Atrial fibrillation (A-Fib) is the most common sustained cardiac arrhythmia, affecting millions worldwide. It is characterized by uncoordinated electrical activity in the atria, leading to rapid, irregular contractions. Instead of contracting effectively, the atria quiver, which increases the risk of blood clot formation and life-threatening complications like stroke.
What is Atrial Fibrillation?
Normally, the sinoatrial (SA) node generates rhythmic impulses that travel through the atria, producing coordinated atrial contractions.
In A-Fib, electrical impulses arise chaotically from multiple sites in the atria. This causes:
- Irregular atrial activity (“fibrillation waves”)
- Loss of effective atrial contraction
- Irregular ventricular response, leading to an irregular heartbeat
Key Point: The hallmark of A-Fib is an irregularly irregular rhythm with no distinct P waves on the EKG.
EKG Features of A-Fib
- Rate: Usually >100 bpm (can be slower with treatment or in chronic cases)
- Rhythm: Irregularly irregular
- P waves: Absent; replaced by fibrillatory (f) waves
- PR interval: Not measurable
- QRS complex: Narrow, normal (unless bundle branch block or pre-existing conduction abnormality)
On EKG, the absence of P waves and varying R-R intervals are diagnostic clues.
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Causes of Atrial Fibrillation
A-Fib can develop due to multiple cardiac and systemic conditions:
1. Cardiac Causes
- Heart failure
- Ischemic heart disease (coronary artery disease, prior myocardial infarction)
- Hypertension (most common cause)
- Valvular heart disease (especially mitral stenosis or regurgitation)
- Post-cardiac surgery
2. Non-Cardiac Causes
- Chronic obstructive pulmonary disease (COPD)
- Hyperthyroidism (thyrotoxic atrial fibrillation)
- Obesity and sleep apnea
- Elderly patients have higher incidence
- Family history
- Excess alcohol (“holiday heart syndrome”)
Clinical Manifestations
Many patients with A-Fib are asymptomatic, but when symptoms do occur, they result from inefficient atrial contraction and reduced cardiac output.
Common Symptoms:
- Fatigue and malaise
- Dizziness or lightheadedness
- Shortness of breath
- Tachycardia (rapid heartbeat)
- Palpitations (fluttering or irregular heartbeat)
- Anxiety
Important: Some patients may only present with stroke or systemic embolism as the first sign of underlying A-Fib.
Complications of A-Fib
The most dangerous consequence of atrial fibrillation is thromboembolism.
Blood pooling in the atria (due to quivering instead of contracting) leads to clot formation.These clots can embolize, causing:
- Stroke (cerebrovascular accident)
- Myocardial infarction (MI)
- Pulmonary embolism (PE)
- Deep vein thrombosis (DVT)
Patients with A-Fib are 5 times more likely to suffer a stroke compared to the general population.
Treatment of Atrial Fibrillation
Management depends on whether the patient is stable or unstable and focuses on three principles:
Rate Control
- Beta blockers (Metoprolol)
- Calcium channel blockers (Diltiazem, Verapamil)
- Digoxin (less commonly, especially in elderly or sedentary patients)
Rhythm Control
- Antiarrhythmic medications (Amiodarone, Sotalol, Flecainide)
- Electrical cardioversion (synchronized shock to restore sinus rhythm)
Anticoagulation (to prevent clots)
- Warfarin (monitored via INR)
- Direct Oral Anticoagulants (DOACs: Apixaban, Rivaroxaban, Dabigatran)
Stable Patient
- Oxygen therapy
- Drug therapy for rate/rhythm control
- Long-term anticoagulation to prevent stroke
Unstable Patient (severe hypotension, chest pain, shock)
- Oxygen therapy
- Immediate synchronized cardioversion
- Follow-up anticoagulation
Defibrillation is NOT used in A-Fib (reserved for pulseless VT/V-Fib).
Cardioversion in A-Fib
Cardioversion is often performed in patients with new-onset or symptomatic A-Fib. However, risk of embolization must be considered:
- If A-Fib >48 hours, anticoagulation for at least 3 weeks before cardioversion is recommended.
- Alternatively, a transesophageal echocardiogram (TEE) can be performed to rule out atrial thrombus before immediate cardioversion.
Comparative Overview: A-Fib vs V-Fib
| Feature | Atrial Fibrillation (A-Fib) | Ventricular Fibrillation (V-Fib) |
|---|---|---|
| Origin | Atria | Ventricles |
| Rhythm | Irregularly irregular | Chaotic, irregular |
| P waves | Absent, fibrillatory waves | Absent |
| QRS complex | Normal, narrow | Not visible |
| Clinical Impact | Stroke risk, heart failure | Immediate cardiac arrest |
| Treatment | Rate/rhythm control + anticoagulation | Immediate defibrillation + CPR |
Frequently Asked Questions (FAQ)
Q1. Can A-Fib go away on its own?
Yes. This is called paroxysmal A-Fib. Episodes may stop spontaneously but often recur, requiring long-term management.
Q2. Is A-Fib the same as a heart attack?
No. A-Fib is an arrhythmia (electrical problem), while a heart attack is due to blocked blood flow. However, A-Fib increases the risk of heart attack.
Q3. What lifestyle changes help manage A-Fib?
Weight control, reducing alcohol and caffeine, treating hypertension, managing sleep apnea, and avoiding stimulants can all help.
Q4. What is the difference between cardioversion and defibrillation in A-Fib?
- Cardioversion: Synchronized shock used in unstable A-Fib.
- Defibrillation: Asynchronous high-energy shock used in pulseless VT or V-Fib, not in A-Fib.
Q5. Can anticoagulants cure A-Fib?
No. They don’t stop the arrhythmia but prevent life-threatening clots and strokes.
