Background: COVID-19 vaccination is thought to offer cardioprotective benefits, but little is known about how vaccination effects patients with myocardial infarction (MI), including those with concurrent COVID-19. Limited research has shown that in patients with COVID-19 and ST-Elevation MI (STEMI), COVID-19 vaccination was associated with reduced mortality, however, no evidence is available in patients with non-STEMI (NSTEMI). We aimed to assess the impact of COVID-19 vaccination on mortality in STEMI and NSTEMI patients.
METHODS AND RESULTS: Data sources were linked using unique encoded identifiers at individual level and analyzed within the Ontario Health Data Platform (OHDP), a secure data environment designed to support health research and system improvement during the COVID-19 pandemic. The Registered Persons Database was used to access demographic details, the Discharge Abstract Database for chronic conditions, and the National Ambulatory Care Reporting System for emergency department visits. Vaccination-related outcomes were obtained from the Ontario COVID-19 Vaccine Database and COVID-related outcomes from the Ontario Laboratories Information System. Primary exposure was vaccination status within 30 days prior to the MI. Dose number was classified as 0, 1-2, and ≥ 3 for doses received prior to the MI. Multivariable logistic regression was used to examine the association of vaccination for COVID-19 with all-cause mortality, adjusted for age, sex, vaccine dose number, hypertension, diabetes, left ventricular block, coronary stenosis, acute respiratory distress syndrome, pulmonary embolism, congestive heart failure, and cardiogenic shock.
54,774 patients presented with MI between 2020 and 2022, 19,268 (35%) with STEMI, and 35,506 (65%) with NSTEMI. Of these patients, 1,216 had COVID-19, 374 (31%) STEMI and 842 (69%) NSTEMI. Deaths occurred in 14% STEMI and 17% of NSTEMI patients. Of those with COVID-19 within 30-days, 19% with STEMI and 20% with NSTEMI died. 75% of STEMI and 65% of NSTEMI patients were vaccinated for COVID-19. In the non-vaccinated 67% with STEMI and 68% of NSTEMI died. Being vaccinated was associated with lower odds of mortality (OR = 0.78, 95% CI: 0.68, 0.88) with an increased number of vaccine doses providing greater reductions. A combination of different vaccine brands/types further lowered the odds of mortality (OR = 0.20 , 95% CI: 0.18, 0.23) in STEMI patients.
Conclusion: In a susceptible population of patients with COVID-19 and MI, having at least one vaccination is associated with improved survival, with further improvements based on having more vaccine doses. An unexpected finding is that having different brands of COVID-19 vaccinations appears to provide the most cardioprotective effects.
