By By American Heart Association News HealthDay Reporter, HealthDay Reporter
TUESDAY, Oct. 4, 2022 (American Heart Association News) — 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.