Atrial fibrillation (main)

Background

Causes

• Cardiac (atrial enlargement)
  • HTN, CAD, valvular disease, cardiomyopathy, ACS
• Noncardiac (increased automaticity)
  • Hyperthyroidism, PE, hypoxic pulmonary conditions, ethanol ("holiday heart"), drugs (cocaine, TCA)
  • Need to treat underlying cause

Complications

• Hemodynamic compromise
  • Lowers CO by 20-30%
  • Impaired coronary blood flow
• Arrhythmogenesis
• Arterial thromboembolism

Diagnosis

• Presentation
  • Asymptomatic - 44%
  • Palpitations - 32%
  • Dyspnea - 10%
  • Stroke - 2%
  • Also can present with decompensated heart failure, acute pulmonary edema
• History
  • History of afib?
    • If yes, on medication?
    • If no, was the onset recgonized?
  • <48hrs duration?
• Physical Exam
  • Evidence of hemodynamic instability, CHF?
• ECG (3 types)
  • Typical
    • Irregularly, irregular R waves
    • QRS rate 140-160/min
  • Large fibrillatory waves
    • May look like flutter waves
      • Unlike a-flutter, the fibrillatory waves are irregular
  • Slow, regular A-fib
    • Due to complete AV block with escape rhythm
  • Ischemic changes?
  • Rate > 250? (think preexcitation)

Work-Up

• ECG
• Digoxin level (if appropriate)
• Chem-10
• TSH

Treatment

• See Atrial Fibrillation (RVR)
• Anti-thrombotic therapy
  • Chronic and paroxysmal a fib are associated with thrombus formation
  • Decision based on CHADS2 Score
    • Chf (1pt)
    • HTN (1pt)
    • Age>75 (1pt)
    • DM (1pt)
    • Stroke/TIA (2pts)
  • Score 0 - consider no treatment or ASA
  • Score 1 - consider coumadin or ASAn
  • Score 2-6 - consider coumadin (INR goal = 2-3)
  • All patients with valvular disease should be on anticoagulation

Cardioversion

• If unstable OR low risk for clot (risk still about 1%)
  • Low Risk = <48 hrs symptoms, new dx, no hx similar episodes, no cause found by history, no LV dysfunction, no mitral valve dz, no prior thromboembolic event
• Then anticoagulation for 3 weeks afterward

Chemical Cardioversion

Ibutilide (Class III)

1 mg over 10 min in pts >60 kg (or 0.01 mg/kg)

can repeat dose once if not sinus within 10 min of infusion

Avoid in hypoK, hypoMg, prolonged QT, torsades

Efficacy superior at 90 min to IV procainamide /sotalol

(monitor for few hours for polymorph VT (8% incidence), then d/c home with PO beta/Ca blockers)

Other Options:

Procainamide up to 1 gm IV (100 mg Q5 min) @ <20 mg/min

Amiodarone 0.75 mg/kg IV over 15 min. 1200 mg in 24h

Flecainide 300mg po

Disposition

• New-Onset Afib (<48hrs)
  • If stable, no history of heart disease, no other indication for admission then most patients can be directly d/c'd from the ED after successful pharmacologic or electrical cardioversion
    • Outpatient TTE, cardiology follow-up
• In the absence of angina, ECG evidence of MI, or recent infarction, no need to admit to r/o MI!
• Indications for hospitalization:
  • Hemodynamic instability
  • Myocardial ischemia
  • CHF exacerbation 2/2 a-fib
  • Symptomatic recurrence in the ED

See Also

Atrial Fibrillation (RVR)==

Source

1/30/06 DONALDSON (adapted from Lampe), UpToDate