Atrial fibrillation
From IDWiki
Definition
- A dysorganized and rapid atrial electrical activity leading to a loss of coordinated contraction of the atria and an irregularly irregular ventricular rhythm
- May be paroxysmal or persistent
Etiology
- Cardiac
- Hypertension
- Heart failure
- CAD
- Hypertrophic, dilated and restrictive cardiomyopathies
- Valvular heart disease
- Congenital heart disease
- Pericardial disease
- Post-surgical (particularly cardiac surgery)
- Sick sinus syndrome
- Atrial fibrillation as a result of ventricular pacing
- Supraventricular tachycardia
- Wolf-Parkinson White syndrome
- Atrial tachycardia
- Atrial flutter
- Genetic/Familial
- Non-cardiac
- Obstructive sleep apnea
- Obesity
- Excessive alcohol ingestion (acute or chronic)
- Hyperthyroidism
- Vagally-mediated (i.e. habitual aerobic training)
- Pulmonary disease
- Pneumonia
- COPD
- Pulmonary embolism
- Pulmonary hypertension
- Idiopathic
Acute Triggers
- Cardiac surgery or transplant
- Acute alcohol intoxication
- Acute illness including infection, myocardial infarction, or pulmonary embolism
- Hyperthyroidism
Pathophysiology
Differential Diagnosis
Epidemiology
- Prevalence by age 80 is approximately 10%
- Lifetime risk of developing AF for individuals 40 years old is approximately 25%
Risk Factors
- Age
- Hypertension
- Diabetes mellitus
- Cardiac disease
- Sleep apnea
Clinical Presentation
- Feeling of palpitations, acute or paroxysmal
- Syncope
- Examination
- Irregularly irregular heart rhythm
- Variable S1
Investigations
- Baseline: ECG, echo, CBC, coags, renal and liver function, TSH, lipids, and glucose
- Imaging
- CXR: to exclude lung disease and heart failure
- TEE: to rule out thrombus if planning cardioversion
- Labs
- Serum calcium and magnesium
- TSH
- Other
- Holter monitor or loop monitor: to capture paroxysmal atrial fibrillation when it is suspected
- Treadmill exercise test
- Electrophysiologic studies
- Sleep study: to rule out OSA
- Ambulatory blood pressure monitor
- Genetic testing
Management
- Cardioversion
- May cardiovert if onset within 12h or if anticoagulated for at least 3 weeks prior (and 4 weeks after cardioversion)
- Can consider cardioversion up to 48 hours if low-risk CHADS <2
- Rate control
- If atrial fibrillation with rapid ventricular response, may need rate control to target resting HR < 100
- Beta-blockers are first-line
- Metoprolol, starting at 25mg bid and titrating to effect
- Non-DHP CCBs are second-line
- Digoxin may be used in patients who are sedentary or have LV dysfunction
- Amiodarone is last-line
- Stroke prophylaxis
- ASA if low risk (CHADS2=0 or CHA2DS2-VASc<2)
- Warfarin, targeting an INR or 2-3
- Direct oral anticoagulants
Prognosis
- Risk of stroke by fivefold and is estimated to be the cause of 25% of strokes
