Researchers from the D’Or Institute for Research and Education (IDOR) with other national institutions and the University of Colorado Boulder published in the scientific journal Hypertension of the American Heart Association a study that evaluated the systemic effects, in other words, on the entire human body of acute SARS-CoV-2 infection, in survivors of severe forms of covid-19. 

Nineteen people participated in the study without covid-19 infections, and other 19 were hospitalized in wards or intensive care units (ICU) during the acute phase (when the patient has severe symptoms) of the covid-19 infection. 

The study demonstrated that patients have an increase in muscular sympathetic nervous activity, even three months after hospitalization, which is a risk factor for survival in different types of illnesses, including those that affect the heart and the respiratory system. The sympathetic nervous system is responsible for, among other functions, regulating blood pressure, heart rate, and the action of the smooth muscle present in the blood vessels that irrigate our body’s tissues. In addition, the researchers also observed vascular dysfunction, characterized by increased stiffening of the aorta and damage to the functioning of the endothelial cells that line the inner walls of the arteries, which can contribute to the risk of cardiovascular diseases such as heart attack. 

When assessing cardiac alterations, the study demonstrated that the patients presented alterations in diastolic heart function, which is responsible for the entry of blood flow into the heart. It was also observed that this group had other altered parameters like larger myocardial performance and bigger left atrium. It is noteworthy that the surviving covid-19 patients did not have cardiovascular diseases, and both groups had similar blood pressure. The authors suggest that these clinical alterations still need to be investigated as transient or if they are the effects of a long-term post-acute infection, because there is no right ventricular dysfunction or cardiac biomarkers such as pro-BNP or Troponin I, indicative of cardiac insufficiency. 

When the researchers evaluated the patient’s ability to perform the physical exercise at maximum intensity, was also observed that the maximum oxygen consumption in the group of survivors was lower than compared to the control, even with similar physical effort. This fact could be linked to high muscle sympathetic nerve activity, vascular dysfunction and changes in diastolic heart function, generating vasoconstriction that results in impaired muscle blood flow, in other words, less oxygenation in the muscles. In view of this, it was possible to demonstrate that the decrease in the exercise capacity of this group was mainly related to the deconditioning of the skeletal muscle since this is responsible for executing the body’s movements. 

The authors emphasize the importance of cardiovascular evaluation in conditions of stimuli or excitation of the cardiovascular system, such as stressful situations, since the study was conducted at rest. However, even without this observation, other findings in the literature suggest that covid-19 survivors have abnormal cardiovascular responses to a stressful stimulus. The study’s findings reveal greater muscle sympathetic neural activity, increased central arterial stiffness, reduced vascular endothelial function, alterations in cardiac functioning associated with reduced capacity to perform aerobic exercise. 

The study’s next step is to assess whether these patients remain with these changes 12 months after hospital discharge. Furthermore, this group will participate in cardiopulmonary rehabilitation, as physical training improves vascular function. This therapy may provide important answers for the rehabilitation of patients with long-term Covid-19, may contribute to improving the quality of life in this population, say the researchers.