What medications are used to prevent atrial fibrillation (AFib)?

Medications Used to Prevent Atrial Fibrillation

Beta-blockers are the first-line medications recommended to prevent atrial fibrillation, particularly after cardiac surgery and in patients with hypertension or structural heart disease. 1

Primary Prevention Strategy: Beta-Blockers

Beta-blockers (Vaughan Williams Class II agents) are the preferred initial therapy for AF prophylaxis with substantial net benefit and the lowest risk profile compared to other antiarrhythmic agents. 1

Specific Beta-Blocker Options and Dosing:

• Metoprolol tartrate: 2.5-5 mg IV bolus over 2 minutes (up to 3 doses); oral maintenance 25-100 mg twice daily 1, 2
• Metoprolol succinate (extended-release): 50-400 mg once daily 1, 2
• Atenolol: 25-100 mg once daily 1
• Bisoprolol: 2.5-10 mg once daily 1
• Carvedilol: 3.125-25 mg twice daily 1

Why Beta-Blockers Are Preferred:

• Proven efficacy in preventing post-cardiac surgery AF with strength of recommendation A 1
• Very low proarrhythmic risk compared to other antiarrhythmic classes 1, 3
• Mortality benefit in patients with heart failure and post-myocardial infarction 3, 4
• Effective for both rhythm maintenance and rate control during AF episodes 3, 5

Second-Line Antiarrhythmic Agents

When beta-blockers are contraindicated or insufficient, the following agents should be considered based on cardiac structure and function:

For Patients WITHOUT Structural Heart Disease:

Flecainide and propafenone (Class IC agents) are recommended as first-line rhythm control options in structurally normal hearts. 1, 6

• Flecainide: Effective for preventing recurrent AF with low proarrhythmic risk in normal hearts 1
• Propafenone: Similar efficacy to flecainide 1
• Critical contraindication: Must avoid in patients with ischemic heart disease or heart failure due to risk of life-threatening ventricular arrhythmias 1, 6
• Important caveat: Pre-administer a beta-blocker, verapamil, or diltiazem to prevent high ventricular rates from AF converting to atrial flutter with 1:1 conduction 1

Dronedarone is also recommended for patients without structural heart disease:

• Maintains sinus rhythm and reduces cardiovascular hospitalizations 1
• Absolute contraindications: Recently decompensated heart failure or permanent AF (increases mortality in these populations) 1

Sotalol (Class III agent) may be considered:

• Requires careful evaluation of proarrhythmic risk, particularly in elderly patients with structural heart disease, renal insufficiency, or concurrent diuretic use 1
• Risk of torsades de pointes is approximately 1% 1

For Patients WITH Structural Heart Disease (Heart Failure, LV Hypertrophy, Ischemic Heart Disease):

Amiodarone is the recommended antiarrhythmic agent when beta-blockers are contraindicated or when patients have structural heart disease. 1

• Most effective multichannel blocker with low proarrhythmic risk 1
• Safe in heart failure patients, including those with reduced ejection fraction 1, 7
• Major limitation: Frequent extracardiac side-effects (thyroid, pulmonary, hepatic, ocular) especially with long-term therapy, making it a second-line choice when other agents are suitable 1
• Monitoring required: QT interval and TU waves should be monitored; torsades de pointes can occur 1

Dofetilide is an alternative Class III agent:

• Effective for rhythm control 1
• Requires inpatient initiation with continuous ECG monitoring due to proarrhythmic risk 1

Agents NOT Recommended for AF Prevention

The following medications should NOT be used for AF prophylaxis:

• Calcium channel antagonists (verapamil, diltiazem): Not effective for preventing AF after cardiac surgery (strength of recommendation D) 1
• Magnesium: Not recommended for routine AF prevention (strength of recommendation D) 1
• Digitalis monotherapy: Not recommended for reducing AF incidence (strength of recommendation I) 1
• Quinidine and disopyramide: Associated with increased all-cause mortality (OR 2.39) at 1-year follow-up, likely due to torsades de pointes 1, 6

Clinical Decision Algorithm

Step 1: Assess Cardiac Structure and Function

• No structural heart disease (no heart failure, no significant LV hypertrophy, no ischemic heart disease): Proceed to Step 2A
• Structural heart disease present (heart failure, LV hypertrophy, ischemic heart disease, prior MI): Proceed to Step 2B

Step 2A: For Structurally Normal Hearts

1. First choice: Flecainide or propafenone (with concurrent beta-blocker for rate control) 1
2. Alternative first choice: Dronedarone 1
3. Second choice: Sotalol (if proarrhythmic risk is acceptable) 1
4. Third choice: Amiodarone (if other agents fail or are not tolerated) 1

Step 2B: For Structural Heart Disease

1. First choice: Beta-blocker (if not already on one) 1, 3
2. Second choice: Amiodarone (if beta-blocker contraindicated or insufficient) 1
3. Alternative: Dofetilide (requires inpatient initiation) 1
4. Avoid: Class IC agents (flecainide, propafenone) due to increased risk of sustained ventricular arrhythmias 1, 6

Special Populations

Post-Cardiac Surgery:

• Beta-blockers are strongly recommended for AF prophylaxis (strength of recommendation A) 1
• Reinstate beta-blockers in patients receiving long-term therapy prior to surgery 1

Hypertrophic Cardiomyopathy:

• Amiodarone or disopyramide combined with a beta-blocker or non-dihydropyridine calcium channel antagonist are reasonable 1
• Disopyramide may reduce LV outflow gradient and improve symptoms 1

Thyrotoxicosis:

• Beta-blockers are first-line to control ventricular rate unless contraindicated 1
• Non-dihydropyridine calcium channel antagonist if beta-blockers cannot be used 1

Chronic Obstructive Pulmonary Disease:

• Non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) are first-line 1, 2
• Beta-1 selective blockers (bisoprolol) in small doses may be considered as alternative 2

Common Pitfalls to Avoid

Critical safety considerations:

1. Never use Class IC agents (flecainide, propafenone) in patients with ischemic heart disease or heart failure - this significantly increases risk of life-threatening ventricular arrhythmias 1, 6

2. Never use amiodarone, adenosine, digoxin, or calcium channel blockers in Wolff-Parkinson-White syndrome with pre-excited AF - these drugs accelerate ventricular rate and are potentially harmful 1

3. Avoid dronedarone in patients with recently decompensated heart failure or permanent AF - increases mortality in these populations 1

4. Monitor QT interval carefully with Class III agents (sotalol, dofetilide, amiodarone) - risk of torsades de pointes, especially in elderly, with renal insufficiency, hypokalemia, or concurrent diuretics 1

5. Always pre-treat with AV nodal blocking agents (beta-blockers, calcium channel blockers) before starting flecainide or propafenone - prevents dangerous 1:1 atrial flutter conduction 1