What is the management plan for a 71-year-old female with hypothyroidism, rotator cuff tear, and supraventricular tachycardia (SVT) who presents with palpitations and has a history of similar episodes?

Management of Supraventricular Tachycardia in a 71-Year-Old Female with Hypothyroidism

Catheter ablation is the recommended first-line treatment for this patient with recurrent symptomatic SVT, as it offers the highest success rate and can eliminate the need for long-term medication. 1

Diagnosis and Immediate Management

The patient presented with a clear case of supraventricular tachycardia (SVT) with the following features:

• Heart rate of 186 bpm
• Regular rhythm
• Successful termination with IV adenosine
• History of recurrent episodes (previously lasting 5-15 minutes)
• Previously self-terminated with coughing maneuvers (vagal maneuvers)

The elevated troponin levels (11.19 → 68.9 → 101.12) likely represent demand ischemia due to prolonged tachycardia rather than primary coronary disease, as noted by the cardiology consultation.

Long-Term Management Options

First-Line Recommendation: Catheter Ablation

Catheter ablation is strongly recommended as the first-line approach for this patient based on:

• Recurrent symptomatic episodes
• Failure of vagal maneuvers during the current episode
• Age and comorbidities that make long-term medication less desirable
• High success rate (>90%) with low complication risk

The 2015 ACC/AHA/HRS guidelines clearly state that catheter ablation is recommended as first-line therapy for patients with recurrent symptomatic SVT 1.

Alternative Pharmacological Options

If the patient declines ablation or has contraindications, medication options include:

1. Beta-blockers (first choice):

   • Effective for preventing recurrent SVT
   • Caution needed due to patient's age (71) and hypothyroidism
   • Monitor for bradycardia, especially with levothyroxine therapy 2

2. Calcium channel blockers (alternative first choice):

   • Diltiazem or verapamil
   • Similar efficacy to beta-blockers
   • May be better tolerated in some patients

3. Other antiarrhythmic options (second-line):

   • Flecainide or propafenone (if no structural heart disease)
   • Sotalol (if structural heart disease present)
   • Amiodarone (reserved for cases resistant to other therapies)

Thyroid Considerations

The patient's hypothyroidism requires careful consideration:

• Ensure adequate levothyroxine dosing (currently 75 mcg)
• Thyroid dysfunction can contribute to arrhythmias 3
• Hypothyroidism is more commonly associated with ventricular arrhythmias, but can rarely cause SVT 4
• Monitor thyroid function tests to ensure euthyroid state

Follow-Up Plan

1. Immediate referral to electrophysiologist for evaluation and discussion of catheter ablation
2. Echocardiogram (as planned by cardiology) to assess for structural heart disease
3. Thyroid function testing to ensure optimal levothyroxine dosing
4. If ablation is delayed or declined:
   • Initiate beta-blocker or calcium channel blocker therapy
   • Teach proper vagal maneuver techniques
   • Provide event monitor for documentation of future episodes

Patient Education

Instruct the patient on:

• Recognition of SVT symptoms
• Proper vagal maneuver techniques (modified Valsalva maneuver is most effective)
• When to seek emergency care (prolonged episodes, hemodynamic instability)
• Importance of medication compliance if prescribed

Pitfalls and Caveats

1. Avoid digoxin in patients with SVT and pre-excitation (if present), as it can enhance conduction through accessory pathways
2. Monitor for drug interactions between antiarrhythmics and levothyroxine
3. Beware of overtreatment with levothyroxine, which can precipitate arrhythmias, especially in elderly patients 2
4. Don't attribute all palpitations to SVT - ensure ongoing monitoring for other arrhythmias
5. Don't delay ablation referral - recurrent SVT episodes can lead to tachycardia-induced cardiomyopathy if frequent and prolonged

By following this management approach, the patient has an excellent prognosis for resolution of her SVT symptoms and prevention of future episodes.