SARS-CoV-2 infects cardiomyocytes through an ACE2 and endosomal inflammatory infiltrate.
In a study conducted by the Washington University School of Medicine, investigators have provided evidence that COVID-19 can damage heart muscle and interfere with contractions. They discovered that the damage is caused by the virus replicating inside heart muscle cells, which leads to cell death. Results from the study were published in the Journal of the American College of Cardiology: Basic to Translational Science.
COVID-19 has been known to have some effect on the heart and has been associated with a reduced ability to pump blood and abnormal heart rhythms. However, it has never been clear whether these problems arise due to the infection or the inflammatory response to the virus.
"Early on in the pandemic, we had evidence that this coronavirus can cause heart failure or cardiac injury in generally healthy people, which was alarming to the cardiology community," Kory J. Lavine, senior author on the study said. "Even some college athletes who had been cleared to go back to competitive athletics after COVID-19 infection later showed scarring in the heart. There has been debate over whether this is due to direct infection of the heart or due to a systemic inflammatory response that occurs because of the lung infection.”
The investigators behind the study used stem cells to create heart tissue that can model an infection as well as how the heart contracts, enabling them to study COVID-19 progression within a human heart.
Findings from the study showed a viral infection with COVID-19 kills heart muscle cells and destroys the muscle fiber units that are responsible for contractions within the heart muscle. Additionally, the team discovered that this type of cell death and loss of muscle fiber can happen even when there is no inflammation.
"COVID-19 is causing a different immune response in the heart compared with other viruses, and we don't know what that means yet," Lavine said. "In general, the immune cells seen responding to other viruses tend to be associated with a relatively short disease that resolves with supportive care. But the immune cells we see in COVID-19 heart patients tend to be associated with a chronic condition that can have long-term consequences. These are associations, so we will need more research to understand what is happening."