Fatshimetry — Covid-19 may be a powerful risk factor for heart attacks and strokes up to three years after infection, a large new study suggests.
Published Wednesday in the medical journal Atherosclerosis, Thrombosis and Vascular Biology, the study drew on the medical records of about a quarter of a million people enrolled in a vast database called the UK Biobank.
Within that dataset, the researchers identified more than 11,000 people with a positive lab test for Covid-19 in their medical records in 2020; nearly 3,000 of them had been hospitalized for their infections. They compared these groups with more than 222,000 others in the same database who had no previous Covid-19 infection over the same period.
People who got COVID in 2020, before vaccines could blunt the infection, were twice as likely to have a major cardiac event such as a heart attack or stroke, or to die, for nearly three years after their illness, compared with people who did not test positive, the study found.
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, compared with people without COVID in their medical records.
What’s more, for people who did require hospitalization, COVID appeared to be as strong a risk factor for future heart attacks and strokes as diabetes or peripheral artery disease, also known as PAD.
One study estimated that more than 3.5 million Americans were hospitalized with COVID-19 between May 2020 and April 2021.
A finding unique to COVID-19
The increased heart risks from the infection did not appear to abate over time, the study found.
“There’s no evidence that this risk is abatement,” said study author Dr. Stanley Hazen, who chairs the department of cardiovascular and metabolic sciences at the Cleveland Clinic. “This is actually one of the most interesting and surprising findings.”
The finding is striking and appears to be unique to COVID-19, according to Dr. Patricia Best, a cardiologist at the Mayo Clinic in Rochester, Minnesota, who was not involved in the research.
“We’ve known for a while that infections increase the risk of heart attack, so if you get the flu, if you get any type of infection… whether it’s bacterial or viral, it increases your risk of heart attack,” says Dr. Best. “But it usually goes away pretty quickly after infection.
“It’s just such a big effect, and I think it’s just because of how different COVID is from some other infections,” she adds.
The researchers involved in the study say they don’t know exactly why COVID has such long-lasting effects on the cardiovascular system.
Previous studies have shown that the coronavirus can infect cells lining 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 could be that there’s something that COVID does to the artery walls and the vascular system that’s sustained damage and continues to show up over time,” suggests Dr. Hooman Allayee, a professor of biochemistry and molecular genetics at the Keck School of Medicine at the University of Southern California.
Their working hypothesis, Allayee says, is that COVID could destabilize the plaques that form in artery walls and make them more prone to rupture and clot.
Some protective factors
Allayee and her graduate student James Hilser took a closer look at how Covid might cause these long-term problems in the body.
They looked at whether people with known genetic risk factors for heart disease, or genetic changes associated with susceptibility to Covid infection, were more likely than others to have a heart attack, stroke, or die after being hospitalized with Covid. But that wasn’t the case.
What emerged, the researchers said, was a distinction by blood type.
People with certain non-O blood types—A, B, or AB—are known to be at higher risk for cardiovascular disease.
Blood type also appears to play a role in how likely a person is to get Covid. People with type O also appear to have some protection.
In the new study, people with type O who were hospitalized with COVID didn’t have quite as much risk of heart attack or stroke as those with type A, B, or AB. But that doesn’t mean they were exempt, Dr. Hazen said. They still had a higher risk of heart attacks and strokes, but their blood type was just another variable to consider.
The researchers think the gene for blood type may play a role in increasing the risk of heart attacks and strokes after COVID, but they’re not sure exactly how.
Their study also provided some encouraging news. People who were hospitalized with COVID but also took low-dose aspirin didn’t have an increased likelihood of a subsequent heart attack or stroke.