There have been rumblings across the interventional cardiology world at how quiet the catheterization labs have become during the COVID-19 pandemic. But now the first confirmatory data from the U.S. is in, and it's astounding.

A model looking at activations for ST-segment elevation myocardial infarction (STEMI) showed a drop of 38% (95% CI 26-49) from roughly the year prior to the outbreak to the first month of it.

Across the nine high-volume centers dotted across the U.S. that pooled their data, the total STEMI activations went from more than 180 every month (mean 23.6 per center) to only 138 activations (mean 15.3).

These findings are similar to the 40% reduction noted in Spain, reported Santiago Garcia, MD, of the Minneapolis Heart Institute at Abbott Northwestern Hospital, and colleagues in the Journal of the American College of Cardiology.

The reduction in cath lab activity has also been widely noted anecdotally on Twitter.

There should actually have been an increase in STEMI activations, the researchers noted, given the extra stress people are under and the fact that viral illnesses, like the flu, can induce STEMI. Also, mimickers, such as COVID-19 myopericarditis, would be expected to boost STEMI activations, despite the deliberate reduction in elective cases.

"This absolutely confirms what we have been seeing in the New York area," commented Ajay Kirtane, MD, SM, director of the cardiac catheterization laboratories at Columbia University Irving Medical Center/NewYork-Presbyterian Hospital in New York City.

"The challenge is understanding why this is occurring, but my best estimate is that it is multifactorial," he told MedPage Today. "On the patient side, one could posit that perhaps more sedentary behavior, combined with smoking reductions, could lead to a reduced incidence of MI. On the other hand, in patients actually having MI, a strong desire to avoid coming to the hospital in conjunction with accessibility and diagnostic challenges (due to stressed and surging EMS [emergency medical services] and [ED emergency department] services) could also lead to this reduction in STEMI activations."

Whatever the reason, Garcia's group said that they plan to continue following this early signal as the pandemic unfurls. "It is particularly crucial to understand if patient-based anxiety is decreasing presentation of STEMI patients to the U.S. hospital system."

The American Heart Association has announced it will use its "Get With The Guidelines" registry to look at cardiovascular aspects of COVID-19. The Society for Cardiovascular Interventions and Angiography, and its Canadian counterpart, have started the North American COVID-19 ST-Segment Elevation Myocardial Infarction Registry.

Garcia and colleagues' study included nine high-volume cardiac catheterization laboratories (>100 primary PCIs per year): Minneapolis Heart Institute; Beaumont Hospital Royal Oak in Michigan; the Christ Hospital in Cincinnati; Massachusetts General Hospital in Boston; UMass Memorial Medical Center in Worcester; Iowa Heart in Des Moines; Northwell Health Hospital in Manhasset, New York; Prairie Cardiovascular in Springfield, Illinois; and Swedish Medical Center in Seattle.

The study period was Jan. 1, 2019 to March 31, 2020, with March 1, 2020 (the first day New York reported a case) as the starting point for the U.S. COVID-19 period.