Monkeypox may potentially cause heart damage in some patients, according to a new case study published Friday in JACC: Case Reports.
A 31-year-old male tested positive for monkeypox and developed acute myocarditis — inflammation of the heart muscle — one week after developing monkeypox symptoms.
Scientists say the case report suggests that heart inflammation may be a rare complication associated with monkeypox.
According to Dr. Jorge Salinas, an infectious diseases specialist and a hospital epidemiologist at Stanford University, other viruses, including enteroviruses and the smallpox virus, which is related to the monkeypox virus, are known to impact the heart.
Other patients diagnosed with monkeypox in the 2022 outbreak have developed myocarditis, however, infectious disease experts say it is likely a rare complication.
“As the outbreak continues, we will hear of a few more cases but I don’t expect the number to be large,” Salinas told Healthline.
The patient, a healthy 31-year-old male, visited a health clinic five days after the onset of monkeypox symptoms. He had been experiencing malaise, myalgia, fever, and multiple skin lesions.
He tested positive for monkeypox and returned to the emergency room three days later because he was experiencing chest pain and tightness across his left arm.
The patient underwent multiple heart tests, which demonstrated that he had experienced a cardiac stress injury. A cardiac magnetic resonance test, which takes images of the heart, found that the patient had myocardial inflammation.
The patient fully recovered within one week.
According to the researchers, the case suggests that myocarditis may be a complication of monkeypox, however, more research is needed to further understand the link between monkeypox and heart injury.
“Clinicians should be vigilant in a patient with monkeypox describing chest pain to look for this rare clinical manifestation, which completely resolved in this patient,” Dr. Monica Gandhi, an infectious disease specialist with University of California, San Francisco, said.
Monkeypox typically causes self-limited symptoms, including skin lesions, myalgia, and fever, that clears up within a few weeks.
Gandhi says that the recent monkeypox outbreak — at nearly 52,000 cases in 110 countries — is the largest monkeypox outbreak that the world has experienced since the infection was first described in 1958.
“Therefore, this outbreak provides the opportunity to define the clinical characteristics of this infection in more detail,” Gandhi said.
Myocarditis is a complication associated with numerous infectious diseases. Past
“Myocarditis can be caused by a variety of viruses ranging from influenza to coxsackie viruses, to influenza virus, to smallpox and to SARS-CoV2,” Dr. Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security and an infectious disease expert, told Healthline.
Evidence has previously associated myocarditis with smallpox, which is more dangerous compared to monkeypox. Because monkeypox is related to smallpox, scientists believe that monkeypox may similarly damage the heart in rare circumstances.
“Smallpox is a related virus to monkeypox and was associated with myocarditis (inflammation of the heart), as was the smallpox vaccine,” Gandhi said.
Patients with viral myocarditis typically first experience fever, malaise, and myalgias before suddenly developing cardiac symptoms.
The inflammation is likely caused by the virus itself along with inflammation resulting from the body’s immune response.
“In some instances, it’s direct viral invasion of cardiac myocytes with resulting dysfunction. In other cases, it can be an immune response to the pathogen causing heart damage,” Adalja said, adding that it can also be a combination of the two.
Adalja does not expect myocarditis to be a common issue in people diagnosed with monkeypox.
“Myocarditis does not seem to be a frequent complication of monkeypox — hence only one case report,” Adalja said.
A new case study detailing a healthy male in his 30s who was diagnosed with monkeypox and later developed myocarditis suggests that the infection may potentially cause heart damage in some patients. Infectious diseases experts say that heart inflammation has been linked to other infectious diseases, however, they expect it to be a rare complication of monkeypox.