atrial fibrillation

see also:

• cardiology
• cardiac arrhythmias
• atrial flutter
• aetiology and pathophysiology of atrial fibrillation
• Pre-excitation syndrome such as WPW
• see Detailed Mx of the patient with AF in the ED

• prevalence of AF in western countries is 1-4% with 70% of those with AF being aged > 65yrs and incidence appears to be increasing worldwide due to improved detection ¹⁾
• it is a major risk factor for congestive cardiac failure and stroke (CVA) (see prognosis below)

• most patients who are haemodynamically stable can be managed with rate controlling agents ²⁾, observed until ventricular rate drops below 110-115 and are asymptomatic BUT with proviso that:
  • choice of rate controlling agent be tailored for the patient, especially if there is evidence of cardiac failure or sepsis in which case beta adrenergic blockers should be avoided as these may increase acute mortality
  • cause of rapid AF has been sort (eg. infection, ACS, hyperthyroidism, alcohol, etc)
  • consideration has been given to discharge on anticoagulants to prevent stroke
  • referral to cardiology for possible delayed DC cardioversion at either 48hrs or 3 wks
  • patient education is provided
    • approx. 2/3rd of those with acute AF given rate control will have spontaneous reversion within 48hrs
    • there are no significant clinical outcome differences between a wait and see rate control approach vs early ED DC reversion in this group
    • stroke risk

• DC revert if either:
  • haemodynamically unstable due to AF - NB. most instances of instability are not actually due to the AF!
  • wide complex tachycardia
  • perhaps if pre-excitation syndrome such as WPW as digoxin may be lethal in WPW and beta blockers and calcium blockers should be avoided
  • perhaps if AF duration 36-48hrs AND patient is already on long term anticoagulation or have a low risk for stroke
  • perhaps if new lone AF < 48hrs duration
    • but as there is a risk of stroke, and many will spontaneously revert anyway, thus it should be a shared decision with the patient
    • stroke risk with DC reversion:
      • <12hr duration and lone AF = 0.3%
      • 12-48hr duration and lone AF = 1.1%
      • <48hrs duration but with heart failure, diabetes and older patient = 8-9% thus do not DC revert these patients unless life threatening AF
      • at 3wks with anticoagulant cover = 0.3-0.8%
• DC reversion works 90% of cases but in addition to stroke risk, there is 1% risk of VT

• if no significant heart failure:
  • metoprolol 25 mg tds po or 5mg iV (repeat if necessary)
  • OR verapamil (Isoptin) 40 mg tds po or 5 mg iV
• OTHERWISE use amiodarone 5mg/kg IV (recommended for patients with co-existing heart failure)
• if narrow complex with cardiac failure, consider digoxin

• if mod-high risk of thromboembolism which outweighs risk of warfarin (ie. avoid if very old or other risk of bleeding), then start warfarin Rx.
  • ie. if CHADS2 score = 2 or more and no C/I to warfarin
• if warfarin risk not acceptable, clopidogrel plus aspirin (acetylsalicylic acid) 75mg o daily is more effective than aspirin alone but does increase bleeding risk³⁾
• see antithrombotic Rx for prevention of stroke

• ie. age < 60yrs, no structural heart disease, no pre-excitation syndrome such as WPW
• probably do not warrant DC or pharmacologic cardioversion, or anticoagulation as most will revert spontaneously, however, depending upon clinican and patient preferences, options include:
  • elective DC reversion, or,
  • iv amiodarone 5mg/kg over 30 minutes, or,
  • procainamide, or,
  • flecainide 2mg/kg IV (max 150mg) over 10 mins, or,
  • flecainide 200-400mg orally, or,
  • stat enoxaparin, and await spontaneous reversion, if this does not occur by the next day then either DC revert or refer for outpatient echo and cardiology opinion for possible elective reversion at 3wks with NOAC anticoagulant cover (if CHAD-VASC2 > 1 and no C/I to anticoagulants)
• probably do not need blood tests unless otherwise clinically indicated, but we still tend to do them as 4% will have thyroid disease.
• avoid verapamil (Isoptin) as tends to prolong AF duration
• avoid ongoing sotalol as increased risk of torsade de pointes VT and arrest
• avoid ongoing amiodarone and other anti-arrhythmic as many adverse effects and risks usually outweigh benefits
• if precipitated by excess vagal tone (during sleep, after spicy or cold food/drink, large meal distending stomach):
  • avoid digoxin as this may cause more episodes
  • advise against precipitants which increase vagal tone
  • consider beta blocker or disopyramide 300mg oral as a stat dose “pill-in-the-pocket” to terminate episode of AF ⁴⁾
• OP echo (TTE for risk stratification) and cardiology review

• patients who present to ED and have AF as a secondary problem have almost triple the 1 yr mortality and morbidity than those who just presented with AF ⁵⁾
• after presenting to ED in western countries, the 1 year all cause mortality is 5-10% and 10-20% will have stroke, embolism, myocardial infarction or require hospitalization for cardiac failure ⁶⁾
  • 30% of these died from congestive cardiac failure
  • 8% of these died from stroke (CVA)

• remove or manage precipitants such as hyperthyroidism
• Mx risks of thromoembolism (see above)
• rate controlling agents (see above)
  • long term vs prn
• drinking coffee
  • drinking coffee in the morning appears to reduce cardiovascular mortality by 30% ⁷⁾
  • drinking 2 cups a day appears to be beneficial for those with AF or in helping to prevent AF and cardiac failure
    • mildly reduces risk of AF in dose response manner although less than 2 cups a day appeared to mildly increase risk ⁸⁾
    • this study showed a 37% hazard reduction in AF recurrences ⁹⁾
    • appears to reduce risk of cardiac failure and major cardiovascular events (MACE) in patients with AF by ~26%¹⁰⁾
    • appears to reduce risk of dementia and improve cognition in those with AF and stroke although seems 3-5 cups a day of coffee or tea is needed, but more than 5 cups a day has been associated with increased risk in those with genetic risks of dementia ^11)12)13)
• catheter ablation may be suitable for some
  • those who have had successful catheter ablation of their AF no longer need anticoagulation after the 1st 12 months according to the 2025 OCEAN trial¹⁴⁾
  • it seems moderate weekly exercise of 90min/wk (eg. walking) is associated with nearly a 50% lower risk of AF recurrence following catheter ablation¹⁵⁾