(CNN) – Covid-19 could be a major risk factor for heart attacks and strokes up to three years after an infection, a large new study suggests.
The study, published Wednesday in the medical journal Atherosclerosis, Thrombosis and Vascular Biology, was based on the medical records of about a quarter of a million people who were enrolled in a large database called UK Biobank.
In this data set, the researchers identified more of the 11,000 people who had a positive laboratory test result for Covid-19 documented in their medical records in 2020, nearly 3,000 of whom had been hospitalized for the disease. They compared these groups to more than 222,000 other people in the same database who had no history of Covid-19 during the same time period.
People who contracted Covid in 2020, before vaccines existed to mitigate the infection, had twice the risk of suffering a major cardiac event, such as a heart attack or stroke, or dying for almost three years after their disease, compared to people who did not test positive.
If a person had been hospitalized for their infection, indicating a more severe case, the risk of a major cardiac event was even higher, more than three times higher than for people without Covid-19 in their medical records.
What’s more, for people who needed to be hospitalized, Covid-19 appeared to be as potent a risk factor for future heart attacks and strokes as diabetes or peripheral artery disease, or PAD.
One study estimated that more than 3.5 million Americans were hospitalized for Covid-19 between May 2020 and April 2021.
The report found that elevated heart risks from infection did not appear to decrease over time.
“There are no signs of attenuation of that risk,” said study author Dr. Stanley Hazen, who chairs the department of Cardiovascular and Metabolic Sciences at the Cleveland Clinic. “That’s actually one of the most interesting and surprising findings.”
That finding is surprising and appears to be unique to Covid-19, explained Dr. Patricia Best, a cardiologist at the Mayo Clinic in Rochester, Minnesota, who was not involved in the research.
“We’ve known for some time that infections increase the risk of having a heart attack, so if you have the flu, if you get any type of infection…whether it’s bacterial or viral, that increases your risk of having a heart attack,” he said. Best. “But it usually goes away pretty quickly after infection.
“This is such a large effect and I think it’s just because of how different Covid is from some of the other infections,” he said.
Researchers involved in the study say they don’t know exactly why Covid has such apparently long-lasting effects on the cardiovascular system.
Previous studies have shown that the coronavirus can infect the cells that line the walls of blood vessels. The virus has also been found in sticky plaques that form in arteries that can rupture and cause heart attacks and strokes.
“It may be that Covid-19 does something to the walls of the arteries and the vascular system, which is sustained damage that continues to manifest over time,” said study author Dr. Hooman Allayee, professor of biochemistry and molecular genetics at the Keck School of Medicine of the University of Southern California.
Their working theory, Allayee said, is that Covid-19 may be destabilizing plaques that are forming inside the walls of arteries and may make them more likely to rupture and cause a clot.
Allayee and his graduate student James Hilser took a closer look at how Covid-19 could be causing this long-term problem in the body.
They sought to see whether people with known genetic risk factors for heart disease or genetic changes related to susceptibility to infection with this virus were more likely than others to have a heart attack or stroke or to die after being hospitalized with Covid. -19. But it wasn’t like that.
What was detected, the researchers say, was a distinction based on blood type.
Researchers knew that people with certain non-O blood types (A, B, or AB) have a higher risk of cardiovascular disease.
Blood type also appears to influence a person’s likelihood of contracting Covid-19. People with type O blood also seem to be a bit protected in that regard.
In the new study, people with type O blood who were hospitalized for coronavirus did not have as high a risk of having a heart attack or stroke as patients with blood types A, B or AB. But that doesn’t mean they were safe, Hazen said, adding that they were still at higher risk for heart attacks and strokes, but their blood type was just another variable to consider.
Researchers believe the gene that codes for blood type may be influencing the increased risk of heart attacks and strokes after Covid-19 but they are not sure exactly how.
The study also provided some hopeful news. People who were hospitalized for Covid-19 but also took low-dose aspirin did not have an increased chance of having a subsequent heart attack or stroke. That means the risk can be mitigated, Hazen said.
“Heart disease and cardiovascular events remain the leading cause of death worldwide,” he noted.
When he sees patients, Hazen said, he now makes sure to ask them about their Covid-19 history.
“If you have had Covid-19, we need to be especially vigilant to make sure we are doing everything we can to reduce your cardiovascular risk,” he said.
That includes monitoring blood pressure and cholesterol and perhaps taking a daily aspirin.
The study did not look at the effects of Covid-19 vaccination on a person’s cardiovascular risk, but Hazen suspects it would be protective, because vaccines generally prevent Covid-19 infections from getting worse.
The study also did not investigate whether repeated infections with this disease could be linked to even greater health risks, as some research has found.
Still, Hazen said, anyone who has been hospitalized with Covid-19, whether vaccinated or not, should be aware of their cardiac risks.
