Regarding the mechanisms and management of atrial fibrillation, all of the following statements are correct EXCEPT:

Question

Accepted Answer

C. Amiodarone is the most effective antiarrhythmic for rhythm control and should be first-line therapy in all patients with paroxysmal AF. ## Mechanism of Atrial Fibrillation & Management Principles

### Correct Statements (Options 0, 1, 3)

**Key Point:** Atrial fibrillation increases thromboembolic stroke risk approximately 4–5 fold due to blood stasis in the dilated left atrium and reduced atrial contractility. Anticoagulation decisions are guided by CHA₂DS₂-VASc scoring, with a threshold of ≥1 in males and ≥2 in females for oral anticoagulant therapy [cite:Harrison 21e Ch 226].

**High-Yield:** The AFFIRM trial and subsequent evidence demonstrate that rate control (target resting HR <110 bpm in stable AF) is non-inferior to rhythm control for symptom relief and mortality, and is preferred in most haemodynamically stable patients. Beta-blockers and non-dihydropyridine CCBs (diltiazem, verapamil) are first-line agents for rate control.

**Clinical Pearl:** Atrial fibrillation is both a cause and consequence of structural remodelling. Left atrial enlargement (>40 mm) and electrical remodelling (shortened atrial refractory period due to altered calcium handling and ion channel expression) perpetuate the arrhythmia—a phenomenon termed "AF begets AF."

### Why Option 2 is INCORRECT

**Warning:** Amiodarone is a potent antiarrhythmic with high efficacy for rhythm control, but it is NOT first-line for all patients with paroxysmal AF due to:
- Significant extracardiac toxicity (thyroid, liver, pulmonary, neurologic)
- Proarrhythmic potential (torsades de pointes)
- Drug–drug interactions
- Slow onset of action (days to weeks)

**High-Yield:** First-line rhythm control agents for paroxysmal AF are:
1. Flecainide or propafenone (in structurally normal hearts)
2. Sotalol (if structural disease present)
3. Amiodarone is reserved for refractory cases or those with significant structural/systemic disease [cite:Harrison 21e Ch 226].

### Summary Table: Antiarrhythmic Selection in AF

| Agent | Indication | Key Advantage | Key Limitation |
| --- | --- | --- | --- |
| Flecainide/Propafenone | Paroxysmal AF, structurally normal heart | Rapid onset, oral | Contraindicated in CAD/LV dysfunction |
| Sotalol | Structural disease, paroxysmal or persistent | Beta-blocker + Class III | QT prolongation, torsades risk |
| Amiodarone | Refractory AF, haemodynamic instability | Most effective | Extracardiac toxicity, slow onset |
| Beta-blockers/CCBs | All AF (rate control) | Safety, tolerability | Less effective for rhythm control |

Answer

A. Rate control using beta-blockers or non-dihydropyridine calcium channel blockers is preferred over rhythm control in most patients with haemodynamically stable AF

Answer

B. Atrial fibrillation is associated with left atrial enlargement, and electrical remodelling shortens the atrial refractory period, perpetuating the arrhythmia

Answer

D. Atrial fibrillation increases stroke risk 4–5 fold, and anticoagulation is indicated based on CHA₂DS₂-VASc score ≥1 in males and ≥2 in females

Regarding the mechanisms and management of atrial fibrillation, all of the following statements are correct EXCEPT:

Explanation

Practice similar questions