What is the best course of action for a patient status post (s/p) cardiac ablation for atrial fibrillation (afib) 4 months ago, now presenting with presyncope and sinus bradycardia, currently on flecainide (flecainide) 150mg twice a day (BID) and metoprolol (metoprolol) 6.25 mg BID?

Management of Bradycardia and Presyncope in Post-Ablation Patient on Flecainide and Metoprolol

Reduce or discontinue metoprolol and consider reducing flecainide dose to address symptomatic bradycardia and presyncope in this post-ablation patient. 1

Assessment of Current Situation

• The patient is experiencing presyncope with sinus bradycardia (51 BPM) 4 months after cardiac ablation for atrial fibrillation 1
• Current medications include flecainide 150mg BID and metoprolol 6.25mg BID 1
• This presentation suggests medication-induced bradycardia, a common side effect of both flecainide and beta-blockers 1

Immediate Management Steps

1. First-line approach: Reduce or discontinue metoprolol while maintaining flecainide therapy, as the beta-blocker is more likely contributing to the bradycardia while flecainide is essential for maintaining rhythm control post-ablation 1

2. If bradycardia persists after metoprolol adjustment: Consider reducing flecainide dose from 150mg BID to 100mg BID, as flecainide can also cause bradycardia and conduction disturbances 1, 2

3. Monitor the patient closely with ECG after medication adjustments to ensure adequate heart rate response and resolution of symptoms 1

Rationale for Management

• Beta-blockers and flecainide can both cause bradycardia, but the combination significantly increases this risk 1, 3

• Metoprolol reduction/discontinuation is preferred first as:

  • It directly slows AV nodal conduction and heart rate 1
  • The current dose is already low (6.25mg BID), suggesting it may be contributing to symptoms even at this dose 3
  • Flecainide is more critical for maintaining rhythm control post-ablation 4

• The current flecainide dose (150mg BID) is within the therapeutic range but may need adjustment if bradycardia persists 2

Follow-up Plan

• Reassess the patient within 1-2 weeks with ECG to evaluate heart rate and symptoms 1
• If symptoms persist despite medication adjustments, consider:
  • Further reduction of flecainide dose 2
  • Evaluation for possible sinus node dysfunction that may have been unmasked by the ablation procedure 1
  • Consideration of pacemaker if significant symptomatic bradycardia persists despite medication adjustments 1

Important Considerations

• Flecainide has a long half-life (12-27 hours), so changes in dose may take several days to reach steady state 2
• Proarrhythmic effects can occur with both medications, especially in the setting of electrolyte abnormalities 1
• Maintain potassium levels at ≥4.0 mEq/L to reduce risk of proarrhythmia 1
• Avoid abrupt discontinuation of beta-blockers; taper if discontinuation is necessary 1

Medication Adjustment Algorithm

1. First adjustment: Reduce metoprolol by 50% or discontinue completely based on severity of symptoms 1
2. If inadequate response after 1 week: Reduce flecainide to 100mg BID 2
3. If still inadequate after another week: Consider further reduction of flecainide to 50mg BID 2
4. If persistent symptomatic bradycardia despite medication adjustments: Evaluate for permanent pacemaker 1

This approach prioritizes symptom relief while maintaining rhythm control, which is essential in the post-ablation period to prevent AF recurrence 1, 4.