Severe Lung Infection from Covid-19 Can Damage the Heart
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SARS-CoV-2, the virus that causes Covid-19, can damage the heart even without directly infecting the heart tissue. This NIH-funded study, published in the journal Circulation, specifically looked at damage to the hearts of people with SARS-CoV-2-associated acute respiratory distress syndrome (ARDS), a serious lung condition that can be fatal. But researchers said the findings could have relevance to organs beyond the heart and also to viruses other than SARS-CoV-2.
Prior imaging has shown that more than 50% of people who have severe Covid-19 infections experience some inflammation or damage to the heart. Scientists did not know, however, whether the damage occurs because the virus infects the heart tissue itself, or due to systemic inflammation triggered by the body’s well-known immune response to the virus.
Researchers focused on immune cells known as cardiac macrophages, which normally perform a critical role in keeping the tissue healthy but can turn inflammatory in response to injury such as heart attack or heart failure. Researchers analyzed heart tissue specimens from 21 patients who died from SARS-CoV-2-associated ARDS and compared them with specimens from 33 patients who died from non-Covid-19 causes. They also infected mice with SARS-CoV-2 to follow what happened to the macrophages after infection.
In both humans and mice, scientists found the SARS-CoV-2 infection increased the total number of cardiac macrophages and also caused them to shift from their normal routine and become inflammatory.
“This study shows that after a Covid infection, the immune system can inflict remote damage on other organs by triggering serious inflammation throughout the body—and this is in addition to damage the virus itself has directly inflicted on the lung tissue,” said senior study author Dr. Matthias Nahrendorf of Harvard Medical School. “These findings can also be applied more generally, as our results suggest that any severe infection can send shockwaves through the whole body.”