Myocarditis and pericarditis as a complication of mpox: case series and literature review

Monkeypox virus (MPXV) is a DNA virus in the orthopoxvirus family and a multi-country outbreak was declared a Public Health Emergency of International Concern both in 2022 and 2024. Myocarditis is a known complication of many viral infections, and chest pain and electrocardiogram changes may occur from one to four weeks post-infection. We present two clinical cases of mpox-related myocarditis from Canada. We identified nineteen additional cases of myocarditis and/or pericarditis in the literature and data were synthesized with our two cases. All twenty patients with available data were hospitalized, six of whom were admitted to an intensive care unit. Median time of cardiac symptom onset after initial mpox symptom onset was five (range 0 to 14) days, elevated troponin was present in 19/19 cases (range 165 to 21,2000 ng/L), arrhythmias were described in one patient with Mobitz type 1 and 2 atrioventricular blocks, and echocardiograwms showed reduced ejection fraction in 4/15 patients. There were no deaths reported. Management of mpox involves symptom control and anti-inflammatories. Recent trials have not shown benefit of tecovirimat compared to placebo in shortening time to lesion resolution, however in this manuscript we discuss nuances regarding antivirals in the setting of mpox-related myocarditis.