How to manage a 61-year-old female with hypothyroidism, history of new onset atrial fibrillation (A-fib) with rapid ventricular response (RVR), and symptomatic tachycardia, who is scheduled for a total thyroidectomy?

Management of Atrial Fibrillation in a 61-Year-Old Female with Hypothyroidism Scheduled for Thyroidectomy

For a 61-year-old female with hypothyroidism, new onset atrial fibrillation with RVR, and symptomatic tachycardia who is scheduled for thyroidectomy, metoprolol should be continued for rate control until after the thyroidectomy, with close perioperative monitoring for potential cardiovascular complications.

Pre-Thyroidectomy Management

Rate Control Strategy

• Metoprolol succinate 25 mg daily is appropriate for this patient's symptomatic tachycardia, as beta-blockers are first-line agents for rate control in patients with thyroid disease and atrial fibrillation 1
• The patient's 7-day event monitor showed no recurrent A-fib but did show symptomatic tachycardia, justifying the use of metoprolol for symptom control 1, 2
• Non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) would be an appropriate alternative if beta-blockers were contraindicated 1

Anticoagulation Considerations

• With a CHA2DS2-VASc score of 1 (for female sex), the decision to not start anticoagulation is appropriate as current guidelines do not strongly recommend anticoagulation for this low-risk profile 1
• The patient has had no recurrent A-fib on monitoring, further supporting the decision to withhold anticoagulation 1

Perioperative Management

Thyroidectomy Considerations

• Patients with hypothyroidism undergoing surgery have increased risk of:
  • Intraoperative hypotension (61% vs 30% in euthyroid patients) 3
  • Postoperative gastrointestinal complications (19% vs 1%) 3
  • Neuropsychiatric complications (38% vs 18%) 3
• Continue levothyroxine therapy through the perioperative period to maintain normal TSH levels 1
• Beta-blocker therapy should be continued perioperatively to control potential tachyarrhythmias 2

Specific Perioperative Precautions

• Monitor closely for hemodynamic instability during surgery, as hypothyroid patients are more prone to intraoperative hypotension 3
• Be vigilant for atypical presentation of infections, as hypothyroid patients less frequently manifest fever despite comparable infection rates (35% vs 79%) 3
• Consider the potential for delayed anesthetic recovery, though this is not significantly different from euthyroid patients 3

Post-Thyroidectomy Management

Thyroid Hormone Replacement

• Postoperative levothyroxine is indicated for all patients after total thyroidectomy 1
• TSH should be kept in the normal range through appropriate levothyroxine dosing, as TSH suppression is not necessary 1
• Maintain euthyroid state to reduce risk of recurrent atrial fibrillation, as restoration of normal thyroid function is associated with spontaneous reversion to sinus rhythm 1, 4

Cardiovascular Monitoring

• Continue monitoring for recurrent atrial fibrillation or tachycardia after surgery 2
• Adjust beta-blocker dosing based on heart rate response and symptoms 5
• Once euthyroid state is restored, recommendations for antithrombotic prophylaxis are the same as for patients without thyroid disease 1

Important Caveats

• Phentermine was likely the trigger for the patient's A-fib and tachycardia and should be permanently discontinued 2
• Combined cardiac and thyroid surgery has been reported to be safe with appropriate perioperative management 6, 7
• Hypothyroidism is typically associated with bradycardia rather than tachycardia, so ongoing monitoring for other potential causes of tachycardia is warranted 8, 4
• If recurrent symptomatic A-fib occurs post-thyroidectomy despite rate control, consider a rhythm control strategy 5