What is the clinical evidence from this study?

Study design: Observational. Population: Acute Coronary Syndrome (ACS) (n=3306). Intervention: Unvaccinated status (COVID-19) vs. COVID-19 Vaccination (Inactivated or mRNA). Primary outcome: Mortality (OR 3.77, 95% CI 1.04-13.65, p=0.043).

What question did this study set out to answer?

To examine the frequency of emergency department visits and mortality rates associated with acute coronary syndrome before and after the COVID-19 pandemic.

May 14, 2026Open Access

Relationship between acute coronary syndrome and coronavirus disease 2019 infection and vaccination type: a retrospective observational study

Key Result

Being unvaccinated against COVID-19 was associated with a 3.77-fold higher odds of mortality in patients presenting with acute coronary syndrome after the pandemic.

Key Points

To examine the frequency of emergency department visits and mortality rates associated with acute coronary syndrome before and after the COVID-19 pandemic.
Analyzed data from 1,856 post-pandemic and 1,450 pre-pandemic ACS patients.
Compared emergency visits and mortality rates, including demographics and lab results.
Investigated the association of vaccination status with post-pandemic mortality outcomes.
Emergency department visits nearly doubled post-pandemic; mortality rates remained similar (P=0.595).
Unvaccinated individuals exhibited 3.77-fold higher odds of mortality (95% CI: 1.04–13.65; p=0.043).
Cardiac marker levels significantly increased in post-pandemic patients compared to pre-pandemic patients.

Study Design

Type

Observational (n=3,306)

Multicenter

Structured PICO

Does the post-COVID-19 pandemic period or COVID-19 vaccination status affect mortality in patients with acute coronary syndrome?

Population

3,306 patients over the age of 18 diagnosed with acute coronary syndrome (STEMI, NSTEMI, and unstable angina pectoris), comprising 1,856 post-pandemic (2023) and 1,450 pre-pandemic (2018) patients.

Intervention

Post-pandemic period (2023) and COVID-19 vaccination status (unvaccinated, inactivated vaccine, mRNA vaccine)

Comparator

Pre-pandemic period (2018) and vaccinated status

Outcome

Frequency of emergency department visits and mortality rateshard clinical

While overall ACS mortality did not change post-pandemic, being unvaccinated against COVID-19 was associated with significantly higher mortality in post-pandemic ACS patients.

Main Result

Effect estimate: OR 3.77 (95% CI 1.04-13.65)

p-value: p=0.043

Limitations

Single-center study design limits external validity and generalizability
Retrospective design
Potential information bias due to erroneous entries in the electronic record system
Case selection bias because patients who had COVID-19 but were not tested were excluded
Socioeconomic status of patients could not be assessed
Potential differences in service utilization and demographics between the 2018 and 2023 cohorts

Abstract

Studies have reported that the Coronavirus Disease 2019 (COVID-19) vaccine causes other serious health problems, including myocarditis, pericarditis, neurological problems, and problems resulting from the reactivation of chronic infections. There are no satisfactory studies on the relationship between late-stage COVID-19 disease and cardiovascular diseases, or even Acute coronary syndrome (ACS). Our study primarily aimed to compare the frequency of emergency department (ED) visits and mortality rates of patients diagnosed with acute coronary syndrome (ACS) before and after the COVID-19 pandemic. Secondly, we aimed to evaluate differences in demographic and laboratory characteristics between pre-pandemic and post-pandemic ACS patients. Finally, we aimed to investigate the association between COVID-19 vaccination status (unvaccinated, inactivated vaccine, and mRNA vaccine) and mortality outcomes in post-pandemic ACS patients. Data from 1,856 patients over the age of 18 diagnosed with ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), and unstable angina pectoris (USAP) in 2023, post-pandemic, and 1,450 patients diagnosed in 2018, pre-pandemic, were analyzed. The incidence of ACS before and after the pandemic, its relationship with the presence of viral vector-based vaccination and mRNA vaccination, and demographic and laboratory results were retrospectively examined. Although the number of emergency department visits nearly doubled after the pandemic, mortality rates were similar (P = 0.595). Troponin I (P < 0.001), creatine kinase-MB (CK-MB) (P < 0.001), and prothrombin time (PT) (P = 0.016) levels were significantly increased in post-pandemic patients. Univariable analysis showed that being unvaccinated was associated with 2.88-fold higher odds of mortality (95% CI: 1.23–6.70), while in the multivariable analysis this association remained significant with 3.77-fold higher odds (95% CI: 1.04–13.65) (p = 0.014 and p = 0.043). Inactivated vaccine OR 0.60 (95% CI: 0.36–1.01) and p = 0.054 and mRNA vaccine OR 1.42 (95% CI: 0.85–2.36) and p = 0.177 did not have a significant effect on mortality. Post-pandemic mortality rates were similar to those before the pandemic. Being unvaccinated was found to be a significant associated with higher mortality. Vaccination type did not affect mortality. Cardiac and inflammatory marker levels were increased in post-pandemic ACS patients compared to pre-pandemic ACS patients.

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