Durvalumab-Associated Myocarditis Initially Presenting With Sinus Bradycardia Progressing Into Complete Heart Block

Area of Science:

• Cardiology
• Oncology
• Immunology

Background:

• Durvalumab, a programmed cell death ligand-1 (PD-L1) inhibitor, is approved for advanced urothelial and non-small cell lung cancer (NSCLC).
• Immune checkpoint inhibitors (ICIs) offer improved side effect profiles over traditional chemotherapy.
• Myocarditis is a recognized, albeit rare, side effect of ICI therapy.

Observation:

• A 71-year-old male with NSCLC on durvalumab developed sinus bradycardia and elevated troponin levels.
• The patient experienced complete heart block (CHB) and polymorphic ventricular tachycardia.
• Cardiac magnetic resonance imaging was not feasible due to hemodynamic instability.

Findings:

• Durvalumab-induced myocarditis was diagnosed based on clinical presentation and elevated cardiac biomarkers, excluding coronary artery disease.
• Initial treatment with methylprednisolone improved troponin levels but not conduction abnormalities.
• The patient required transvenous pacing, followed by permanent pacemaker implantation due to persistent CHB and ventricular arrhythmias.

Implications:

• This case underscores the potential for severe cardiac adverse events, including myocarditis and heart block, with durvalumab therapy.
• Prompt recognition and management, including immunosuppression and pacing, are crucial for patients with ICI-induced cardiotoxicity.
• Continued monitoring and investigation into the mechanisms and optimal treatment of ICI-related myocarditis are warranted.