Getting COVID-19 is heartbreaking news for anyone. But a new study reveals that the disease is heartbreaking in more ways than one, especially since it's been found to tear heart muscles to shreds – at least in vitro.
The ability of SARS-CoV-2 – the virus behind the deadly pandemic – to invade the heart muscle and effectively "dice" it is already scary enough. However, the authors of the study warned that a similar process could be happening in the hearts of COVID-19 patients.
The study, led by researchers from the University of California, San Francisco, has been published to the preprint database bioRXiv. It has not been published in a peer-reviewed journal, or proven to happen in people.
SARS-CoV-2 can rip your heart into shreds
The study's findings were so alarming that Tom McDevitt, a bioengineering professor at UCSF's Gladstone Institute and senior author of the study, had trouble sleeping for nights afterward. He also noted that COVID-19 is possibly the only disease to affect heart cells in this manner.
"What we were seeing was completely abnormal," McDevitt added.
The study is still in preprint, but McDevitt said that he and his team felt compelled to share their findings as soon as possible. He added that while their study might not provide a whole picture, it may provide clinicians with insights to the extent of SARS-CoV-2’s damage in a patient's cardiovascular system. The findings can also explain why COVID-19 is particularly risky for those with cardiovascular disease, which already accounts for a third of all deaths around the world. It can even help doctors understand why some COVID-19 cases have heart abnormalities – including inflammation – even in relatively mild cases.
After exposing different types of heart cells to SARS-CoV-2, the team found that the virus could only infect and make copies of itself inside heart muscle cells, or cardiomyocytes. These cells contain sarcomeres – specialized filaments that are responsible for muscle contractions that produce a heartbeat. They found that heart muscle cells infected by SARS-COV-2 had their sarcomeres chopped into small fragments. This would make it impossible for the heart muscle to beat properly, the researchers added.
The team also studied autopsy samples of heart tissue from three COVID-19 patients and found sarcomere filaments that were disordered and rearranged in a pattern similar to that in their lab dish experiments. More studies, they added, are needed to determine if these changes are permanent. For one, this requires doing a special process to examine the sarcomeres. With their findings, the team hopes that doctors will look for these features in their own cases.
The research team also found that some infected heart cells did not have DNA inside their cells' nucleus. This effectively makes the cells "brain dead" and unable to perform normal functions.
“Cell nuclei – the hubs of all the genetic information, all of the nuclear DNA – in many of the cells were gone,” McDevitt added. “There was a black hole literally where we would normally see the nuclear DNA. That’s also pretty bizarre.”
The damage that COVID-19 does to the heart is something that's been seen in patients, regardless of their health. Dr. Ossama Samuel, a cardiologist at Mount Sinai Hospital in New York City who wasn't part of the study, said that his team has treated healthy people who recovered from COVID-19 who have developed myocarditis afterward.
Myocarditis – the inflammation of the heart muscle – can impair the heart's ability to pump blood. According to healthcare experts, severe cases of myocarditis can significantly weaken the heart so that the rest of the body can't get enough blood. This can ultimately lead to a stroke, or even a heart attack.
Like McDevitt, Samuel thinks that a small fraction of people with COVID-19 also sustain heart damage. (Related: Can heart enlargement predict coronavirus deaths?)
“When a disease is so widespread it is concerning that a tiny fraction is still sizable,” he added.
He also says that athletes, in particular, have a high risk of dying from COVID-19-related myocarditis through exercise or training. In fact, an Ohio State University cardiologist says that up to 13 percent of athletes who recover from COVID-19 may have myocarditis.
For his part, McDevitt warns that the risk of getting heart disease from COVID-19 is serious and that people should take their findings into account as they assess their own risk of being infected with COVID-19.
“I am more scared today of contracting the virus, by far, than I was four months ago,” he said.
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