Hospitalization Due to Acute Coronary Syndrome and Myocarditis in Patients Under 45 Years Old: A Single-Center Coronary Care Unit Retrospective Analysis of Hospitalizations Before, During, and After the Coronavirus Disease 2019 Pandemic.

Objective: Whether Coronavirus Disease 2019 (COVID-19) infection and vaccination contribute to the development of acute coronary syndrome (ACS) or myocarditis, particularly in young adults, remains controversial. This study aimed to evaluate the hospitalization rates for ACS and myocarditis in patients under 45 years of age during the pre-pandemic, pandemic, and post-pandemic periods.

Method: This retrospective, single-center study included 944 patients under the age of 45 who were admitted to the coronary care unit with a diagnosis of ACS or myocarditis. Patients were categorized into three groups based on admission periods: pre-pandemic (January 2019 to March 31, 2020), pandemic (April 1, 2020 to September 30, 2022), and post-pandemic (October 1, 2022 to December 31, 2023).

Results: There were no significant differences in the proportion of patients under 45 years old among total coronary care unit admissions across the three periods (12.9% vs 11.0% vs. 11.8%, respectively; P = 0.134). Similarly, although a slight increase was observed in the proportion of myocarditis cases relative to ACS over time, the difference was not statistically significant (29.9% vs. 70.1%, 32.0% vs. 68.0%, and 34.2% vs. 65.8%, respectively; P = 0.600). The rate of myocarditis was comparable between vaccinated and unvaccinated patients, with no significant differences based on vaccine types.

Conclusion: Hospitalization rates for ACS and myocarditis among patients under 45 years of age at our center were similar across the pre-pandemic, pandemic, and post-pandemic periods. These findings support previous studies suggesting no association between COVID-19 infection or vaccination and the occurrence of ACS or myocarditis. However, as a single-center retrospective study, our findings are limited to hospitalized cases and do not provide data on the overall incidence, prevalence, or causal relationships between these conditions and the pandemic.