How to manage a 26-year-old female with cardiac dysrhythmia history, experiencing shortness of breath and palpitations, with ECG showing sinus bradycardia, on diltiazem (calcium channel blocker) 120mg daily?

Management of Sinus Bradycardia in a Young Female with Cardiac Dysrhythmia on Diltiazem

Diltiazem should be immediately discontinued in this 26-year-old female with shortness of breath, palpitations, and sinus bradycardia at 53 BPM, as it is the most likely cause of her symptoms and bradycardia. 1, 2

Assessment of Current Situation

• Current presentation: 26-year-old female with:

  • Shortness of breath and palpitations
  • ECG showing sinus bradycardia at 53 BPM
  • History of cardiac dysrhythmia
  • Currently on diltiazem 120mg daily

• Likely diagnosis: Medication-induced bradycardia

  • Diltiazem, a non-dihydropyridine calcium channel blocker, is known to cause bradycardia, conduction abnormalities, and hypotension 2
  • The American College of Cardiology recommends titrating down diltiazem in patients who develop bradycardia with heart rate <50 beats/minute 2

Immediate Management

1. Discontinue diltiazem

   • Diltiazem should be immediately discontinued as it is the most likely cause of the bradycardia and symptoms 1, 2
   • The patient's heart rate is approaching the threshold (50 BPM) where intervention is recommended

2. Monitor vital signs and symptoms

   • Continuous cardiac monitoring to assess for worsening bradycardia or conduction abnormalities
   • Monitor blood pressure for hypotension
   • Assess for signs of hemodynamic compromise

3. If severe symptomatic bradycardia develops:

   • Administer atropine (0.6 to 1.0 mg) if bradycardia worsens 3
   • If no response to atropine, consider isoproterenol cautiously 3

Alternative Treatment Options

For management of the underlying cardiac dysrhythmia (assuming it was supraventricular tachycardia):

1. First-line alternatives:

   • Beta-blockers (if no contraindications) 1
   • For AVNRT (common in young females), consider:
     • Oral verapamil (without concomitant beta-blocker) 1
     • Flecainide, propafenone, or sotalol (if no structural heart disease) 1

2. Avoid combination therapy:

   • The combination of beta-blockers with non-dihydropyridine calcium channel blockers (like diltiazem) significantly increases the risk of bradycardia and heart block 4
   • If combination therapy is absolutely necessary, careful monitoring of heart rate, blood pressure, and ECG is essential 1, 4

Long-term Management Considerations

1. Electrophysiology study and catheter ablation:

   • Should be considered as definitive treatment if the patient has recurrent SVT 1
   • Success rates for ablation of AVNRT exceed 95% with low complication rates 1

2. If medical therapy is preferred:

   • Beta-blockers alone may be sufficient for rate control
   • If calcium channel blockers are needed, lower doses should be used with careful monitoring 5
   • Consider single-dose "pill-in-pocket" approach for infrequent episodes 1

Important Precautions

• Avoid restarting diltiazem without careful consideration of alternatives, as recurrence of bradycardia is likely
• Monitor for withdrawal symptoms after discontinuation of diltiazem
• Evaluate for underlying sinus node dysfunction that may have been unmasked by diltiazem
• Consider temporary cardiac monitoring until heart rate normalizes and symptoms resolve

This young patient's presentation strongly suggests diltiazem-induced bradycardia, which requires immediate discontinuation of the medication and consideration of alternative treatments for her underlying cardiac dysrhythmia.