As the number of COVID-19 infection surged during the pandemic, deaths from heart attacks rose sharply as well, with adults ages 25-44 experiencing the most significant increases, according to new research from scientists at Cedars-Sinai Medical Center in Los Angeles.

“The dramatic rise in heart attacks during the pandemic has reversed what was a prior decadelong steady improvement in cardiac deaths,” said Dr. Yee Hui Yeo, first author of the study and a Cedars-Sinai physician-scientist. “We are still learning the many ways by which COVID-19 affects the body, regardless of age, gender, ethnicity or race.”

Scientists around the nation and world continue to release findings that show SARS-CoV-2 infections increase risk of other serious conditions such as stroke, nerve damage and some autoimmune diseases.

While other infections such as the flu are known to lead to a slightly increased risk of heart attacks, the Cedars-Sinai researchers said, they could find nothing that compared with the jump in deaths linked to the COVID-19 pandemic. Among their findings published in the peer-reviewed “Journal of Medical Virology:”

U.S. deaths attributed to heart attacks, or acute myocardial infarctions as they are medically known, shot up 14% to 164,096 in the first year of the pandemic, April 1, 2020, to Mar 31, 2021.

By the second year of the pandemic, the dramatic increases in heart attacks blew apart the models used to predict how many people would lose their lives to these events. Fatal heart attacks among adults ages 25-44 soared 29.9% over what was predicted. Deaths from heart attack climbed by 19.6% for adults ages 45-64 and by 13.7% for ages 65 and older.

These excessively higher rates of heart attack-related death have persisted throughout the pandemic, the Cedars-Sinai researchers found, including the possibility that COVID-19 could trigger or accelerate coronary artery disease. The scientists said more research has to be done to pinpoint risks.

“There is something very different about how this virus affects the cardiac risks,” said Dr. Susan Cheng, director of the Institute for Research on Healthy Aging in the Department of Cardiology at the Smidt Heart Institute and senior and co-corresponding author of the study. “The difference is likely due to a combination of stress and inflammation, arising from predisposing factors and the way this virus biologically interacts with the cardiovascular system.”

Certainly, Cheng and the other researchers said, behavioral health challenges associated with the pandemic — job losses, isolation, the unexpected deaths of relatives, or other pressures — can also cause acute or chronic stress leading to cardiac disease.

Because of this increased risk of stress, many Americans have fallen out of the habit of exercising and may have skipped medical check-ups that could detect problems, said a separate team of Cedars-Sinai researchers who reported in August that COVID-19 was linked to an increase risk of stroke.

Individuals who were vaccinated were 200 times less likely to have a stroke after having the respiratory disease. Those who had severe cases of COVID-19 were at a much greater risk of experiencing inflammation, blood clots and heart disease

Dr. Nancy Sicotte, chair of the Department of Neurology and the Women’s Guild Distinguished Chair in Neurology at Cedars-Sinai, strongly recommended vaccines for individuals in high-risk groups. This includes those who have lung or cardiovascular disease, high blood pressure, high cholesterol, diabetes, a prior stroke, people who are immunocompromised, and individuals aged 65 and older.