Myocarditis and Pericarditis as a Complication of Mpox: Case Series and Literature Review.

Monkeypox virus is a DNA virus in the orthopoxvirus family, and a multicountry 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 1 to 4 weeks post-infection. We present 2 clinical cases of mpox-related myocarditis from Canada. We identified 19 additional cases of myocarditis and/or pericarditis in the literature, and data were synthesized with our 2 cases. All 20 patients with available data were hospitalized, 6 of whom were admitted to an intensive care unit. Median time of cardiac symptom onset after initial mpox symptom onset was 5 (range, 0-14) days, elevated troponin was present in 19 of 19 cases (range, 165-21,200 ng/L), arrhythmias were described in 1 patient with Mobitz type 1 and 2 atrioventricular blocks, and echocardiograms showed reduced ejection fraction in 4 of 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 with placebo in shortening time to lesion resolution; however, in this article, we discuss nuances regarding antivirals in the setting of mpox-related myocarditis.