General characteristics of study subjects.

Objectives
The purpose of this study is to investigate the impact of COVID-19 on admission and in-hospital mortality of patients with acute myocardial infarction (AMI).
Methods
We constructed a dataset of monthly hospitalizations and mortality of inpatients with AMI from January 2017 to December 2021 utilizing the National Health Insurance Claims Data which covers nearly the entire population. Using an interrupted time series (ITS), we investigated how COVID-19 affected hospitalizations and in-hospital deaths of patients with AMI.
Results
During the study period, the average age of patients with AMI was 65.2–65.8 years, and the ratio of men to women was higher, with 73.0–75.3% of patients being men and 24.7–27.0% being women. ITS analysis showed that admission rates of patients with AMI decreased one per 100,000 population due to COVID-19 (P<0.001). Reductions in admission rates were greatest among men, those aged 55 and older, and people with medical aid. COVID-19 did not affect inpatient mortality (p = 0.9608), but in-hospital mortality decreased from 12% to 7% in the medical aid group.
Conclusion
Overall, we found that COVID-19 had an impact on admission rates of patients with AMI but did not have a significant impact on in-hospital mortality. However, we also found differential impacts by sex, age, and socioeconomic status, indicating some may be more vulnerable. This highlights the importance of identifying and supporting these vulnerable populations to prevent poorer health outcomes.