c_af_mxdetails
Table of Contents
Detailed Mx of AF in the ED
see also:
- calculators:
-
- aiming for a resting heart rate of <110 beats per minute is preferable to more strict rate control
- patients considered poor candidates for warfarin treatment, a combination of clopidogrel and aspirin appeared to be more efficacious than aspirin alone but also conferred a higher bleeding risk
Goals
- 1. If haemodynamically unstable (eg. BP< 80) with rapid ventricular rate then
- ⇒ ensure senior support & consider immediate synchronised DC cardioversion (see below)
- BUT NO defib if chronic AF as risk of DC reversion likely to outweigh benefit
- 2. Is it AF?
- If so, is it chronic or paroxysmal.
- 3. Search for underlying cause if new AF:
- % of emergency admissions with AF:
- 47% ischaemic heart disease
- NB. in new AF in those under 60yrs with no prior IHD or prior ischaemic chest pain, IHD is unlikely to be the cause.
- 18% hypertension (in 50% cases - Framington Study)
- 15% rheumatic heart disease
- 4% thyroid disease
- 17% other :-
- cardiac:
- sick sinus syndrome
-
- a very fast rate > 200 +/- variable QRS morphology suggests an accessory pathway
- cardiomyopathy
- ASD
- atrial myxoma
- short QTc - rare, but this may be life threatening!
- non cardiac:
- acute infections, esp. pneumonia
- alcohol excess, withdrawal or sensitivity
- lung carcinoma
- other intrathoracic pathology (e.g. pleural effusion)
- post-op (esp. after thoracotomy)
- 4. Are there any precipitating factors present?
- AMI
- acute respiratory distress
- acute alcohol ingestion
- thyrotoxicosis
- sepsis
- 5. Is cardioversion appropriate?
- It is generally considered that unless patient is severely compromised due to the AF, the risks of DC reversion probably outweigh the benefits as:
- most paroxysmal AF will revert of its own accord within 48hrs
- risk of stroke from dislodging an atrial thrombosis - particular if chronic AF or new AF > 48hrs
- DC reversion may in itself create a pro-thrombotic state of the atria
- to be prudent, one should liaise with the cardiology unit first before undertaking semi-elective reversion as they should have a TOE performed first, and many advise therapeutic anticoagulation for at least 3 weeks prior to cardioversion and then for 4 weeks after successful cardioversion1)
- sync. DC cardioversion in the ED is probably only warranted if either:
- haemodynamic compromise due to rapid AF
- wide QRS complexes
- after discussion with cardiology in patients who either have:
- TOE evidence of no thrombi
- perhaps very short duration AF with no risk factors, particularly if WPW as these pts have higher risk from rate controlling agents.
- Atrial flutter or WPW as rate control not useful
- Consider initial 200J DC with propofol and fentanyl
- 6. Determine long term or ongoing Rx:
- If ongoing AF or high risk of intermittent AF then consider ongoing Rx:
- rate control aiming for ventricular rate < 110 beats/min:
- this will relieve symptoms of congestive heart failure, hypotension or angina that can be directly attributed to a rapid heart rate.
- 36% will present in CCF, 10% as AMI, 8% as angina.
- anti-thrombotic therapy:
- this is the ONLY long term Rx shown to decrease mortality in pts with AF.
- start anticoagulation if:
- benefits outweigh risks of anticoagulation such as (see antithrombotic Rx for prevention of stroke):
- age > 75yrs
- on aspirin, clopdogrel or NSAIDs
- polypharmacy and compliance issues
- PH peptic ulcer of haemorrhagic stroke
- a new study seems to show dabigatran is safer and much more effective at preventing stroke in pts with AF than is warfarin.
- in addition, if paroxysmal AF lasting > 48hrs:
- consider referring to cardiology for echo & elective cardioversion:
Initial Emergency Department Management of the Patient with AF:
ECG:
- in particular, look for:
- flutter (ie. flutter waves - seen best in inferior leads; usually 2:1 block with ventricular rate of 150)
- pre-excitation syndromes (e.g. WPW) (esp. if young patient or rate > 200 or variable QRS morphology).
- DDx:
- SVT - has regular RR interval but rapid AF the variability in RR may be subtle.
- VT - AF with BBB may be difficult to distinguish from VT - check for regular RR interval of VT
- atrial extrasystoles - P-waves should be visible.
- multifocal atrial tachycardia - varying P waves preceding most QRS complexes
- PAT with variable block
- atrial flutter with variable AV conduction - consider a dose of adenosine to reveal the flutter waves.
IV Bung & Bloods
- FBE ± clotting if on or possibly may start warfarin.
- Urea and Electrolytes
- cardiac enzymes if ? acute coronary syndrome
- TFTs if have not been done, although low pick up rate if 1st episode lone AF
urgent Mx if haemodynamically unstable (BP < 80mmHg and HR > 120bpm)
- senior consultation & consider immediate DC reversion:
- sedation/short GA with propofol and fentanyl
- 150-200J synch DC reversion (see below)
- monitor ECG, vitals for at least 1 hour after
- if not anticoagulated and AF duration > 48hrs, start IV heparin or clexane
Chest X-ray to look for
- pulmonary or intrathoracic pathology
- cardiac failure/heart size
- evidence of ASD
Decide on treatment plan depending on patient’s circumstances :
if slow ventricular rate < 40 bpm:
- with-hold AV nodal blocking agents
- consider atropine, temporary pacing
rapid rate, haemodynamically unstable due to the AF, or has WPW
- emergent DC reversion:
- sedate
- synch 150-200J biphasic DC reversion (if WPW, ensure defibrillator is detecting QRS and not the T wave otherwise you may get VF! Consider using different lead to detect QRS complexes)
- if fails and not WPW or aberrancy, give amiodarone 5mg/kg iv over 10-20 minutes, then attempt DC reversion again
- continue amiodarone infusion for 24hrs
rapid ventricular rate (>120bpm) but patient stable:
- (i) pre-excitation syndrome such as WPW:
- avoid AV nodal blockers such as digoxin, amiodarone, beta adrenergic blockers and calcium channel blockers
- consider DC reversion or consider class Ia, Ic
- (ii) cardiac failure and poor cardiac function:
- amiodarone 5mg/kg iv
- or consider IV diltiazem if cardiac failure not too severe and not hypotensive
- avoid negative inotropes such as verapamil and beta adrenergic blockers
- (iii) most other patients
- consider a beta blocker such as:
- metoprolol 25 mg tds po or 5mg iV (repeat if necessary)
- (IV esmolol if worried about risk of beta blockers as short acting)
- (some favour sotalol 80mg bd orally)
- C/I: asthma/COPD, uncontrolled heart failure, sick sinus syndrome, heart block, hypotension, severe peripheral vascular disease (PVD or PAD)
- or a calcium channel blockers such as:
- verapamil (Isoptin) 40 mg tds po or 5 mg iV
- C/I: heart failure, hypotension, sick sinus syndrome, heart block, AF with WPW, VT, pregnancy & breast-feeding
- or amiodarone 5mg/kg iv
- (iv) consider pharmacologic cardioversion if AF duration < 48hrs and age < 50 and no structural heart disease:
- ie. “lone AF”
- NB. ~60% with paroxysmal AF will revert without drugs or DC reversion
- avoid calcium channel blockers in this group as it tends to prolong duration of AF - see here
- young adult, no underlying structural cardiac disease
- flecainide 200-400mg orally or 2mg/kg IV (max 150mg) over 10 mins can be used as it is more effective than amiodarone in expediting reversion (~80% vs 40-60% at 8hrs while placebo had ~40% reversion)
- flecainide is C/I in LV systolic dysfunction and probably should NOT be used unless echocardiogram first.
- 10% develop hypotension or bradycardia if use 2mg/kg dose
- other patients
- amiodarone 5mg/kg IV over 60min but this is controversial
semi-elective DC cardioversion:
- if still in AF at 24-48hrs post onset then consider admitting for semi-elective DC reversion if < 48hrs duration:
- discuss with cardiology
- it may be that a -ve D-Dimer may assist in selecting pts safe to DC revert - see here
- for every 100 pts with AF > 48hrs, 66 would avoid the need for TOE or anticoagulation at the cost of 1 pt having a false negative for mural thrombus.
- S/C clexane then warfarin if AF duration likely to be > 24-48hrs
- fast patient prior to sedation/short GA
- synchronised DC
- 100J, step up to 360J in increments as needed
- monitor ECG, vitals for at least 1 hour after
haemodynamically stable with minimal symptoms and ventricular rate 50-120:
- if paroxysmal AF in patient < 50yrs and no structural heart disease:
- consider no therapy as most will revert spontaneously within 24hrs (Am J Cardiol 1995 75:693-697)
- ⇒ consider metoprolol for rate control
- ⇒ consider clexane S/C
- ⇒ once underlying causes excluded, discharge home for LMO or cardiology R/V within 48hrs of onset of AF & if still present then patient will need to be considered for:
- semi-elective cardioversion if duration <48hrs
- otherwise, ongoing anticoagulation, rate control +/- elective cardioversion
- otherwise (eg. persistent or permanent AF, or known IHD, valvular heart disease or over 50yrs):
- check adequate long term rate control and reassess risk/benefits of anticoagulation
- long term rate control:
- digoxin - not as good for exercise-induced AF; but useful in the elderly and those with cardiac failure;
- metoprolol - better for exercise-induced AF, better rate control than amiodarone and digoxin and safer than sotalol which has risk of torsades.
- post-cardioversion:
- if AF duration was > 48hrs, anticoagulation is continued for 4 weeks after cardioversion as atrial stunning may persist
- risk of relapse of AF after cardioversion is high without antiarrhythmic drugs which are particularly of benefit in the first 3 months if an identifiable cause has been corrected.
- percentage of patients remaining in SR if no antiarrhythmics
- 69% at 1 month
- 58% at 6 months
- 23% at 1 year
- 16% at 2 years.
- with prophylactic antiarrhythmic therapy up to 80% will still be in SR at 12 months, even with a dilated LA as long as no other poor prognostic factors are present:
- the risks of long term anti-arrhythmics such as sotalol or amiodarone for recurrent AF probably outweighs the benefit and for most patients a rate controlling agent +/- warfarin is preferred.
disposition:
- admission is usually only warranted if:
- ongoing haemodynamic instability
- unable to get ventricular rate < 110/minute for 2hrs
- unable to mobilise to usual level
- cardiac failure
- disturbing symptoms
- other issues that mandate admission
- ideally for lone AF patients with persistent AF (no structural heart disease or risk factors and new AF):
- review in 24hrs for a transthoracic echocardiogram to exclude structural abnormalities and check rhythm status then decide on need for long term anticoagulation.
- unfortunately, TTE availability is often substantially delayed so referral and OP cardiology consult is reasonable +/- anticoagulation in the interim if patient is in the higher risk categories for stroke or if there is a possibility cardiology will perform semi-elective DC cardioversion.
c_af_mxdetails.txt · Last modified: 2018/12/23 10:57 by 127.0.0.1