What are the management options for a patient with Supraventricular Tachycardia (SVT) on Flecainide with a heart rate of 59 beats per minute, indicating bradycardia?

Management of SVT in a Patient on Flecainide with Bradycardia

For a patient with SVT on flecainide who has developed bradycardia (HR 59), the flecainide dose should be reduced or discontinued and alternative treatment options should be considered, including catheter ablation as definitive therapy.

Assessment of Flecainide-Induced Bradycardia

• Flecainide is a Class IC antiarrhythmic agent that can cause significant bradycardia as a side effect, especially at higher doses 1
• A heart rate of 59 bpm indicates bradycardia, which is likely due to the sodium channel blocking properties of flecainide 2
• Flecainide can cause conduction abnormalities including sinus node dysfunction and AV block, particularly in patients with pre-existing conduction disease 3, 2

Immediate Management Steps

• Reduce the dose of flecainide as the first intervention to address the bradycardia 1, 3
• Monitor the patient's ECG for QRS widening, QT prolongation, or other conduction abnormalities that may accompany bradycardia 2
• If symptoms of hemodynamic compromise are present (dizziness, syncope, fatigue), consider temporary discontinuation of flecainide 4, 2

Alternative Treatment Options

• Electrophysiological (EP) study with catheter ablation is the definitive treatment for SVT and should be strongly considered, especially given the medication side effect 1
• Oral beta blockers, diltiazem, or verapamil can be considered as alternative pharmacological options if the patient is not a candidate for ablation 1, 5
• For patients with infrequent episodes, a "pill-in-the-pocket" approach with beta blockers, diltiazem, or verapamil may be reasonable 1

Long-term Management Considerations

• If pharmacological therapy is preferred over ablation, consider these options:

  • Beta blockers are first-line agents with fewer conduction effects than flecainide 1, 5
  • Calcium channel blockers (diltiazem or verapamil) are effective alternatives with Class I recommendation 1
  • Propafenone (another Class IC agent) may be considered but carries similar risks of bradycardia 1

• For patients who cannot tolerate any of these medications, sotalol or dofetilide may be reasonable alternatives, though they require careful monitoring 1

Monitoring and Follow-up

• Regular ECG monitoring is essential for any patient on antiarrhythmic therapy, especially after dose adjustments 2
• Teach patients to perform vagal maneuvers as a non-pharmacological method to terminate acute SVT episodes 1
• Monitor for symptoms of bradycardia including fatigue, dizziness, syncope, or exercise intolerance 2

Special Considerations and Pitfalls

• Flecainide has a narrow therapeutic window and can cause proarrhythmic effects, especially in patients with structural heart disease 4, 2
• Avoid combining flecainide with other drugs that affect cardiac conduction (beta blockers, calcium channel blockers) without careful monitoring, as this can worsen bradycardia 4, 2
• Flecainide-induced QT prolongation can lead to life-threatening arrhythmias in rare cases, necessitating prompt discontinuation if observed 2
• Patients with bradycardia on flecainide should avoid situations that further lower heart rate (e.g., extreme vagal maneuvers) until the medication is adjusted 1, 5