COVID-19 could be a powerful risk factor for heart attacks and strokes for as long as three years after an infection, a large new study suggests.
The study was published Wednesday in the medical journal Atherosclerosis, Thrombosis, and Vascular Biology. It relied on medical records from roughly a quarter of a million people who were enrolled in a large database called the U.K. Biobank.
Within this dataset, researchers identified more than 11,000 people who had a positive lab test for COVID-19 documented 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 didnât have a history of COVID-19 over the same time frame.
People who caught COVID in 2020, before there were vaccines to blunt the infection, had twice the risk of a major cardiac event like a heart attack or stroke or death for almost three years after their illness, compared with the people who didnât test positive, the study found.
If a person had been hospitalized for their infection, pointing to a more severe case, the risk of a major heart event in was even greater â more than three times higher â than for people without COVID in their medical records.
Whatâs more, for people who needed to be hospitalized, COVID appeared to be as potent a risk factor for future heart attacks and strokes as diabetes or peripheral artery disease, or PAD.
One that more than 3.5 million Americans were hospitalized for COVID between May 2020 and April 2021.
A finding unique to COVID-19
The elevated heart risks from infection did not appear to diminish over time, the study found.
âThereâs no sign of attenuation of that risk,â said study author Dr. Stanley Hazen, who chairs the department of Cardiovascular & Metabolic Sciences at the Cleveland Clinic. âThatâs actually one of the more interesting, I think, surprising findings.â
That finding is striking and seems to be unique to COVID-19, said Dr. Patricia Best, a cardiologist at the Mayo Clinic in Rochester, Minnesota, who was not involved in the research.
âWe have known for some time that infections raise your risk of having a heart attack, so that if you have influenza, if you get any kind of infection ⌠whether itâs bacterial or viral, that increases your risk of having a heart attack,â Best said. âBut it generally goes away pretty quickly after your infection.
âThis is just such a large effect, and I think itâs just because of how different COVID is than some of the other infections,â she said.
The researchers involved in the study say they donât know exactly why COVID has such apparently long-lasting effects on the cardiovascular system.
Earlier 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.
âThere might just be something that COVID does to the artery walls and the vascular system that is sustained damage and just continues to manifest over time,â said study author Dr. Hooman Allayee, a professor of biochemistry and molecular genetics at the Keck School of Medicine at the University of Southern California.
Their working theory, Allayee said, is that COVID may be destabilizing plaques that are building within the walls of arteries and may make them more prone to rupturing and causing a clot.
Some protective factors
Allayee and his graduate student James Hilser took a closer look to see how COVID might be causing this long-term trouble in the body.
They looked to see whether people with known genetic risk factors for heart disease, or gene changes linked to being susceptible to COVID infection, were more likely than others to have a heart attack or stroke or to die after being hospitalized for COVID. But they werenât.
What did show up, the researchers say, was a distinction by blood type.
Researchers have known that people with certain non-O blood types â A, B or AB â are of cardiovascular diseases.
Blood type also in how likely a person is to get COVID. People with O-type blood seem to be a bit protected there, too.
In the new study, people with O-type blood who were hospitalized for COVID didnât have quite as high of a risk of heart attack or stroke as those with A, B or AB blood types. But that doesnât mean they were in the clear, Hazen said: They were still at higher risk of heart attacks and strokes, but their blood type was just another variable to consider.
The researchers believe that the gene that codes for blood type may be playing a role in the increased risk in heart attacks and strokes after COVID, but they arenât sure exactly how.
There was some hopeful news in the study, too. People who were hospitalized for COVID but who were also taking low-dose aspirin had no increase in the likelihood of a subsequent heart attack or stroke. That means the risk can be mitigated, Hazen said.
âCardiac disease and cardiovascular events are still the number one killer around the world,â he said.
When he sees patients, Hazen said, he now makes sure to ask about their COVID history.
âIf youâve had COVID, we have to be especially attentive to making sure that weâre doing everything possible to lower your cardiovascular risk,â Hazen said.
That includes controlling blood pressure and cholesterol and perhaps taking a daily aspirin.
The study didnât look at the effects of COVID-19 vaccination on a personâs cardiovascular risk, but Hazen suspects that it would be protective, because vaccines usually keep COVID infections from becoming severe.
The study also didnât dig into whether repeated COVID infections might be tied to even greater health risks, as some research has found.
Still, Hazen said, anyone who was hospitalized for COVIDâ whether vaccinated or not â should be attentive to their heart risks.