Elevated defibrillation threshold with venlafaxine therapy

Area of Science:

• Cardiology
• Pharmacology
• Psychiatry

Background:

• Depression is a frequent comorbidity in patients with heart failure and implantable cardioverter-defibrillators (ICDs).
• Managing comorbidities alongside device therapy requires careful consideration of potential drug-device interactions.

Observation:

• A patient with nonischemic cardiomyopathy, cardiac arrest history, and depression received an ICD.
• During initial device testing, the ICD failed to achieve internal defibrillation.

Findings:

• Venlafaxine, an antidepressant with known cardiac sodium channel blocking properties, was identified as a potential cause for the elevated defibrillation threshold.
• Discontinuation of venlafaxine resulted in successful internal defibrillation by the ICD.

Implications:

• Clinicians should consider venlafaxine's potential adverse drug-device interactions in patients with ICDs.
• Further research is necessary to elucidate the clinical significance of venlafaxine use in the ICD population.