The COVID-19 Pandemic and Associated Inequities in Acute Myocardial Infarction Treatment and Outcomes

The COVID-19 pandemic significantly stressed the US healthcare system, leading to disruptions in usual care, particularly for urgent conditions like AMI. Previous research suggested excess mortality from causes other than COVID-19 during the pandemic, disproportionately affecting racial and ethnic minorities. Black and Hispanic individuals experienced higher COVID-19 death rates than White individuals. This study aimed to determine if the pandemic was associated with increased disparities in AMI treatment and outcomes among Medicare patients. Specifically, it questioned whether AMI patients experienced different rates of revascularization, mortality, readmission, or non-home discharges in hospitals with high versus low COVID-19 burdens, and whether these differences were more pronounced in Black and Hispanic individuals compared to White individuals. The findings are crucial for informing strategies to create a more equitable healthcare system and improve cardiovascular care during future pandemics.

Prior studies indicated significant excess mortality from causes other than COVID-19 during the pandemic, including cardiovascular disease. These excess deaths were more pronounced among minority groups. Some studies showed higher mortality rates after emergency surgery in hospitals with high COVID-19 caseloads, but these disparities were not consistent across racial and ethnic groups. While previous research reported increased AMI mortality during the pandemic, it remained unclear if this increase disproportionately affected racial and ethnic minorities. This study builds upon this existing literature by using a large national dataset to assess the impact of COVID-19 hospital burden on AMI outcomes across racial and ethnic groups.

This cross-sectional study used data from 1,512,924 Medicare patients (Hispanic, Black, and White) aged 65 and older hospitalized with NSTEMI or STEMI between January 1, 2016, and December 31, 2020. Patient-level data were merged with CMS Impact Files containing hospital characteristics. The study population, after exclusions, comprised 1,319,273 observations (1,022,430 NSTEMI and 296,834 STEMI admissions) across 3078 hospitals. The primary analysis used interrupted time-series models to assess the association between hospital COVID-19 burden (categorized into quintiles) and AMI outcomes (revascularization, 30-day mortality, readmission, non-home discharge). Unadjusted analyses were presented as primary findings to avoid underestimating disparities potentially masked by adjusting for pre-existing health differences. Post-hoc analyses examined changes in AMI admission volume and severity (STEMI vs. NSTEMI) and mortality rates during the early and later phases of the pandemic. Negative binomial regression and expanded mortality models were used in the post-hoc analyses. All analyses accounted for clustering within hospitals using robust variance estimators, with significance set at P < .05. A conservative approach was adopted, avoiding adjustment for multiple comparisons to minimize the risk of type II error.

Patients with NSTEMI admitted to hospitals during weeks with high COVID-19 burdens were less likely to undergo revascularization and more likely to experience 30-day mortality, readmission, and non-home discharge compared to those admitted during weeks with low burdens. Specifically, for NSTEMI patients, the adjusted odds of mortality increased by 10%, readmission by 21%, and non-home discharge by 51% in hospitals with COVID-19 burdens greater than 30%. In contrast, among STEMI patients, these increases were not statistically significant except for a possible increase in mortality at burdens greater than 30%. Importantly, the study found no substantial evidence of increased racial or ethnic disparities in mortality, revascularization, readmissions, or non-home discharges during the pandemic, even in hospitals with high COVID-19 burdens. However, pre-existing disparities persisted: Black and Hispanic individuals had significantly lower odds of revascularization compared to White individuals both before and during the pandemic (35-45% lower odds). Post-hoc analyses revealed a 5.2% reduction in weekly AMI admissions during the pandemic, with a more substantial decrease in NSTEMI admissions compared to STEMI admissions. There was no significant evidence of increased 30-day mortality during the pandemic, regardless of hospital COVID-19 burden or the phase of the pandemic (early vs. late).

The findings that high COVID-19 hospital burdens were associated with worse AMI outcomes, particularly for NSTEMI patients, align with previous research showing increased mortality in patients undergoing major surgery and increased AMI mortality during the pandemic. The lower revascularization rate for NSTEMI during the pandemic may reflect a reduction in non-essential procedures. The lack of increased disparities during the pandemic may be due to similar decreases in cardiac procedures across racial groups early in the pandemic. However, the persistent significant disparity in revascularization rates before and during the pandemic underscores the ongoing inequities in cardiovascular care. These inequities cannot be solely attributed to patient preferences, suggesting the influence of structural and individual racism. The early pandemic was associated with reduced AMI admissions, possibly reflecting reduced access to care or patient hesitancy. The lack of increased mortality during the pandemic is potentially due to improved management of COVID-19 and AMI.

This study of over 1.3 million AMI hospitalizations demonstrates that high COVID-19 hospital burdens were associated with reduced revascularization and increased adverse outcomes for AMI patients, especially those with NSTEMI. While the pandemic did not exacerbate existing racial and ethnic disparities, significant pre-existing inequities in revascularization persisted. These findings highlight the need for policy and clinical interventions to ensure equitable, high-quality care for all patients, even during periods of healthcare system stress. Future research should investigate the long-term consequences of AMI during the pandemic and explore interventions to address persistent racial and ethnic disparities in cardiovascular care.

This study's limitations include its reliance on Medicare data (excluding younger populations and potentially under-representing Medicare Advantage patients), the use of a proxy measure for hospital COVID-19 burden, and the inability to account for disparities in AMI prevalence or death before hospital admission. The observational nature of the study prevents causal inferences. The findings may not be generalizable to populations outside of the Medicare-eligible age group.