A national study suggests that risk factors for cardiovascular disease, such as age, smoking and diabetes – not pre-existing heart disease – are the main contributors to death and poor outcomes for critically ill COVID-19 patients.

A team led by Michigan Medicine researchers analyzed outcomes for more than 5,100 patients admitted to intensive care units at 68 centers across the United States with severe COVID between March and June of 2020. Of those patients, 1,174 had either pre-existing coronary artery disease, congestive heart failure or atrial fibrillation.

Results reveal that patients with cardiovascular disease had close to a 30% higher mortality rate than critically ill COVID patients without the pre-existing condition. However, when adjusting for risk factors – including age, sex, race, smoking and others – that relationship was no longer statistically significant. The findings are published in Circulation: Cardiovascular Quality and Outcomes.

SEE ALSO: Cardiac Arrest, Poor Survival Rates Common in Sickest Patients with COVID-19

"The fact that the association between cardiovascular disease and death was so heavily diminished when accounting for comorbidities suggests that cardiovascular risk factors rather than pre-existing heart disease are the main contributors to in-hospital death in patients with severe COVID-19," said senior author Salim Hayek, M.D., an assistant professor of internal medicine and medical director at the University of Michigan Health Frankel Cardiovascular Center Clinics.

A total of 34.6% of patients died within 28 days and nearly 18% suffered a cardiovascular event, such as cardiac arrest or myocarditis. Researchers say the association between such events and death did not differ between patients with and without preexisting heart disease.

Like Podcasts? Add the Michigan Medicine News Break on Spotify, Apple Podcasts or anywhere you listen to podcasts.

Cardiovascular disease is a common condition among patients who suffer severe COVID illness, given its prevalence among older adults and association with chronic inflammation. In the study, age, obesity and diabetes were much stronger predictors of death due to COVID.

Regardless of whether a patient had pre-existing heart disease, researchers found the presence of myocardial injury was associated with cardiovascular events and death. Myocardial injury was common among patients in the ICU, occurring in nearly half of patients who had heightened levels of troponin, a protein released when the heart muscle is damaged. Patients with the highest troponin measurements were nearly three times more likely to die than those without myocardial injury.

SEE ALSO: High blood sugar and suPAR levels independently worsen COVID-19 outcomes

"While patients with severe COVID commonly had signs of cardiac injury, our findings reinforce COVID-19 as a pulmonary disease with multi-organ injury related to systemic inflammation," Hayek said. "The evidence of heart damage that we frequently see in patients with severe COVID-19 is more likely a reflection of the severity of the illness and the stress it imparts on all organs rather than the development of new complications or the exacerbation of pre-existing heart disease."

The findings should not minimize the fact that patients with cardiovascular disease are still at risk for death due to COVID-19, as they have a high burden of risk factors for the disease, such as diabetes, hypertension and smoking, says co-first author Alexi Vasbinder, Ph.D., R.N., a postdoctoral fellow in internal medicine.

"We are currently working on studies to further define groups of patients with COVID-19 at highest risk for severe outcomes, such as those with advanced heart failure or coronary artery disease," Vasbinder said.

Live your healthiest life: Get tips from top experts weekly. Subscribe to the Michigan Health blog newsletter

Headlines from the frontlines: The power of scientific discovery harnessed and delivered to your inbox every week. Subscribe to the Michigan Health Lab blog newsletter

Additional authors include Chelsea Meloche, M.D., Tariq U. Azam, M.D., Elizabeth Anderson, M.S., Tonimarie Catalan, Husam Shadid, M.D., Hanna Berlin, Michael Pan, M.D., Patrick O'Hayer, M.D., Kishan Padalia, M.D., Pennelope Blakely, Ibrahim Khaleel, M.D., Erinleigh Michaud, M.D., Yiyuan Huang, Lili Zhao, Ph.D., Rodica Pop-Busui, M.D., Kim Eagle, M.D., all of University of Michigan, Shruti Gupta, M.D., David E. Leaf M.D., both of the Division of Renal Medicine at Brigham and Women's Hospital.

Vasbinder is supported by a National Heart, Lung, Blood Institute funded post-doctoral fellowship (T32HL007853). Dr. Leaf is supported by R01HL144566. Hayek is supported by 1R01HL153384 and the Frankel Cardiovascular Center COVID-19: Impact Research Ignitor (U-M G0242.

Paper cited: "Relationship Between Preexisting Cardiovascular Disease and Death and Cardiovascular Outcomes in Critically Ill Patients With COVID-19," Circulation: Cardiovascular Quality and Outcomes. DOI: 10.1161/CIRCOUTCOMES.122.00894