Seeking to clarify connections between pre-existing heart disease and
COVID-19, a study of critically ill patients has found their risk of
dying from COVID-19 may stem not directly from heart disease, but from
the factors that contribute to it.
People with heart disease have
been, and continue to be, at higher risk of developing severe COVID-19,
according to the Centers for Disease Control and Prevention. The new
study, published Tuesday in the American Heart Association journal Circulation: Cardiovascular Quality and Outcomes,
suggests cardiovascular risk factors – such as being older and whether a
person smoked – were the main contributors to serious illness, rather
than heart disease itself.
COVID-19 is known to cause organ
damage through uncontrolled inflammation. Inflammation also is common in
people with heart disease and stroke, and it's associated with smoking
and other cardiovascular disease risk factors such as high blood
pressure and diabetes.
To understand the connections, researchers
looked at the records of 5,133 critically ill COVID-19 patients who
were part of a collaborative study called STOP-COVID. The patients came
from 68 hospitals across the U.S. and were admitted to ICUs between
March 1 and July 1, 2020.
Of those, 1,174 had pre-existing
cardiovascular disease, defined in the study as including coronary
artery disease (plaque in the heart's arteries), heart failure (where
the heart fails to pump effectively) or atrial fibrillation (a type of
irregular heartbeat).
Having pre-existing cardiovascular disease
initially appeared to be a risk factor for dying within 28 days of
hospital admission for COVID, said senior author Dr. Salim Hayek. He's
an assistant professor at the University of Michigan in Ann Arbor, where
he's director of the Frankel Cardiovascular Center.
But when
researchers separated out things associated with cardiovascular disease,
such as age, high blood pressure and diabetes, the link between
cardiovascular disease itself and death from COVID appeared to be
statistically insignificant.
The researchers found the most
important risk factors for death to be, in order, age, body mass index
(a measure of obesity), race and ethnicity, and history of smoking.
The
results suggest the increased risk of death among heart disease
patients studied is less that they have plaque-lined arteries, and more
that they have risk factors contributing to COVID-19's
hyperinflammation, Hayek said. He acknowledged, however, that because
the study had few people with heart transplants or severe cardiovascular
disease, such as advanced heart failure, the researchers could not draw
conclusions about them.
In a second part of their analysis, the
researchers looked at a biomarker for heart damage called troponin.
Troponin is commonly used as a test for whether someone has had a heart
attack. But, Hayek said, it also can indicate stress on the
cardiovascular system or cardiac injury as the body struggles with a
COVID-19 infection.
Among the 2,741 patients for whom troponin
levels were available, "cardiac injury was a strong predictor of bad
outcomes," Hayek said – regardless of whether the patient had
cardiovascular disease. The higher the troponin level, the more likely a
patient would die. "Essentially, what we're seeing here is that cardiac
injury is a surrogate marker for the severity of the COVID-19 illness,"
he said.
Summing up, Hayek said, the first part of the study
"highlights that it's not the pre-existing cardiac disease. And the
second part highlights that cardiac injury is linked to worse outcomes."
Together, that suggests the cardiac injury is probably related to the
stress of the acute COVID-19 illness rather than a sign of new
complications of cardiovascular disease.
He said the study
emphasizes that severe COVID-19 is a hyperinflammatory process – and
that the inflammatory processes linked to cardiovascular risk also put
people at risk of having severe COVID.
The study does not mean
that someone with existing cardiovascular disease can ignore the
problem, Hayek said. Instead, people need to think about those shared
risk factors.
Dr. Tracy Y. Wang, a professor of medicine in cardiology at Duke University in Durham, North Carolina, agreed.
People
with heart disease are still at higher risk of dying from COVID-19,
said Wang, who was not involved in the research. But the study helps
clarify what's harming people.
"It's not so much about the fact
that they previously had heart disease," she said. "It's about their
overall health status that makes them higher risk. So that distinction I
think is really interesting."
The association between cardiac
injury and death "seems like a bit of a no-brainer," she said. Severe
COVID-19 causes damage everywhere, not just the heart. "Patients who die
tend to have more organ hits, so to speak," she said. Troponin levels
would be just one more marker of the fact that they're sick.
She noted that "a good chunk of these patients never had troponin measured," which makes it harder to draw conclusions.
But she said the findings, overall, offered a bit of a silver lining to patients.
"It's
saying not all hope is lost even if you've had prior heart disease,"
she said. These results suggest that if researchers can learn how to
limit levels of heart damage, "then we have a much better chance of
having patients survive their ICU stay, and hopefully have better
quality of life and longevity after this as well."
Regardless of
whether they've been diagnosed with heart disease, people could think
about the findings as a way of inspiring self-care, Wang said. "If you
can practice good preventive therapy – see a doctor regularly, keep your
diabetes under control, aim for a healthy weight, aim for an active
lifestyle – the combination of all of those things should not only limit
your risk of developing heart disease, that also would help keep your
disease severity lower and your risk of adverse outcomes lower even if
you were to contract COVID-19."
Hayek said he hoped the research
would lead to a better understanding of the root links between heart
disease, inflammation and infectious diseases, perhaps to tease out
better markers that all the conditions might share.
"Because
there is an overlap between inflammation and cardiovascular disease,
understanding the link mechanistically will be of value not just for
this pandemic, but for any severe infectious illnesses to which patients
with heart disease are exposed," he said.
Editor's note:
Because of the rapidly evolving events surrounding the coronavirus, the
facts and advice presented in this story may have changed since
publication. Visit Heart.org for the latest coverage, and check with the
Centers for Disease Control and Prevention and local health officials
for the most recent guidance.
https://www.heart.org/en/news/2022/10/04/heart-risk-factors-not-heart-disease-itself-may-increase-odds-of-covid-19-death