Declining Myocarditis Mortality in the United States and the Impact of the COVID-19 Pandemic

Background: Myocarditis is associated with increased mortality due to complications such as cardiogenic shock and arrhythmia. Trends of myocarditis-related mortality in the United States, along with demographic and regional disparities and changes during the COVID-19 pandemic, are unknown. Methods: We used the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER) database to extract data for myocarditis deaths from 1999 to 2023. The Joinpoint Regression Program was used to analyze long-term trends in mortality, and R Studio (version 4.4.1) was used to calculate expected and excess mortality for 2020 to 2023. Results: There were 33,016 myocarditis-related deaths from 1999 to 2023. The age-adjusted mortality rate (AAMR) of myocarditis deaths decreased by 46.08% from 7.40 (95% CI: 7.04-7.76) in 1999 to 3.99 (95% CI: 3.74-4.23) in 2019, with an APC of -2.59 (95% CI: -2.97 to -2.24). From 2019 to 2021, the AAMR increased by 46.62% to 5.85 (95% CI: 5.56-6.14) by 2021 (2019-2021 APC 22.3%*), reversing the gains of the previous two decades. By 2023, the AAMR recovered to 4.33 (95% CI: 4.09 to 4.58), though mortality was still higher than expected from pre-pandemic trends. From 2020 to 2023, there were 40.12% more deaths than expected, with 54.94% higher mortality in 2021. Briefly, 70.33% of excess myocarditis-related deaths also had COVID-19, with a peak of 76.15% of excess myocarditis deaths in 2021 being reported as involving COVID-19 infection. Significant disparities in mortality trends persisted, with males, NH Black or African Americans, and the elderly having higher mortality rates. Conclusions: Myocarditis mortality decreased in the United States from 1999 to 2019 but significantly increased during the COVID-19 pandemic years 2020 and 2021. At the height of the pandemic, COVID-19 infection contributed to almost three-quarters of excess myocarditis mortality. Significant disparities in myocarditis mortality persisted from 1999 to 2023.