The number of myocardial infarctions declined during the early COVID-19 pandemic but mechanisms behind these declines are poorly understood. COVID-19 infection is also associated with an increased risk of myocardial infarction which could lead to higher incidence rates in the population. This study aims to shed light on the seemingly paradoxical relationship between COVID-19 and myocardial infarction occurrence on the population level by exploring long-term trends in incidence rates, case fatality, and proportion of patients dying before reaching a hospital. Our work is based on a linkage of administrative registers covering the entire population aged 60 + in Sweden. Considering both long-term trends since 2015 and seasonal variability, we compared observed incidence, case fatality, and proportions of patients hospitalized to expected values during 2020–2022. Despite more than 200 laboratory-confirmed COVID-19 cases per 1000 inhabitants by the end of 2022, incidence rates of myocardial infarction continued to decline, thus following the long-term trend observed already before 2020. During the first pandemic wave there was an additional incidence decline corresponding to 13% fewer myocardial infarctions than expected. This decline was neither accompanied by increasing case fatality nor by lower shares of patients being hospitalized. We found no increase in the population-level incidence of myocardial infarction despite large-scale exposure to COVID-19, which suggests that the effect of COVID-19 on myocardial infarction risk is not substantial. Increased pressure on the Swedish health care system has not led to increased risks or poorer outcomes for patients presenting with acute myocardial infarction.

在 COVID-19 大流行早期，心肌梗塞的数量有所下降，但人们对这些下降背后的机制知之甚少。 COVID-19 感染还与心肌梗塞风险增加相关，这可能导致人群发病率升高。本研究旨在通过探索发病率、病死率和到达医院前死亡的患者比例的长期趋势，阐明人口层面上的 COVID-19 与心肌梗死发生之间看似矛盾的关系。我们的工作基于覆盖瑞典所有 60 岁以上人口的行政登记册的链接。考虑到 2015 年以来的长期趋势和季节性变化，我们将 2020-2022 年观察到的发病率、病死率和住院患者比例与预期值进行了比较。尽管到 2022 年底，每 1000 名居民中有 200 多例实验室确诊的 COVID-19 病例，但心肌梗塞的发病率继续下降，从而遵循 2020 年之前观察到的长期趋势。在第一波大流行期间，出现了额外的发病率下降相当于心肌梗死比预期减少 13%。这种下降既没有伴随着病死率的增加，也没有伴随着住院患者比例的下降。我们发现，尽管大规模暴露于 COVID-19，但人群中心肌梗死的发病率并未增加，这表明 COVID-19 对心肌梗死风险的影响并不显着。瑞典医疗保健系统压力的增加并未导致急性心肌梗死患者的风险增加或预后较差。