IS IT MEANINGFUL FOR SERUM MYOGLOBIN IN PATIENTS WITH COVID-19 DECREASED?

More than 3 years since cases were first reported, the COVID-19 pandemic remains an acute global emergency. As of April 12, the number of confirmed deaths worldwide was 6,897,025. Since January 8, 2023, based on the evaluation of the virus mutation, prevention, and control situation, according to the Infectious Diseases Prevention and Control Law, COVID-19 disease has been under Category B management in China. The number of COVID-19 cases in Chinese hospitals nationwide peaked (1.625 million) on January 5, 2023, and then decreased continually to 248,000 on January 23, 2023, with an 84.8% reduction from the peak. During the national COVID-19 pandemic in January 2023, we found that serum myoglobin reduced below the reference interval in 956 patients with COVID-19 who presented to the emergency department of our hospital from January 1 to January 31, 2023. So far, no articles specifically reporting the decrease of serum myoglobin in patients with COVID-19 have been retrieved. These 956 patients with low serum myoglobin were identified from 1142 COVID-19 patients who came to the emergency department of our hospital with symptoms of palpitations or chest tightness or chest pain. All 956 patients visited the hospital more than 2 weeks after the first symptoms appeared. The patient's initial symptoms were fever or cough but resolved before they arrived in the emergency department. There were 358 males and 598 females, aged from 14 to 90 years. Electrocardiogram showed no myocardial damage. Chest CT showed no signs of acute pulmonary infection. Cardiac enzymes and blood cell analysis were performed. The reference interval of serum myoglobin in our hospital is 28.0-72.0 ng/ml in males and 25.0-58.0 ng/ml in females. Patient data were obtained from a review of the electronic medical record system. What is the significance of serum myoglobin falling below the reference interval in patients with COVID-19? So far, no reports have been found in the literature. It may have the following implications: 1. Of cardiac biomarkers, an increase in myoglobin could efficiently predict COVID-19 severity in its early stages. Perhaps a decrease in myoglobin also predicts that COVID-19 patients will not have severe myocardial damage later in the disease. 2. Individuals differ widely in the clinical consequences of SARS-CoV-2 infection, from asymptomatic illness to death. Cong Chen et al. have indirectly demonstrated that SARS-CoV-2 can infect human cardiomyocytes. Most markers in the cardiac enzymes and blood cell analysis of 956 patients did not increase, indicating that the SARS-CoV-2 may not cause myocardial damage in these patients, but cardiac nerve function damage in the later stage of the disease, and then cause palpitations and other symptoms, but not serious cardiovascular disease. 3. It is possible that the virus resides somewhere in the body, such as the nerves of the heart, to cause lasting effects. 4. It may help in the research of drugs to treat COVID-19. The serum myoglobin of 956 patients was significantly decreased without myocardial damage, so we speculated that the symptoms of patients such as heart palpitations were caused by the damage of heart nerves caused by SARS-CoV-2. We further speculated that cardiac nerves were potential drug targets for the treatment of COVID-19. Echocardiography was not performed in 956 patients due to emergency department conditions and time constraints. These 956 patients were not hospitalized or followed up because they did not have myocardial injury or acute pneumonia. The emergency department also did not have adequate laboratory conditions for follow-up studies. We hope that the qualified researchers all over the world will continue to study this.