Is it safe to start Vyvanse (lisdexamfetamine) for Attention Deficit Hyperactivity Disorder (ADHD) in a patient with first-degree Atrioventricular (AV) block?

Safety of Lisdexamfetamine (Vyvanse) in a Patient with First-Degree AV Block

Lisdexamfetamine (Vyvanse) can be safely initiated in a 35-year-old male with first-degree AV block (PR interval 206 ms), provided there are no symptoms of hemodynamic compromise and regular cardiac monitoring is implemented.

Understanding First-Degree AV Block

First-degree AV block is defined as a prolongation of the PR interval beyond 0.20 seconds, where conduction is delayed but all impulses are conducted 1. In this patient's case:

• PR interval is 206 ms (just slightly prolonged)
• Heart rate is 66 bpm (normal)
• Sinus rhythm is present (normal)

Clinical Significance

First-degree AV block is generally benign when:

• PR interval is only mildly prolonged (<300 ms)
• Patient is asymptomatic
• No other conduction abnormalities exist

According to the ACC/AHA guidelines, permanent pacemaker implantation is not indicated for asymptomatic first-degree AV block 2. This indicates that mild, asymptomatic first-degree AV block is not considered a serious cardiac condition requiring intervention.

Considerations for Stimulant Therapy

Cardiac Effects of Lisdexamfetamine

Lisdexamfetamine, like other stimulants, can affect the cardiovascular system:

• May increase blood pressure (average increase <1 mmHg systolic) 3
• May increase heart rate (average increase 3.6 bpm) 3
• Listed adverse reactions include tachycardia (1%) and hypertension (1%) 4

Risk Assessment

Several factors suggest this patient can safely start lisdexamfetamine:

1. Mild conduction delay: PR interval of 206 ms is only slightly above normal
2. Normal heart rate: 66 bpm indicates good cardiac function
3. No symptoms: The case doesn't mention symptoms of hemodynamic compromise
4. Age: At 35 years, the patient is relatively young with likely fewer cardiovascular risk factors

Clinical Decision Making

The FDA label for lisdexamfetamine lists "risks to patients with serious cardiac disease" as a warning 4, but first-degree AV block alone, especially when mild and asymptomatic, does not constitute serious cardiac disease according to cardiac guidelines 2.

The ACC/AHA guidelines specifically state that:

• Permanent pacing is not indicated for asymptomatic first-degree AV block 2
• There is little evidence to suggest that pacemakers improve survival in patients with isolated first-degree AV block 2

This indicates that isolated first-degree AV block is not considered a significant cardiac risk factor.

Recommendations for Management

1. Baseline assessment:

   • Confirm absence of symptoms like dizziness, fatigue, or exercise intolerance
   • Check for other cardiovascular risk factors
   • Ensure no contraindicated medications (especially MAO inhibitors) 2

2. Initiation protocol:

   • Start at the lowest effective dose of lisdexamfetamine (30 mg daily)
   • Monitor vital signs at baseline and during dose titration
   • Obtain follow-up ECG after reaching stable dose

3. Ongoing monitoring:

   • Regular blood pressure and heart rate checks
   • Periodic ECG monitoring to assess PR interval
   • Watch for symptoms of worsening conduction (dizziness, syncope, fatigue)

4. Warning signs requiring reassessment:

   • Development of symptoms suggesting hemodynamic compromise
   • Significant increase in PR interval (>300 ms)
   • Development of higher-degree AV block
   • Significant increase in blood pressure or heart rate

Conclusion

Based on current guidelines, the mild first-degree AV block in this otherwise healthy 35-year-old male does not constitute a contraindication to lisdexamfetamine therapy. The ACC/AHA guidelines specifically note that asymptomatic first-degree AV block does not require intervention 2, and the FDA label does not list first-degree AV block as a specific contraindication 4.

With appropriate monitoring and follow-up, lisdexamfetamine can be safely initiated for the treatment of ADHD in this patient.