Myocarditis: A complication of COVID-19 and long-COVID-19 syndrome as a serious threat in modern cardiology.

Myocarditis is the inflammation of the heart muscle and is usually a consequence of a viral infection [1]. Because this disease can cause the destruction of myocytes, it may result in cardiomyopathy, heart failure, and sudden cardiac death. Cardiovascular complications from coronavirus disease 2019 (COVID-19) are emerging [2], especially during hospitalization, and myocarditis has been identified as a cause of death in some COVID-19 patients [3]. In the current epidemiological situation of a very large number of hospitalized patients, we must consider the long-term effects of myocarditis caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Initial reports based on magnetic resonance imaging studies showed 78% of patients with myocardial abnormalities and 60% with ongoing myocarditis 2 to 3 months after COVID-19 infection. High blood troponin concentrations were also found in 76% of patients, although their heart function was preserved [4]. In other studies, about 10 weeks after SARS-CoV-2 infection, 37% of patients were also diagnosed with myocarditis, despite only half of the respondents having symptoms of COVID-19 infection [5]. In contrast, the most recent reports that analyzed data for a fifth of the United States (US) population showed that males between 12 and 17 years of age most likely developed myocarditis within 3 months of SARS-CoV-2 infection, with an incidence of approximately 450 per million infections. The most recent CDC reports, indicating the number of infected teenagers in the US is the highest in all age groups, suggest that myocarditis will become a significant burden [6]. The reports also estimate a 16 times higher risk in patients with COVID-19 compared to the general population, with an incidence of COVID-19-associated myocarditis of approximately 150 cases per 100,000 [7].

In light of these numbers, cardiac complications both during and after the SARS-CoV-2 infection will become a significant burden. Currently, the only effective method of preventing COVID-19 complications is vaccination, which reduces not only the risk of infection and mortality but also its long-term complications, i.e., long-COVID-19. In a study of 971,504 fully vaccinated people, only 0.2% developed COVID-19 symptoms, and only 31 developed long-COVID-19. On the other hand, the rate of COVID-19 infections was 11% in the unvaccinated group [8].

There is a lessor need to focus on myocarditis following mRNA vaccination [9]. This is because the infection and hospitalization rates are 17 times lower when compared to the unvaccinated group [10]. In summary, it is necessary to vaccinate the whole of society as soon as possible, perform further research on myocarditis in long-COVID-19 syndrome, create effective screening systems, and provide care for people suffering from long-COVID-19 syndrome before it leads to more serious complications.