A large study has suggested that Covid-19 could be a powerful risk factor for heart attacks and strokes for as long as three years after an infection, according to the researchers.
The paper, published in the Atherosclerosis, Thrombosis and Vascular Biology, relied on medical records from a quarter of a million people enrolled in the UK Biobank.
Of the more than 11 000 who had a positive lab test for Covid-19 documented in their medical records in 2020, nearly 3 000 had been admitted to hospitals for their infections.
CNN reports that the researchers compared these groups with more than 222 000 others in the same database who didn’t 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 didn’t test positive, the study found.
If a person had been hospitalised for their infection, pointing to a more severe case, the risk of a major heart event was even greater – more than three times higher – than for those without Covid in their medical records.
Additionally, for people who needed to be hospitalised, Covid 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 3.5m Americans were hospitalised 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.
“There’s no sign of attenuation of that risk,” said study author Dr Stanley Hazen, who chairs the department of Cardiovascular & Metabolic Sciences at the Cleveland Clinic. “That’s one of the more interesting and surprising findings.”
That finding is striking and seems to be unique to Covid-19, said Dr Patricia Best, a cardiologist at the Mayo Clinic in Minnesota, who was not involved in the research.
“We 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 it’s bacterial or viral, that increases your risk of having a heart attack. But it generally goes away pretty quickly after your infection.
“This is just such a large effect, and I think it’s just because of how different Covid is from some of the other infections,” she said.
The researchers involved in the study don’t know exactly why Covid appears to have such long-lasting effects on the cardiovascular system.
Earlier studies have shown that the coronavirus can infect the 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.
“There 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,” 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 destabilising 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 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 hospitalised for Covid. But they weren’t.
What did show up, they say, was a distinction by blood type.
Researchers have known that people with certain non-O blood types – A, B or AB – are at higher risk of cardiovascular diseases.
Blood type also appears to play a role in how likely a person is to get Covid. People with O-type blood seem to be a bit protected there, too.
In the latest study, people with O-type blood who were hospitalised for Covid didn’t have quite as high of a risk of heart attack or stroke as those with A, B or AB blood types. But that doesn’t 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 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 aren’t sure exactly how.
There was some hopeful news in the study, too. People who were hospitalised 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.
“Cardiac disease and cardiovascular events are still the number one killer around the world.”
When he sees patients, Hazen added, he now makes sure to ask about their Covid history.
“If they’ve had Covid, we are especially attentive to making sure we’re doing everything possible to lower any cardiovascular risk,” he said.
That includes controlling blood pressure and cholesterol and perhaps taking a daily aspirin.
The study didn’t look at the effects of Covid-19 vaccination on a person’s cardiovascular risk, but Hazen suspects that it would be protective, because vaccines usually keep Covid infections from becoming severe.
The study also didn’t 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 hospitalised for Covid – whether vaccinated or not – should be attentive to their heart risks.
Study details
Covid-19 Is a Coronary Artery Disease Risk Equivalent and Exhibits a Genetic Interaction With ABO Blood Type
Abstract
Background
Covid-19 is associated with acute risk of major adverse cardiac events (MACE), including myocardial infarction, stroke, and mortality (all-cause). However, the duration and underlying determinants of heightened risk of cardiovascular disease and MACE post–Covid-19 are not known.
Methods
Data from the UK Biobank was used to identify Covid-19 cases (n=10 005) who were positive for polymerase chain reaction (PCR+)-based tests for SARS-CoV-2 infection (n=8062) or received hospital-based International Classification of Diseases version-10 (ICD-10) codes for Covid-19 (n=1943) between February 1, 2020 and December 31, 2020. Population controls (n=217 730) and propensity score—matched controls (n=38 860) were also drawn from the UK Biobank during the same period. Proportional hazard models were used to evaluate Covid-19 for association with long-term (>1000 days) risk of MACE and as a coronary artery disease risk equivalent. Additional analyses examined whether Covid-19 interacted with genetic determinants to affect the risk of MACE and its components.
Results
The risk of MACE was elevated in Covid-19 cases at all levels of severity (HR, 2.09 [95% CI, 1.94–2.25]; P<0.0005) and to a greater extent in cases hospitalised for Covid-19 (HR, 3.85 [95% CI, 3.51–4.24]; P<0.0005). Hospitalisation for Covid-19 represented a coronary artery disease risk equivalent since incident MACE risk among cases without history of cardiovascular disease was even higher than that observed in patients with cardiovascular disease without Covid-19 (HR, 1.21 [95% CI, 1.08–1.37]; P<0.005). A significant genetic interaction was observed between the ABO locus and hospitalisation for Covid-19 (Pinteraction=0.01), with risk of thrombotic events being increased in subjects with non-O blood types (HR, 1.65 [95% CI, 1.29–2.09]; P=4.8×10−5) to a greater extent than subjects with blood type O (HR, 0.96 [95% CI, 0.66–1.39]; P=0.82).
Conclusions
Hospitalisation for Covid-19 represents a coronary artery disease risk equivalent, with post–acute myocardial infarction and stroke risk particularly heightened in non-O blood types. These results may have important clinical implications and represent, to our knowledge, one of the first examples of a gene-pathogen exposure interaction for thrombotic events.
See more from MedicalBrief archives:
Blood clot risk still high months after Covid – Bristol University study
Scientists probe link between COVID symptoms, blood clots
Preliminary results from two UK studies suggest significant heart inflammation from Covid