From the Research
The lowest effective dose of metoprolol for prevention of atrial fibrillation (AF) with rapid ventricular response is typically 25-50 mg twice daily, with titration based on patient response, as supported by the most recent and highest quality study 1.
Key Considerations
- The initial dose may be lower (12.5-25 mg twice daily) in elderly patients or those with hepatic impairment.
- For optimal effectiveness, the dose can be gradually increased to a maximum of 100-200 mg daily, divided into two doses, while monitoring heart rate and blood pressure.
- When initiating therapy, patients should be closely monitored for bradycardia, hypotension, and heart failure symptoms.
Mechanism and Efficacy
- Metoprolol works by blocking beta-1 adrenergic receptors in the heart, reducing sympathetic stimulation, which slows heart rate and decreases cardiac contractility.
- This mechanism helps control ventricular rate during AF episodes and may reduce the frequency of AF recurrences.
- The extended-release formulation (metoprolol succinate) may be preferred for once-daily dosing to improve adherence.
Comparison with Other Agents
- A recent systematic review and meta-analysis found that metoprolol was associated with a 26% lower risk of adverse events compared to diltiazem for AF with rapid ventricular rate 1.
- However, there was no difference in rates of bradycardia or hypotension between the two agents.
Monitoring and Follow-up
- Regular follow-up is essential to assess efficacy and adjust dosing as needed, with the goal of maintaining heart rate control while minimizing side effects.
- Patients should be monitored for signs of heart failure, bradycardia, and hypotension, and the dose adjusted accordingly.