Covid-19 infections could potentially enhance the likelihood of heart attacks, strokes, and mortality for a period of three years post-infection, according to research findings.
The research was published on Wednesday in the journal Atherosclerosis, Thrombosis, and Vascular Biology. It utilized medical records from approximately 250,000 individuals enrolled in a large database known as the UK Biobank.
In this dataset, scientists identified over 11,000 individuals with a positive lab test for Covid-19 recorded in their medical records for 2020, with nearly 3,000 of them being hospitalized due to their infections. These groups were contrasted with over 222,000 others from the same database who did not have a history of Covid-19 throughout the same timeframe.
Individuals infected with Covid-19 in 2020, prior to the availability of vaccines to mitigate the infection, had twice the risk of major cardiac events such as heart attacks, strokes, or death approximately three years after their illness, compared to individuals without a positive test result, according to the study.
Individuals hospitalized due to their infection, indicating a more severe case, had an even greater risk of major heart events – over three times higher – compared to individuals without Covid-19 in their medical records.
Covid-19 appeared to be as potent a risk factor for future heart attacks and strokes as conditions like diabetes or peripheral artery disease (PAD) for individuals hospitalized due to their infection.
Approximately 3.5 million Americans were estimated to have been hospitalized for Covid between May 2020 and April 2021.
Unique aspect of Covid-19
The increased heart risks due to infection did not diminish over time, the study found.
"There's no sign of attenuation of that risk," said study author Dr. Stanley Hazen, who heads the department of Cardiovascular & Metabolic Sciences at the Cleveland Clinic. "That's actually one of the more interesting, I think, surprising findings."
This finding is significant and appears 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.
"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," Best said. "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 than some of the other infections," she said.
The researchers involved in the study are unsure of why Covid-19 has such apparently 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.
"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 destabilizing plaques that are building within the walls of arteries and may make them more prone to rupturing and causing a clot.
Protective factors
Allayee and his graduate student James Hilser investigated further to see how Covid might be causing this long-term damage in the body.
They looked to see if individuals 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. However, they were not.
What did show up, the researchers said, was a distinction by blood type.
Researchers have known that 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 one is to contract Covid. Individuals with O-type blood seem to be a bit protected in this regard as well.
In the new study, individuals with O-type blood who were hospitalized for Covid did not have as high a risk of heart attack or stroke as those with A, B, or AB blood types. However, this does not mean they were entirely safe; 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 play a role in the increased risk of heart attacks and strokes after Covid, but they are unsure of how.
There was some positive news in the study, as well. Individuals 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. This means that the risk can be mitigated, Hazen said.
"Cardiac disease and cardiovascular events are still the number one killer around the world," he said.
When he sees patients, Hazen said, he now makes sure to ask about their Covid history.
"If you’ve had Covid, we have to be especially attentive to making sure that we’re doing everything possible to lower your cardiovascular risk," Hazen said.
That includes controlling blood pressure and cholesterol and perhaps taking a daily aspirin.
The study did not look at the effects of Covid-19 vaccination on an individual's cardiovascular risk, but Hazen suspects that it would be protective, because vaccines usually keep Covid infections from becoming severe.
The investigation failed to explore the possibility of enhanced health issues due to multiple Covid-19 infections, as certain studies suggest.
Regardless, Hazen pointed out that individuals who have been hospitalized due to Covid-19, regardless of vaccination status, should be mindful of heart-related risks.
The study highlights that individuals infected with Covid-19, even after recovery, continue to have an elevated risk of major cardiac events such as heart attacks, strokes, or death compared to those without a positive test result. This long-term heart risk associated with Covid-19 seems to be unique and unlike the transient risk associated with other infections.
The research also suggests that blood type may be a factor in determining the cardiovascular risk for individuals hospitalized due to Covid-19. Individuals with non-O blood types (A, B, or AB) appear to be at higher risk of heart attacks and strokes compared to those with O-type blood, but the exact mechanism behind this is yet to be fully understood.
