What are the medications and dosing for atrial fibrillation?

Medications and Dosing for Atrial Fibrillation

The primary medications for atrial fibrillation include rate control agents (beta blockers, calcium channel blockers, digoxin), rhythm control agents (antiarrhythmics), and anticoagulants (direct oral anticoagulants and warfarin), with dosing based on specific patient factors including renal function, age, and weight. 1

Anticoagulation Therapy

Direct Oral Anticoagulants (DOACs)

DOACs are generally preferred over warfarin due to lower bleeding risks and no need for regular monitoring 2.

Apixaban

• Standard dose: 5 mg twice daily 1, 3
• Reduced dose (2.5 mg twice daily) if patient has at least 2 of:
  • Age ≥80 years
  • Body weight ≤60 kg
  • Serum creatinine ≥1.5 mg/dL 1, 3
• Can be used in patients with CrCl <15 mL/min or on dialysis 1

Dabigatran

• Standard dose: 150 mg twice daily (CrCl >30 mL/min) 1
• Reduced dose: 75 mg twice daily (CrCl 15-30 mL/min) 1
• Contraindicated in CrCl <15 mL/min or dialysis 1

Rivaroxaban

• Standard dose: 20 mg once daily with food (CrCl >50 mL/min) 1, 4
• Reduced dose: 15 mg once daily with food (CrCl 15-50 mL/min) 1, 4

Edoxaban

• Standard dose: 60 mg once daily (CrCl 51-95 mL/min) 1
• Reduced dose: 30 mg once daily (CrCl 15-50 mL/min) 1
• Contraindicated if CrCl >95 mL/min or <15 mL/min 1

Warfarin

• Dose adjusted to maintain INR 2.0-3.0 1
• Higher target (INR 2.5-3.5) may be appropriate for patients with mechanical heart valves 1

Rate Control Medications

Beta Blockers

• Metoprolol tartrate: 25-200 mg twice daily (IV: 2.5-5 mg bolus over 2 min, up to 3 doses) 1
• Metoprolol succinate: 50-400 mg daily or divided twice daily 1
• Atenolol: 25-100 mg daily (renally eliminated) 1
• Bisoprolol: 2.5-10 mg daily 1
• Carvedilol: 3.125-25 mg twice daily 1
• Esmolol (IV only): 500 μg/kg bolus over 1 min, then 50-300 μg/kg/min 1
• Nadolol: 10-240 mg daily 1
• Propranolol: 10-40 mg 3-4 times daily (IV: 1 mg over 1 min, repeat as needed every 2 min, up to 3 doses) 1

Calcium Channel Blockers (Non-dihydropyridine)

• Diltiazem: 120-360 mg daily (extended release)
  • IV: 0.25 mg/kg over 2 min, may repeat 0.35 mg/kg over 2 min, then 5-15 mg/h continuous infusion 1
  • Avoid in heart failure with reduced ejection fraction (HFrEF) 1
• Verapamil: 180-480 mg daily (extended release)
  • IV: 5-10 mg over ≥2 min (may repeat twice), then 5 mg/h continuous infusion (max 20 mg/h) 1
  • Avoid in HFrEF 1

Digitalis Glycoside

• Digoxin: 0.0625-0.25 mg daily
  • IV: 0.25-0.5 mg over several min, repeat doses of 0.25 mg every 6 hours 1
  • Renally eliminated
  • Increased mortality at plasma concentrations exceeding 1.2 ng/mL 1

Rhythm Control Medications (Antiarrhythmics)

For Cardioversion

Amiodarone

• Oral loading: 600-800 mg daily in divided doses to total load of 10 g, then 200 mg daily maintenance 1
• IV: 150 mg over 10 min, then 1 mg/min for 6 h, then 0.5 mg/min for 18 h or change to oral dosing 1

Dofetilide (requires hospitalization for initiation)

• Based on CrCl (mL/min):

  • 60: 500 mcg twice daily

  • 40-60: 250 mcg twice daily
  • 20-40: 125 mcg twice daily
  • <20: Not recommended 1

Flecainide

• Oral: 200-300 mg single dose 1
• Avoid in patients with coronary artery disease or significant structural heart disease 1
• Give with beta blocker or calcium channel antagonist 1

Propafenone

• Oral: 450-600 mg single dose 1
• Avoid in patients with coronary artery disease or significant structural heart disease 1
• Give with beta blocker or calcium channel antagonist 1

Ibutilide (IV only)

• 1 mg over 10 min; may repeat 1 mg once if necessary
• For weight <60 kg: use 0.01 mg/kg 1

Special Considerations

Perioperative Management

For patients requiring surgery with anticoagulation interruption 1:

Low Bleeding Risk Procedures

• Apixaban (CrCl >25 mL/min): Hold for 1 day
• Dabigatran (CrCl >50 mL/min): Hold for 1 day
• Dabigatran (CrCl 30-50 mL/min): Hold for 2 days
• Edoxaban (CrCl >15 mL/min): Hold for 1 day
• Rivaroxaban (CrCl >30 mL/min): Hold for 1 day
• Warfarin: Hold for 5 days (target INR <1.5)

High Bleeding Risk Procedures

• Apixaban: Hold for 2 days
• Dabigatran (CrCl >50 mL/min): Hold for 2 days
• Dabigatran (CrCl 30-50 mL/min): Hold for 4 days
• Edoxaban: Hold for 2 days
• Rivaroxaban: Hold for 2 days
• Warfarin: Hold for 5 days

Hypertrophic Cardiomyopathy with AF

• Anticoagulation is indicated regardless of CHA₂DS₂-VASc score 1
• For rhythm control, amiodarone or disopyramide (combined with beta blockers or calcium channel antagonists) are reasonable options 1

Common Pitfalls and Caveats

1. DOAC Dosing Errors: Ensure proper dose adjustment based on renal function, age, and weight to prevent bleeding complications or thrombotic events 1

2. Drug Interactions:

   • Combined P-gp and strong CYP3A4 inhibitors increase apixaban levels (reduce dose or avoid) 3
   • Combined P-gp and strong CYP3A4 inducers reduce apixaban levels (avoid concomitant use) 3

3. Renal Function Monitoring: Regular monitoring of renal function is essential, especially in elderly patients or those with fluctuating renal function 1

4. Antiarrhythmic Initiation: Some antiarrhythmics (e.g., dofetilide) require hospitalization for initiation due to risk of QT prolongation and torsades de pointes 1

5. Cardioversion Timing: For patients with AF ≥48 hours or unknown duration, anticoagulation should be given for ≥3 weeks prior to and 4 weeks after cardioversion 1