Monkeypox induced acute myocarditis in a young healthy adult

Introduction

Monkeypox is a zoonotic double-stranded DNA virus of the genus Orthopoxvirus.¹ It was first isolated from monkeys in 1958, and the first human case was reported in Congo in 1970.¹ Monkeypox is endemic in Central and Western Africa, where thousands of cases are reported annually. Since May 2022, outbreaks of human cases with monkeypox have occurred globally, particularly in men who have sex with men.²

Most monkeypox cases are mild and self-limited.² Complications such as encephalitis, keratitis, and pneumonia may potentially occur in immunocompromised patients, children <8 years, and pregnant women.² Acute myocarditis is very rare in monkeypox. There are only 8 case reports of monkeypox patients complicated with myocarditis. To our knowledge, we present the ninth reported case of myocarditis associated with monkeypox infection.

Case report

A 21-year-old man without a history of systemic illness presented to the emergency room with retrosternal oppressive chest pain without radiation that started 4 days prior and vesiculopustules for the last 9 days. He also had associated fever, myalgia, nausea, vomiting, headache, and watery diarrhea. The patient denied any personal or family history of cardiovascular disease, new medications, recent travels, or ill contacts. Upon further history taking, he did report multiple same-sex partners. The physical examination demonstrated scattered perifollicular pustules on an erythematous base involving the face, trunk, suprapubic area, and extremities (Fig 1). Cervical lymph nodes were palpable bilaterally. Laboratory tests, including complete blood count, comprehensive metabolic panel, electrocardiogram, and echocardiogram were within normal limits. HIV, hepatitis profile, and influenza A and influenza B were negative. However, troponin I levels were elevated at 21.20 ng/mL (normal range: 0-0.04 ng/mL), and cardiac magnetic resonance imaging demonstrated subepicardial late enhancement at the base and inferolateral segments consistent with acute myocarditis. The internal medicine and cardiology team started the patient on cardiac monitoring and high-dose aspirin for his myocarditis. Our dermatology service was consulted for his vesiculopustular eruption. Given the above clinical history and examination, we suspected the possibility of a monkeypox infection. A qualitative, real-time polymerase chain reaction test detected the monkeypox virus, confirming that this patient had a monkeypox infection complicated by acute myocarditis. The patient was hemodynamically stable throughout his 5-day hospital stay. His chest pain resolved in 2 days and his troponins decreased to normal levels. He was discharged home on colchicine 0.6 mg by mouth daily for his myocarditis, as per his cardiologist. The patient remained in isolation at home for at least 21 days until his cutaneous lesions resolved. Eight weeks later, his follow-up with the cardiologist and new cardiac magnetic resonance imaging were unremarkable, with no sequelae of myocarditis.

Fig 1.

Monkeypox virus lesions. Scattered perifollicular pustules on an erythematous base on the trunk, suprapubic area, and lower extremities.

Discussion

Myocarditis is an inflammatory disease of the myocardium, which can be related to many underlying conditions. Viral myocarditis can be caused by 2 potential mechanisms: direct injury inflicted by the virus due to tropism for the myocardium or injury mediated by the immune system as a result of Th1 (T helper type 1) response that may elicit cardiac inflammation.³ Viral myocarditis can be mild and self-limited or result in fulminant myocarditis. Some cases may evolve into a noninfectious chronic phase with myocardial fibrosis, dilated cardiomyopathy, or heart failure.⁴

Diagnosing myocarditis may be difficult as a result of its variable presentation.⁵ Viral myocarditis is frequently presumed when cardiac symptoms like dyspnea and/or chest pain ensue systemic symptoms of viral infection.⁵ A diagnosis of suspected myocarditis may be made by the clinical presentation in combination with noninvasive diagnostic findings.⁵ The diagnosis of myocarditis is usually presumptive, taking into consideration the time of exposure to the virus.⁵ Acute myocarditis prognosis depends on the stage of the disease at which the patient presents; it may either resolve in a few weeks or progresses to cardiac complications.⁵

There are only 8 previous patients reported in the English written medical literature describing acute myocarditis that occurred a few days after cutaneous lesions of monkeypox.4, 5, 6, 7 Our patient and those 8 reported patients suggest that the monkeypox virus may have tropism for the myocardium or cause injury mediated by the immune response. All the patients with monkeypox-induced myocarditis reported so far have been hemodynamically stable, with their symptoms normalizing within 1 week and the myocarditis resolving without sequelae. Only 2 patients received oral tecovirimat.4, 7 The remaining 6 patients received no monkeypox treatment because of the limited availability of tecovirimat and brincidofovir.

In conclusion, our case emphasizes the potential complication of myocarditis in monkeypox virus-infected patients. There should be awareness among physicians and dermatologists to monitor patients for plausible complications that may require monkeypox-directed treatment. Currently with tecovirimat more widely available, CDC (Centers for Disease Control) recommends considering monkeypox treatment in patients with myocarditis.^8,9

Conflicts of interest

None disclosed.