Reacción a "Reaction to study analysing the prevalence of acute myocarditis in covid-19 patients"

The mortality rate of covid-19 is estimated to be less than 1%, and is mainly due to severe acute respiratory syndrome and multi-organ dysfunction. However, cardiovascular complications of covid-19 have received less medical attention despite the fact that myocarditis has been recognised as a cause of death in some covid-19 patients. This is probably due to the lack of comprehensive studies on the prevalence of myocarditis as a consequence of covid-19.

The present retrospective study was conducted in 23 hospitals in the United States and Europe and included 56,963 covid-19 patients. The result provides fairly strong evidence that the prevalence of myocarditis in people with covid-19 is around 2.4 per 1,000 hospitalisations. Of particular relevance is the fact that approximately 39% of these patients developed fulminant myocarditis requiring temporary inotropic or mechanical support. In addition, the mortality of these patients during hospitalisation was 20 %.

It is established that the pathophysiology of covid-19-related myocarditis is a combination of direct viral injury and cardiac damage due to the host immune response. However, the study of this pathology in the pandemic has been hampered by problems in reaching an accurate diagnosis of myocarditis. Today the gold standard technique for the diagnosis of acute myocarditis remains endomyocardial biopsy, but it is not routinely performed in clinical practice because it is a highly invasive test and carries a number of risks to the patient. In addition to biopsy, cardiac magnetic resonance imaging is used in routine clinical practice to diagnose this pathology, but it is an expensive technique that is not available in all hospitals. In this study, both biopsy and cardiac MRI have been used to diagnose myocarditis, allowing us to establish the approximate prevalence of this serious cardiac complication in covid-19 patients.

This is a retrospective study, so there could be a bias in patient selection. Furthermore, of the patients with myocarditis included, only 17 were diagnosed with the gold standard technique, endomyocardial biopsy, which could lead to confusion in the inclusion and final diagnosis of the remaining patients included, even though their final diagnosis was made with magnetic resonance imaging, which is the technique most commonly used in clinical practice. 

The study shows that acute myocarditis is a possible clinical entity associated with covid-19. This heart disease may or may not present in association with pneumonia, although concomitance of both has a worse prognosis. The use of corticosteroids in these patients with myocarditis appears to be safe as in most cases it restores left ventricular function. These findings are useful in clinical practice, and encourage physicians to make more accurate diagnoses in patients with covid-19 who present with chest pain, dyspnoea or elevated troponins.