What is the recommended treatment plan for a 61-year-old female after her first episode of Supraventricular Tachycardia (SVT) that required adenosine?

Treatment Plan After First Episode of SVT Requiring Adenosine in a 61-Year-Old Female

For a 61-year-old female after her first episode of SVT requiring adenosine, catheter ablation should be considered as the definitive treatment due to its high success rate of approximately 95% for AVNRT with low complication rates, providing potential for cure without chronic medication. 1

Immediate Post-Episode Management

• Monitor for recurrence of SVT, vital sign stability, and resolution of symptoms after adenosine administration 1
• Obtain a 12-lead ECG to document return to normal sinus rhythm
• Consider basic laboratory tests to rule out electrolyte abnormalities or other triggers

Diagnostic Evaluation

• Echocardiogram to assess for structural heart disease
• Holter monitor or event recorder if symptoms suggest intermittent arrhythmias
• Electrophysiological study (EPS) to determine the specific type of SVT (likely AVNRT based on response to adenosine) 1

Treatment Options

1. Definitive Treatment: Catheter Ablation

• Recommended as first-line therapy for recurrent SVT 1
• Benefits:
  • High success rate (~95% for AVNRT)
  • Low complication rate
  • Potential for definitive cure
  • Eliminates need for chronic medication therapy

2. Pharmacological Management (if ablation is declined or contraindicated)

• First-line medications:

  • Oral beta-blockers (e.g., metoprolol, atenolol)
  • Calcium channel blockers (e.g., diltiazem, verapamil) 2, 1

• Second-line medications:

  • Flecainide may be considered for patients without structural heart disease 1, 3
    • Starting dose: 50 mg every 12 hours
    • May increase in increments of 50 mg twice daily every four days until efficacy achieved
    • Maximum recommended dose: 300 mg/day 3

Important: Calcium channel blockers should be avoided in patients with suspected systolic heart failure 2

Patient Education for Future Episodes

1. Teach vagal maneuvers:

   • Valsalva maneuver: bearing down against closed glottis for 10-30 seconds
   • Application of ice-cold wet towel to face 2

2. When to seek medical attention:

   • If SVT persists despite vagal maneuvers
   • If associated with chest pain, shortness of breath, or syncope
   • If episodes become more frequent or prolonged

Follow-up Recommendations

• Cardiology follow-up within 1-2 weeks
• If on medication therapy, monitor for side effects and efficacy
• If ablation is performed, follow-up ECG and assessment at 1 month

Special Considerations

• If the patient has impaired venous return or right heart dysfunction, higher doses of adenosine may be required for future episodes 4
• Older patients with a history of SVT have been shown to have better response rates to adenosine 5
• Recurrence after adenosine is common (reported in up to 57% of cases), so definitive treatment should be strongly considered 6

Pitfalls to Avoid

• Mistaking other arrhythmias for SVT (adenosine can help differentiate but may not always be diagnostic) 6
• Delaying definitive treatment in patients with recurrent episodes
• Using calcium channel blockers in patients with heart failure or hypotension 2, 1
• Assuming a single episode means low recurrence risk

The American College of Cardiology/American Heart Association guidelines strongly support catheter ablation as the definitive treatment for SVT, particularly for patients who have had symptomatic episodes requiring medical intervention 2, 1.