Transient, high-grade atrioventricular block from high-dose cyclophosphamide

Area of Science:

• Cardiology
• Oncology
• Pharmacology

Background:

• Cyclophosphamide is a key alkylating agent in stem cell transplantation, valued for its anticancer and myeloablative effects.
• Known cardiac complications include heart failure, pericarditis, and arrhythmias, but high-grade atrioventricular block is seldom reported.

Observation:

• A 71-year-old male patient developed high-grade atrioventricular block hours post-high-dose cyclophosphamide administration.
• The patient's condition resolved after temporary pacemaker insertion and cyclophosphamide discontinuation.

Findings:

• High-dose cyclophosphamide can precipitate high-grade atrioventricular block, a rare but serious cardiac adverse event.
• This cardiac complication appears reversible upon cessation of the drug and supportive care.

Implications:

• Pre-treatment cardiac screening for conduction abnormalities is crucial for patients receiving high-dose cyclophosphamide.
• Clinicians should consider cyclophosphamide as a potential cause of new-onset atrioventricular block in transplant recipients.
• Alternative chemotherapeutic agents may be considered for patients with pre-existing cardiac conduction issues.