What are the considerations for using Vyvanse (lisdexamfetamine) in patients with a right bundle branch block (RBBB)?

Using Vyvanse (Lisdexamfetamine) in Patients with Right Bundle Branch Block (RBBB)

Vyvanse (lisdexamfetamine) should be used with caution in patients with right bundle branch block (RBBB) due to its cardiovascular effects, and requires pretreatment cardiac screening and ongoing monitoring. 1

Cardiovascular Considerations with Vyvanse

• Prior to initiating Vyvanse in patients with RBBB, a thorough assessment for the presence of cardiac disease (including careful history, family history of sudden death or ventricular arrhythmia, and physical examination) is mandatory 1
• Vyvanse is a central nervous system stimulant that can increase heart rate and blood pressure, which may potentially exacerbate conduction abnormalities in patients with pre-existing RBBB 1, 2
• The FDA label specifically requires assessment for cardiac disease before prescribing lisdexamfetamine, as CNS stimulants can increase cardiac workload 1

Understanding RBBB and Its Implications

• RBBB is characterized by QRS duration ≥120 ms in adults, an rSR' pattern in leads V1-V2, and S waves of greater duration than R waves in leads I and V6 3
• RBBB is detected in approximately 1-2.5% of the general population and may be an isolated finding or associated with underlying cardiovascular disorders 3, 4
• While isolated RBBB is often benign, it can be a marker for underlying cardiac disease in some patients, which may increase risk when using stimulant medications 3, 5

Risk Assessment Before Prescribing Vyvanse

• Evaluate for symptoms such as syncope, presyncope, dizziness, fatigue, or exercise intolerance, which may indicate more significant conduction system disease 4
• Consider cardiac imaging (echocardiography) to evaluate for right ventricular enlargement or dysfunction, structural heart disease, and left ventricular hypertrophy in patients with RBBB 4
• Assess for progression to more advanced conduction abnormalities, as bifascicular block (RBBB plus left anterior or posterior fascicular block) carries higher risk 6
• Be particularly cautious if the patient has alternating bundle branch block, which is a Class I indication for permanent pacemaker implantation 6

Monitoring Recommendations

• Regular ECG monitoring is recommended to assess for any changes in conduction patterns or QRS duration while on Vyvanse 4, 1
• Monitor blood pressure and heart rate at baseline and periodically during treatment, as Vyvanse can increase both parameters 1
• Watch for symptoms of worsening cardiac conduction, including dizziness, syncope, or palpitations 4
• Be vigilant for signs of progression from isolated RBBB to more complex conduction disorders, which would warrant discontinuation of Vyvanse 6, 4

Special Considerations

• Patients with RBBB plus left anterior or posterior fascicular block (bifascicular block) are at higher risk for progression to complete heart block and should be monitored more closely if prescribed Vyvanse 6
• If syncope occurs in a patient with RBBB taking Vyvanse, consider immediate discontinuation and cardiac evaluation, as this may indicate progression to higher-degree AV block 6
• Masquerading bundle branch block (RBBB pattern in precordial leads with LBBB pattern in limb leads) is a rare but poor prognostic sign and would be a contraindication to Vyvanse therapy 7

Dosing Considerations

• Consider starting at a lower dose (e.g., 20 mg daily) in patients with RBBB and titrate more cautiously than in patients without conduction abnormalities 1
• The maximum recommended dosage of Vyvanse is 70 mg once daily, but lower maximum doses may be appropriate for patients with cardiac conduction disorders 1
• Administer Vyvanse in the morning to minimize potential sleep disturbances, which could further stress the cardiovascular system 1

Alternative Considerations

• For patients with more severe forms of conduction disease (e.g., bifascicular block with syncope), consider non-stimulant medications for ADHD treatment 6
• If Vyvanse is deemed necessary despite significant conduction concerns, consultation with a cardiologist is strongly recommended before initiation 4