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Covid can cause heart problems. Here's how the virus may do its damage.

Scientists who studied human hearts found that infection appeared to make it harder for them to beat properly.
A medical worker treats a Covid patient in the ICU of the General Hospital in La Paz, Bolivia in 2021.
A medical worker treats a Covid patient in the intensive care unit at General Hospital in La Paz, Bolivia, in 2021.Juan Karita / AP file

Covid can cause damage to the heart on a cellular level that can lead to lasting problems, including irregular heartbeats and heart failure, preliminary research suggests.

Covid’s effects on the heart have been well documented, but a new study zooms in on the microscopic changes thought to be caused by the virus.  

Researchers from Columbia University in New York City examined autopsied heart tissue from people who had Covid, and found that the infection damaged the way cells in the heart regulate levels of calcium, a mineral that plays an important role in how the organ contracts and pumps blood throughout the body. In another part of the study, the same damage was seen in mice with Covid.

The findings, presented Monday at the Biophysical Society Meeting in San Diego, have not yet been published in a peer-reviewed journal.

When a person is infected with Covid, the immune system launches a hefty inflammatory response in an effort to fight off the virus. That inflammation, the new study found, disrupts how calcium is stored in the heart. 

Calcium ions — a version of the element that carry a positive charge — are important messengers that regulate heart function, including how quickly and how forcefully the organ contracts. These ions are stored inside cells, on deck for when the body needs to use them. They’re released through channels in the cellular membrane, which ensures that just the right amount of calcium can get out. 

The damage caused by inflammation during a Covid infection appears to prop these channels open, letting too much calcium leak from the cells of the heart, said Dr. Andrew Marks, a cardiologist and biophysics professor at Columbia University who co-led the study. This flood of calcium, he said, can decrease heart function and even cause fatal arrhythmias, or irregular heartbeats. 

Although inflammation of the heart is a rare but documented side effect of the mRNA Covid vaccines, the study looked only at heart tissue from autopsies before vaccines were available. 

“Whatever changes we saw were because of infection,” Marks said, adding that the new study was small, and the next step was to conduct the research on a larger scale. 

Calcium also plays an important role in the brain

The findings built on something Marks and his team had observed earlier in the pandemic when they were investigating how Covid affects another organ: the brain.

In a study published in 2021 in the journal Alzheimer’s and Dementia, the team found the same cellular damage to calcium ion channels in autopsied brain tissue of people who had been infected with Covid. These changes, Marks noted, had long been seen in people with Alzheimer’s disease.

Dr. Siddharth Singh, clinical director of the post-Covid-19 cardiology clinic at the Smidt Heart Institute at Cedars-Sinai Medical Center in Los Angeles, said the latest findings help explain the heart and brain problems seen in Covid patients. 

“Calcium is an essential mineral for life,” said Singh, who was not involved with the research.

“This may put things together for the heart and the brain.” 

Viral infections causing inflammation of the heart is not a new finding. 

“Before Covid came onto the scene, during the winter, when viral infections would spike, we would see more people presenting with things like myocarditis,” said Singh, referring to inflammation of the heart lining. 

He said the damage wasn’t necessarily permanent. “Over time, symptoms like brain fog and palpitations do get better in some patients, so to an extent, this damage appears to be able to heal,” he said, adding that patients need to be studied longer for researchers to understand exactly what factors allow this to happen. 

Dr. Nicholas Hendren, a cardiologist at UT Southwestern Medical Center in Dallas, said: “Once this is better understood, we may be able to develop therapies to treat this damage and potentially a therapy to protect the heart and cardiovascular system from damage from Covid.” Hendren was also not involved in the new research. 

Can vaccines protect against heart damage from Covid?

Another new study, published Monday in the Journal of the American College of Cardiology, suggests that vaccination may protect against major cardiovascular events — like heart attacks and strokes — associated with Covid. 

The study analyzed data from nearly 2 million people in the National Covid Cohort Collaborative database. About 218,000 had received at least one dose of either the Pfizer-BioNTech or Moderna mRNA vaccine, or Johnson & Johnson’s single dose vaccine. Even partial vaccination was associated with lower risk of cardiovascular events for at least six months, the researchers found. 

More research is needed to confirm whether Covid vaccination reduces the risk of these cardiovascular events, but the new study begins to broaden the understanding of the unknown long-term effects vaccines may have on the heart. 

“There have been a lot of various messages about the efficacy of vaccines,” said study co-author Joy Jiang, an M.D./Ph.D. candidate at the Icahn School of Medicine at Mount Sinai in New York City. “This pushes the narrative toward encouraging people to get vaccinated because of this associated benefit.” 

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