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
- 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