Viral infections are a common cause of myocarditis, an inflammation of the heart muscle called the myocardium. Recent research indicates an association between Covid-19 and the heart condition that can lead to hospitalization, heart failure and sudden death.
According to a study conducted by researchers at the US Centers for Disease Control and Prevention (CDC), patients with the disease had nearly 16 times the risk of myocarditis compared to people who were not infected with the new coronavirus. The analysis considered the period from January 2019 to May 2021.
To arrive at the result, the researchers used resources from a large database of more than 900 hospitals and health services in the United States. Health information from more than 36 million people was analyzed, of which 1,452,773 (4%) confirmed a diagnosis of Covid-19 between March 2020 and January 2021, and 5,069 (0.01%) received a diagnosis of myocarditis between March 2020 and February this year.
Patients with myocarditis were slightly older than those without the condition. Myocardial inflammation was also more common in men (59.3% of cases) than in women.
Inpatient myocarditis cases were 42.3% higher in 2020 compared to the previous year. In the period from March 2020 to January 2021, which coincides with the Covid-19 pandemic, the risk of myocarditis was 0.146% among patients diagnosed with the new coronavirus, considering hospitalized patients and individuals who underwent outpatient care. Among people who were not infected, the rate dropped to 0.009%.
According to the study, the analysis of patients with Covid-19 in the period showed that they had 15.7 times the risk of myocarditis compared to those who were not infected. Risk rates varied according to age, showing a greater risk for the extremes of age. The rates ranged from 7 times for patients aged 16 to 39 years to more than 30 times higher for those under 16 years or older than 75 years.
Need for further studies
The authors emphasize that the exact mechanism of the new coronavirus infection that may be related to myocarditis remains unknown. However, they emphasize that the association between the two clinical conditions is probably similar to the action of other viruses.
Two other studies, conducted in the United States and Israel, also showed an association between myocarditis and Covid-19. The US study, analyzing data from more than 70,000 people, revealed that myocarditis had a probability rate of 8.17%, but an overall risk of 0.1%. According to the authors, although there is an association between the condition and Covid-19, this does not necessarily translate into an overall high risk.