Many major cities had unprecedented increases in out-of-hospital cardiac arrests, or OHCA, in early 2020. A new international study has tied those and subsequent spikes to COVID-19, including in the United States.

These unusual increases in out-of-hospital cardiac arrest paralleled upticks in COVID-19 cases, investigators found. Incidence then fell in those same cities when pandemic mitigation measures were implemented, reported author Michael T. Osterholm, Ph.D., MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, or CIDRAP.

The findings suggest that OHCA is either an early symptom or complication of COVID-19 infection, the researchers concluded. What’s more, sudden surges of these heart attacks may be as an early signal of COVID-19 surges in a community, they said.

One month of rising COVID — and cardiac arrests 

In April 2020, when COVID cases began their sharp rise, 34 U.S. cities had greater than 20% increases in these out-of-hospital cardiac events when compared with April 2018 and April 2019. A one-and-a-half-fold increase occurred across 13 metropolitan areas. And three cities that were known COVID-19 epicenters (such as New York City) had greater than 100% increases. On average, U.S. out-of-hospital cardiac arrest rose 59% during that month. 

Cities with fewer COVID-19 cases, meanwhile, had unchanged or lessened numbers of out-of-hospital heart attacks, Osterholm and colleagues found.

Once mitigation measures kicked in, the cities with the highest out-of-hospital heart attack numbers returned to their pre-COVID-19 levels. But cities that were minimally affected by these trends in April saw their heart attack numbers escalate when COVID-19 began to surge locally, the researchers reported. Other countries had similar experiences in their large metro areas.

“What this is is one more reason why you don’t want to get this virus,” Osterholm said in an interview. “And over time, we’re going to uncover more and more of the collateral aspects of COVID-19 that are currently unappreciated.”

The study was published April 7 in EClinicalMedicine, an online publication from The Lancet.