardioversion has not been indicated or attempted (accepted permanent AF)
Causes of AF
Most common:
1) HTN
2) CAD
3) MI
Other cardiac causes:
1) Congestive HF
2) Rheumatic valvular disease
3) Atrial or ventricular dilation or hypertrophy
4) WPW
5) Sick sinus syndrome
6) Congenital heart disease
7) Inflammatory or infiltrative disease (pericarditis, amyloidosis, myocarditis)
Non-cardiac causes:
1) Acute infection
2) Autonomic neuronal dysfunction
3) HypoK and HypoNa
4) Cancer: lung, breast, malignant melanoma mets
5) PE
6) Thyrotoxicosis
7) DM
8) Excessive caffeine, alcohol, smoking, obesity
9) Thyroxine, bronchodilators
Prevalence of AF
Most common cardiac arrhythmia - 2.5%
M > F
Lifetime risk for women aged 40y - 26% and aged 80y - 22.7%
5% > 70y 10% > 80y
AF complications
1) Increased risk of CVA (2.3x) and stroke severity is greater when associated with AF than with other causes
2) Peripheral thromboembolism
3) Heart failure (5x): ineffective ventricular filling
4) Tachycardia induced cardiomyopathy and critical c cardiac ischaemia is persistently raised ventricular rate
5) 96% increased risk of major cardiovascular event
6) 88% increased risk of sudden cardiac death
7) Reduced QoL and impaired cognitive function
Risks from paroxysmal AF thought to be similar to persistent/permanent AF
Management of AF if onset within last 48h
1) Assess haemodynamic stability, unstable if :
- HR >150
- Systolic BP < 90
- severe dizziness/syncrope
- chest pain/increasing SOB
2) Haemodynamically unstable - urgent admission for electrical cardioversion
3) Haemodynamically stable: manage in primary care or admit for immediate cardioversion (electrical or amiodarone/felcainide)
4) Herpanise if AF definitely < 48h
5) If < 48h, after electrical cardioversion further anticoaglation is unecessary
Management of AF started > 48h ago
1) Haemodynamically unstable - admit
2) Investigations to r/o causes:
- ECG
- FBC, U&E, BP, TFT, Mg, HbA1c
- NT ProBNP if HF
- Echo - murmur
3) Refer for consideration of pharmacological or electrical cardioversion:
- AF with reversible cause (chest infection)
- HF caused or worsened by AF
- first episode
4) Refer to cardiology:
- WPW
- Valvular disease associated with AF
- Suspected HF +/- previous MI
5) CHA2DS2VASC and ORBIT
6) DOAC : risk of stroke 5x higher in AF, anticoagulant reduces risk by 2/3
- offer if CHA1CS2VASc > 2 (women) or > 1 (men) if benefit > risk
- do not offer if < 65y and no RF other than sex (1 for women or 0 for men)
7) If DOAC not suitable - offer Vit K antagonist and if neither suitable offer aspirin + clopidogrel
8) Offer rate-control treatment:
- BB (not sotalol) or rate-limiting CCB (diltiazem/verapamil)
- digoxin is alternative in non-paroxysmal AF if sedentary and can’t have BB or CCB or prefer digoxin
9) F/U 1 week after starting rate-control treatment:
- symptoms, HR, BP, drug tolerance
- switch to alternative rate-control drug if not tolerated
- if HR/symptoms/BP not controlled - increase dose of current drug
- if taking max dose offer combination treatment, 2 of BB, diltiazem (off-label), digoxin
- Specialist advice before BB + diltiazem - bradycardia, AV block, asystole, sudden death
10) If symptoms or HR not controlled on combination treatment - refer for cardioversion (4ww)
When would ablation be considered and what are the risks?
How long are DOACs needed before and after ablation?
Consider if not responded to anti-arrythmics or preference
Risks - cardiac tamponade/CVA/pulmonary vein stenosis
DOAC needed 4 weeks prior to ablation
CVA risk not reduced by ablation therefore anticoagulate based on CHADSVASC score
Left atrial ablation
- 50% can stop taking some/all heart rhythm medications after procedure
- paroxysmal AF - 80% feel better after and 33% need repeat ablation within 3y
- persistent AF - 50% feel better after , 80 % after 2 ablations, and 10% need repeat ablation within 3y
AV node ablation + pacemaker
- 80% can stop taking some/all heart rhythm medications after procedure
- 80% feel better
- 3% need repeat procedure within 3y
- battery replacement within 10y
Driving after ablation procedure
G1: no driving for 2 days, 1 week after pacemaker.
G2: no driving for 6 weeks
Flying with AF
No restrictions if stable
Driving with AF
G1: if it has caused/likely to cause incapacity to stop driving. Restart when cause identified and controlled for 4 weeks
G2: if it has caused/likely to cause incapacity to stop driving. Restart when controlled for 3 months + LVEF >= 0.4
Check with insurer that they are still covered
CHA2DS2VASc Score Tool
Assess stroke risk in patients with AF:
Congestive heart failure/HFrEF or decompensated HF requiring hospitalisation = 1
HTN > 140/90 x2 or on current treatment = 1
Age >= 75y = 2
DM (fasting BM > 7 or treatment) = 1
Stroke/TIA = 2
Vascular disease (MI, PAD or aortic plaque) = 1
Age 65 - 74 = 1
Sex female = 1
Rate of thromboemolic events/year:
0 - 0 %
1 - 1.3%
2 - 2.2%
3 - 3.2%
4 - 4%
5 - 6.7%
6 - 9.8%
7 - 9.6%
8 - 6.7%
9 - 15.2%
Offer anticoagulant if >=2 or to men if >=1
ORBIT scoring tool
To assess bleeding risk when deciding on anticoagulation
2 points for -
- males with Hb < 130 or Hct < 40%
- females with Hb < 120 or Hct < 36%
- history of bleeding (GI, intracranial, hemorrhagic stroke)
1 point for:
- > 74y
- eGFR < 60.
- on antiplatlet
Results -
0 - 2 - low risk
3 - medium risk (4.7 bleeds/100 pt years)
4 - 7 - high
Target for rate control in AF
60-80 at rest
90-115 during moderate exercise
Which combination of rate-limiting drugs should you seek advice for before prescribing?
BB + diltiazem
Bradycardia, AV block, asystole, sudden death
Follow-up after starting warfarin
Warfarin:
- INR daily or alternate days until 2-3 on 2 consecutive occasions
- then twice weekly for 1-2 weeks.
- then weekly until 2x INR 2-3
- then depends on stability - can be up to 12 weeks
Time in therapeutic range (TTR):
- calculate over period of 6 months, excluding first 6 weeks
Poor control:
- TTR < 65%
- 2x INR > 5 or 1x INR > 8 in past 6m
- 2x INR < 1.5 in past 6m
Annual AF review
1) Symptoms during rest & exercise
2) HR
3) If on rate-control with persistent symptoms:
- increase dose to maximum tolerated
- combination treatment - 2 of BB, diltiazem (off-label), digoxin (advice if BB + diltiazem)
- refer if not controlled on combination treatment to be seen in 4 weeks.
4) Review CHA2DS2VASC and ORBIT
5) Review DOAC/warfarin
BB in AF:
Licensed in AF
AF alone/ +MI (no HF)/ + HF/ +DM
CI and cautions
SE
Interactions
Licensed in AF - atenolol, acebutolol, metoprolol, nadolol, oxprenolol, propranolol
AF alone: atenolol 50-100mg as once daily and less expensive
Previous MI without HF: metoprolol (standard release), propranolol (standard release) or atenolol
AF + HF: bisoprolol, carvediolol, nebivolol
AF + DM:
- cardio-selective BB.- atenolol, bisoprolol, metoprolol, nebivolol.
- Avoid if experiencing frequent hypo’s.
Check pulse and BP 1 week after each dose titration
CI:
1) Asthma, COPD (if no alternative can use cardio-selective BB bisoptolol/atenolol) + concomitant bronchodilator therapy
2) Cardiogenic shock or phaechromocytoma (without alpha blocker)
3) 2nd/3rd degree HB without pacemaker
4) HR < 60bpm at start of treatment
5) Systolic BP < 100mmHg
6) Severe PAD: pain at rest and sometimes intermittent claudication
7) Uncontrolled HF - seek advice if current/recent exacerbation
Caution:
1) DM
2) 1st HB
3) Myasthenia gravis
4) Portal HTN - risk of deteriorating liver function
5) Psoriasis - can cause exacerbation
SE:
1) impotence, loss of libido - 5/1000
2) Pyschoses
3) sleep/nightmares
4) Low PLT
5) Visual disturbance
6) Vertigo
Interactions:
1) Increased hypotensive effect:
alpha-blockers, ACEi/ARB, baclofen, co-dopa, diuretics, nitrates
- tricyclics, mirtazapine, trazodone
- steroids/HRT
3) Anti-DM - mask hypo symptoms
4) CCB - never prescribe BB + verapamil!
5) Class I anti-arrythmics (qunidine/flecanide) - bradycardia and myocardial depression
6) Class II anti-arrythmics (amiodarone) - caution - risk of bradycardia, AV block, myocardial depression
7) Clonidine - risk of withdrawal HTN - withdraw BB several days before clonidine
8) Dobutamine - severe hypotension and bradycardia if non-cardioselective
9) NSAIDS - antagonise hypotensive effect
Diltiazem (off-label) and verapamil:
Dose
CI & cautions
SE
Interactions
Diltiazem:
- 60-120mg TDS (180-480mg MR)
- Renal or hepatic impairment/elderly - 60mg BD
Verapamil:
- 40-120mg TDS
CI D + V:
1) LVF with pulmonary congestion
2) HR < 50bpm (V) / < 40bpm (diltiazem)
3) 2nd/3rd HB, unless ventricular pacemaker
4) Systolic BP < 90
5) Severe aortic stenosis
6) With ivabradine
7) Pregnant or of child-bearing potential
CI V:
1) WPW
2) Acute MI complicated by bradycardia, marked hypotension or LVF
Caution:
1) Risk of bowel obstruction - reduced intestinal motility
2) 1st HB
3) D - DM - may increase BM
SE:
1) Av block, asystole
2) V - constipation
3) D - bronchospasm
Interactions:
1) Increased hypotensive effect with other antihypertensives /clonidine /co-copa /tricyclics /mirtazapine
2) Amiodarone - increased bradycardia, AV block
3) Enhances effects of cabamazapine - alter dose
4) Increases colchicine toxicity -suspend/reduce dose - avoid combination of colchicine + rate-limiting CCB in hepatic/renal impairment.
5) BB + V = contradicted. D = caution
6) Clarithromycin/erythromycin - reduced metabolism of CCB –> increased SE
7) Dabigatran - increased by V
8) Statins - increased risk of myopathy with simvastatin, V increased by atorvastatin and increased risk of myopathy (reduce atorvastatin dose).
Digoxin:
CI & cautions
Dosing
CI & cautions
SE, toxicity and monitoring
Interactions
Dosing:
- loading dose of 250 - 750mcg OD for 7 days. Clinic response usually within 1 week.
- maintenance dose 125 - 250mcg OD
- review at 1 week
CI:
1) WPW / AV block / VT or VF
2) HOCM - though can be used with caution if concomitant AF
Caution:
1) Recent MI
2) Thyroid disease
3) Severe respiratory disease
4 HypoK, HypoMg, HyperCa, Hypoxia (hisk of toxicity)
5) Renal impairment / elderly
SE:
1) Cardiac: SA or AV block, PVCs, PR prolongation, ST depression
- ECG changes (do not indicate toxicity) - scooped ST depression in II, III, avF, V5/6 (reverse tick)
2) Non-cardiac:
- nausea (OD), diarrhoea
- blurred/yellow vision
- weakness, dizziness, confusion, malaise, headache
- Thrombocytopenia and agranulocytosis
- gynaecomastia
Toxicity:
- confusion, nausea, vomiting, anorexia, disturbance of colour vision
- can occur even if digoxin level in normal range (0.7 - 2ng/mL)
Monitoring:
- not for routine monitoring of digoxin levels, but check U&E at least every 12m
- check if symptoms of toxicity / suspect poor adherence
- Take blood sample >6h (ideally 8-12h) after previous dose
Interpreting results:
< 1.5ng/mL + normal K - unlikely toxicity
> 3.0 - toxicity likely
1.5 - 3 - possible
Interactions:
1) Antidepressants: avoid tricyclics, venlafaxine, trazadone
2) BB:
- increased risk AV block, monitor pulse
- increased risk of toxicity with carvedilol
3) Diuretics, acetazolamide, amphotericin: increased cardiac toxicity if hypoK occurs
4) PPI - omeprazole, pantoprazole increases digoxin level
Drugs which increase digoxin levels:
1) Amiodarone
2) Antimicrobials: itraconazole, macrolide ABx, tetracycline, trimethoprim
3) CCB: diltiazem, verapamil, nifedipine
4) Chloroquine/hydroxychloroquine
5) Spironolactone
Choosing between warfarin and DOAC
Equal for preventing stroke in AF
DOACs - reduced risk of hemorrhagic stroke and intracerebral haemorrhage
DOACs have short half life therefore adherence is vital - effect fades after 12-24h and with warfarin lasts for 48-72h after missing a dose
No need for coagulation monitoring with DOAC
No specific antidotes for DOAC but are steps that and be taken if major bleed to reverse their effect
Amiodarone:
Always initiated in secondary care
Baseline tests: TFT, LFT, U&E, CXR, ECG
Monitoring:
1) TFT every 6m and for 12m after stopping
2) LFT, U&E every 6m
3) ECG every 12m
4) Annual eye test
SE:
1) Nausea, vomiting, taste disturbance
2) Pneumonitis, fibrosis - SOB, dry cough, fatigue, weight loss, fever
3) Hyper or hypothyroidism in 4%
4) Hepato-biliary disorders: cirrhosis, hepatitis, jaundice
5) Cardiac toxicity: bradycardia, block
6) Visual disorders: corneal micro deposits (dazzled by headlights at night), optic neuritis
7) Neurological: tremor, ataxia, peripheral neuropathy
8) Photosensitivity reactions: can persist for months after stopping, grey-blue skin discolouration - protect skin from light during treatment and after
Interactions:
1) BB, CCB
2) Colestyramine- reduces amiodarone levels by 50%
3) Donepezol, rivastigmine - increased bradycardia
4) Drugs that prolong QT - citalopram, escitalopram, amitriptyline, lithium, haloperidol
5) CYP3A4 inhibitors: increase amiodarone - erythromycin, azaleas, protease inhibitors
6) CYP3A4 inducers: reduce Amiodarone - carbamazapine, sildenafil, phenytoin
7) Digoxin: increases digoxin
8) simvastatin - do not exceed 20mg
9) Stimulant laxative, Senna: hypoK
10) Warfarin - increased anticoagulant effect
If no need for anticoagulation based on CHADSVASC score and has AF, what should be checked?
Echo to exclude valve disease as AF + valve disease is an absolute indication for anticoagulation
Catheter ablation for AF and anticoagulation
Anticoagulation for 4 weeks before and during the procedure
Controls rhythm but does not reduce stroke risk, therefore still needs anticoagulation based on CHADSVASC:
- 0 - 2 months anticoagulation recommended
- >=1 - longterm anticoagulation recommended
50% recurrence of AF within 3m that resolves spontaneously
55% at 3y will remain in sinus rhythm
80% of those having multiple procedures will be in sinus rhythm
Amiodarone or flecainide for pharmacological cardioversion in AF
Structural heart disease: amiodarone
No structural heart disease: amiodarone or flecainide
Cardioversion in AF - anticoagulation
< 48h of AF prior to cardioversion - no anticoagulation needed afterwards
> 48h AF - give anticoagulation for at least 3 weeks before cardioversion or do TOE to exclude L atrial appendage (LAA) thrombus - if excluded can be heparinised and electrically cardioverted immediately
- if high risk of electrical cardioversion failure (previous failure/recurrence) then give at least 4 weeks amiodarone or sotalol prior to electical cardioversion
- following electrical cardioversion patients should be anticoagulated for at least 4 weeks, then reassess based on risk of recurrence
What is the main reason to check U&E prior to amiodarone?
To detect hypoK - increases risk of arrythmia
Rhythm vs rate control in AF
Symptomatic, < 65y + 1st presentation or CHF - rhythm control
> 65y, history of IHD - rate control
Warfarin - MOA
Inhibits epoxide reductase preventing the reduction of vitamin K to its active form
This in turn acts as a cofactor in the carboxylation of clotting factor II, VII, IX and X (mnemonic = 1972) and protein C.
Warfarin - SE
Haemorrhage, skin necrosis, purple toes
Warfarin indications and target INR
- Mechanical heart valves (MV higher INR than AV)
- VTE - 2.5, recurrent = 3.5
- AF - 2.5
What potentiates warfarin?
- Liver disease
- P450 enzyme inhibitors, e.g.: amiodarone, ciprofloxacin
cranberry juice - Drugs which displace warfarin from plasma albumin, e.g. 4. NSAIDs
- Inhibit platelet function: NSAIDs
Monitoring INR when starting warfarn
- INR daily/alternate days until 2-3 on 2 consecutive readings
- Then twice weekly until 2x INR 2-3
- Then can check up to every 12 weeks depending on stability
What is TTR?
Time in therapeutic range over 6m (not including first 6w)
Poor control: TTR < 65%/ 2x INR > 5/ 1x INR > 8 in 6m or 2x INR < 1.5
