Atrial fibrillation (main)

Background

Atrial fibrillation (AF) categories:

• First detected episode
• Recurrent (after 2 or more episodes)
• Paroxysmal (if recurrent AF terminates spontaneously)
• Persistent (if sustained beyond 7 days)

Causes:

• Cardiac (atrial enlargement)
  • Hypertension
  • Ischemic heart disease
  • Rheumatic heart disease
• Noncardiac (increased automaticity)
  • Thyrotoxicosis
  • Chronic lung disease
  • Pericarditis
  • Ethanol ("holiday heart")
  • PE
  • Drugs (cocaine, TCA)

Clinical Features

1. Asymptomatic - 44%
2. Palpitations - 32%
3. Dyspnea - 10%
4. Stroke - 2%
5. Also can present with decompensated heart failure, acute pulmonary edema

Diagnosis

• 3 patterns on ECG:

1. Typical
   1. Irregularly, irregular R waves
   2. QRS rate 140-160/min
2. Large fibrillatory waves
   1. May look like flutter waves
      1. Unlike a-flutter, the fibrillatory waves are irregular
3. Slow, regular A-fib
   1. Due to complete AV block with escape rhythm

• Ischemic changes?
• Rate > 250? (think preexcitation)

Work-Up

1. ECG
2. Digoxin level (if appropriate)
3. Chem-10
4. TSH & free T4 (AF increased in subclinical hyperthyrodism)

Special cases:

• Eval for ACS/MI
  • In pt with ECG changes, hypotension, angina
    • AF is rarely only manifestation of ACS, although RVR and hypotension can provoke demand ischemia

Treatment

• Rate control
  • See: Atrial Fibrillation (RVR)
• Anti-thrombotic therapy
  • Chronic and paroxysmal a fib are associated with thrombus formation

CHADS2 Score

1. CHF (1pt)
2. HTN (1pt)
3. Age>75 (1pt)
4. DM (1pt)
5. Stroke/TIA (2pts)

• Score 0: consider no treatment or ASA
• Score 1: consider warfarin or ASA
• Score 2-6: consider warfarin (INR goal = 2-3)
• All patients with valvular disease should be on anticoagulation

Disposition

• Consider discharge for paroxysmal A-fib successfully treated if none of the following:
  • Hemodynamic instability
  • Myocardial ischemia
  • CHF exacerbation
  • Symptomatic recurrence in the ED

Complications

1. Hemodynamic compromise
   1. A-fib lowers CO by 20-30%
   2. Impaired coronary blood flow
2. Arrhythmogenesis
3. Arterial thromboembolism

See Also

• Atrial Fibrillation (RVR)
• ACLS (Main)

Source

• UpToDate
• Annals of EM; Jan 2011. 57(1)