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c_af_mxdetails

Detailed Mx of AF in the ED

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:
        • 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:
      • 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:
  • 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:
  • (ii) cardiac failure and poor cardiac function:
  • (iii) most other patients
  • (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 21:57 (external edit)