Study Shows Myocarditis Caused by COVID-19 is Rare, Despite Previous Research

New research shows myocarditis is less common among COVID-19 patients than previously reported.

Myocarditis caused by coronavirus disease 2019 (COVID-19) may be less common than previous research suggests, according to a new study published in Cardiovascular Pathology.

Previous reports of the rate of COVID-19 myocarditis have ranged from 60% among middle-aged and elderly recovered patients to 14% among recovered athletes, according to study authors.

“Although it is clear that COVID-19 impacts the heart and blood vessels, to date, it has been difficult to know how reproducible any changes are due to the relatively small sample size of most autopsy series,” said co-author Richard Vander Heide, MD, PhD, professor, director, pathology research, LSU Health New Orleans School of Medicine, Louisiana, in a press release.

Heide and colleagues reviewed data from 22 different studies to analyze findings related to the autopsied hearts of 277 patients who died from COVID-19. Patients were from 9 different countries, the average patient age was 75-years-old, and 97.6% of patients had at least 1 comorbidity.

After careful review, the researchers found that the rate of myocarditis ranged between 1.4% and 7.2% among study participants.

“What we have learned is that myocarditis is not nearly as frequent in COVID-19 as has been thought,” said co-author Marc Halushka, MD, PhD, professor of pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, in the same press release. “This finding should be useful for our clinical colleagues to reconsider how to interpret blood tests and heart radiology studies.”

“By bringing the data together from this large number of autopsy cases, we have better determined the spectrum of histologic findings,” added Vander Heide in the press release. “Even a low myocarditis rate of 1.4% would predict hundreds of thousands of worldwide cases of myocarditis in severe COVID-19 due to the enormous numbers of infected individuals.”

Also, the study authors created a “checklist” for pathologists to use when evaluating COVID-19 at autopsy in order to provide consistency in investigating and reporting results.

“This study demonstrates the importance of the autopsy in helping us determine what is occurring in the hearts of individuals passing away due to COVID-19,” concluded Halushka in the press release.