Is it appropriate to start Vyvanse (lisdexamfetamine) for ADHD in a patient with a first-degree atrioventricular (AV) block?

Vyvanse in First-Degree AV Block: Contraindicated for ADHD Treatment

Vyvanse (lisdexamfetamine) is contraindicated for a 20-year-old female with first-degree AV block due to the risk of worsening cardiac conduction abnormalities.

Rationale for Contraindication

First-degree AV block represents a delay in conduction at the AV node level, with PR interval prolongation beyond 0.20 seconds. While often considered benign, it requires careful consideration when prescribing medications that may affect cardiac conduction.

Cardiac Effects of Stimulants

• Lisdexamfetamine (Vyvanse) is a prodrug that converts to d-amphetamine, a central nervous system stimulant 1
• Stimulants like Vyvanse increase catecholamine levels (dopamine and norepinephrine) which can:
  • Increase heart rate
  • Increase blood pressure
  • Potentially worsen existing conduction abnormalities

Guideline-Based Contraindications

The ACC/AHA/HRS guidelines specifically list precautions regarding medications in patients with AV block:

• Beta blockers and nondihydropyridine calcium channel antagonists are contraindicated in "AV block greater than first degree" 2
• While first-degree AV block isn't an absolute contraindication, stimulants could potentially worsen conduction and progress the block to a higher degree

Risk Assessment

Potential Complications

• Progression to higher-degree AV block: Stimulants may exacerbate conduction delays
• Case reports have documented AV nodal re-entrant tachycardia associated with stimulant treatment in adolescents 3
• First-degree AV block can be a marker for underlying cardiac disease that could be exacerbated by stimulants

Monitoring Considerations

The European Society of Cardiology recommends:

• Close monitoring for patients with first-degree AV block 2
• Periodic ECG follow-up, with more frequent monitoring if symptoms develop 4
• Assessment for risk factors suggesting potential progression, including markedly prolonged PR interval (>300 ms) 4

Alternative Approaches

For a 20-year-old female with ADHD and first-degree AV block:

1. Non-stimulant ADHD medications should be considered first-line:

   • Atomoxetine
   • Guanfacine
   • Bupropion (with caution and cardiac monitoring)

2. Cardiac evaluation before any stimulant consideration:

   • Comprehensive cardiac assessment including echocardiography
   • Evaluation by a cardiologist to determine the etiology and significance of the AV block
   • Assessment of PR interval duration (particularly if >300 ms, which increases risk)

3. If stimulants are absolutely necessary (after non-stimulants fail):

   • Cardiology consultation is mandatory
   • Regular ECG monitoring during titration and maintenance
   • Lower starting doses with gradual titration
   • Regular monitoring of vital signs

Conclusion

The presence of first-degree AV block in a young patient is concerning and warrants caution when considering stimulant medications like Vyvanse. While limited data exists specifically on Vyvanse in patients with first-degree AV block, the potential cardiac risks outweigh the benefits when safer alternatives are available. The priority should be to treat ADHD while ensuring cardiovascular safety through non-stimulant options and appropriate cardiac monitoring.