Acute Myocarditis as an Immune-Mediated Complication of Mpox Infection

Cardiac involvement is an uncommon and incompletely characterized complication of mpox infection.

A 32-year-old man with well-controlled HIV and polymerase chain reaction-confirmed mpox developed acute chest pain days after a vesiculopustular rash. High-sensitivity troponin I peaked at 12,717 ng/L with elevated inflammatory markers. Coronary and embolic causes were excluded. Cardiac magnetic resonance (CMR) demonstrated lateral-wall edema on T2-weighted imaging and nonischemic late gadolinium enhancement with preserved ejection fraction, satisfying the updated Lake Louise Criteria. He recovered fully with supportive care.

Mpox-associated myocarditis has predominantly been reported in young, largely immunocompetent men, including some with well-controlled HIV. The mechanism remains uncertain; immune-mediated injury and direct viral involvement both remain possible. This case underscores multiparametric CMR as a noninvasive diagnostic tool that may obviate endomyocardial biopsy in hemodynamically stable patients.

Mpox can cause acute myocarditis in immunocompetent patients. Multiparametric CMR enables noninvasive confirmation and may spare selected patients from endomyocardial biopsy.