Our study focused on comparing the impact of the COVID-19 pandemic on transfer status and mortality in STEMI patients. After propensity score matching and stratification by transfer status, no difference in mortality was found in STEMI patients in 2020 compared to those from 2016 to 2019. However, STEMI patients with concurrent COVID-19 infection in 2020 had higher odds of mortality across all three cohorts (regular admissions, acute care transfers and non-acute care transfers) than STEMI patients without COVID-19 from 2016 to 2019. STEMI patients in 2020 were also more likely to have acute hepatic failure, acute respiratory distress syndrome, atrial flutter, hypothyroidism, viral cardiomyopathy, severe sepsis, supraventricular tachycardia and ventricular tachycardia.

To our knowledge, our study is the largest study examining the impact of the COVID-19 pandemic on STEMI mortality while using STEMI patients between 2016 to 2019 as a baseline for comparison. A significant decrease in STEMI admissions was registered globally during the initial stages of the COVID-19 pandemic. Reasons for the declining incidence of STEMI include stay-at-home orders, a decrease in activities that could trigger STEMI and fear of contracting COVID-19.^13-15 Additionally, several studies in European countries observed that the pandemic was associated with a significantly longer ischemia time, including a longer door-to-balloon time and a significant reduction in the number of STEMI patient undergoing PCI.^16,17 Factors associated with delayed management include an increase in transportation time, the need for personal protection equipment and the increased burden on healthcare systems overall.¹⁷ As 2020 progressed, overall STEMI mortality decreased, which is why there is no significant difference in overall STEMI mortality in 2020 compared to STEMI mortality between 2016 to 2019.¹

Consistent with our findings, a study by Goel et al. also found that concurrent COVID-19 infection increases the odds of inpatient STEMI mortality.¹ Previous studies have demonstrated that COVID-19 infection raises the risk of acute myocardial infarction through various mechanisms, including a cytokine storm, hypercoagulability and endothelial dysfunction.^18-25 Although the specific factors contributing to inferior inpatient outcomes for STEMI patients with concurrent COVID-19 infection are not yet fully understood, it is speculated that these patients are more susceptible to associated cardiovascular complications and carry a higher thrombus burden.¹

Our study is also the first to examine the impact of concurrent COVID-19 infection on STEMI mortality stratified by transfer status. Regardless of transfer status, STEMI patients with concurrent COVID-19 faced higher mortality odds than those without COVID-19. Although hospitals often transfer only the sickest patients, the pronounced difference in mortality odds between acute and non-acute care transfer cohorts relative to the regular hospital admission cohort suggests that the lack of healthcare access, particularly in underserved regions, may also be a contributing factor. Approximately 60 million individuals reside in rural America. On average, they are older, have higher rates of chronic medical conditions than urban residents and rely on local hospitals for healthcare.^26-28 Unfortunately, since 2005, 161 rural hospitals have closed. As of February 2019, 673 rural hospitals were at risk of closing due to lower patient volumes, workforce shortages, inadequate reimbursements and costly medications.^29-31 Moreover, as of 2018, the United States had only 19.1 total hospitals per 1,000,000 population, significantly lower than the comparable country average of 32.7.³² The COVID-19 pandemic further exacerbated these issues, with more than 36 hospitals entering bankruptcy and 21 hospitals closing in 2020.^33,34 Additionally, nursing homes confronted with severe COVID-19 outbreaks in 2020 experienced significant reductions in nursing staff levels and struggled to recover the lost staff even after 16 weeks.³⁵ According to the Bureau of Labor Statistics, nursing homes have lost nearly 229,000 caregivers (14% of their workforce) since February 2020. These factors potentially contributed to delays in patient care, resulting in increased complications and mortality.³⁶

Another compounding factor for increased STEMI and COVID-19 mortality is the national physician shortage. The U.S. Census Bureau estimated an increase of 13,787,044 individuals in the 65-and-older population between 2010 and 2020.³⁷ In 2012, the Association of American Medical Colleges (AAMC) predicted that by 2020, the United States would have a shortage of 45,400 primary care physician and 46,100 medical specialists.^38,39 Unfortunately, the COVID-19 pandemic has exacerbated this issue by causing increased healthcare worker burnout, trauma and mental health issues.^40,41 Between the beginning of 2019 and the fall of 2021, 3272 physicians left the workforce. Since the start of the pandemic, 3500 healthcare workers have died, with 17% being physicians.^40-42 The American population is projected to grow from 328 million in 2019 to 363 million in 2034, with a 42.4% increase in individuals aged 65 and above.³⁸ During this period, the United States could experience an estimated physician shortage ranging from 37,800 to 124,000, further intensifying disparities in healthcare access.^38,42

STEMI patients with concurrent COVID-19 infection constitute a high-risk cohort with higher odds of facing inpatient mortality than STEMI patients without COVID-19. The national physician shortage and unequal distribution of healthcare resources may place many patients who lack appropriate healthcare access at increased risk for inpatient mortality. Further discussion and research should explore potential interventions to address these challenges, thereby better equipping our healthcare system to manage not only present issues but also future global health challenges.

Our study has limitations. The use of the NIS database introduces an inherent risk of miscoded diagnoses. Clinically relevant data, such as left ventricular ejection fraction, imaging results, medications administered, route of PCI access, number of stents placed, procedural details, outcomes after discharge, readmission rate and prior hospitalizations, were unavailable, potentially causing confounding and impacting the results. Of the 158,570 STEMI patients in 2020, 30,470 (19.2%) patients were included in the final analysis. Patient selection may change based on calculated propensity scores, introducing potential selection bias and affecting the generalizability of our findings. Lastly, the type of COVID-19 variant and the relationship between vaccination status and in-hospital outcomes could not be assessed.