Interplay between climate, pollution and COVID-19 on ST-elevation myocardial infarction in a large metropolitan region.

BACKGROUND: Collective risk factors such as climate and pollution impact on the risk of acute cardiovascular events, including ST-elevation myocardial infarction (STEMI). There is limited data however on the precise temporal and independent association between these factors and STEMI, and the potentially interacting role of government policies against Coronavrus Disease 2019 (COVID-19), especially for Latin America. METHODS: We retrospectively collected aggregate data on daily STEMI admissions at 10 tertiary care centers in the Buenos Aires metropolitan area, Argentina, from January 1, 2017 to November 30, 2020. Daily measurements for temperature, humidity, atmospheric pressure, wind direction, wind speed, and rainfall, as well as carbon monoxide (CO), nitrogen dioxide, and particulate matter <10 µm (PM10), were retrieved. Exploratory analyses focused on key COVID-19-related periods (eg first case, first lockdown), and stringency index quantifying the intensity of government policy response against COVID-19. RESULTS: A total of 1498 STEMI occurred over 1430 days, for an average of 0.12 STEMI per center (decreasing from 0.130 in 2018 to 0.102 in 2020, p=0.016). Time series analysis showed that lower temperature and higher concentration of CO and PM10 were all significantly associated with an increased rate of STEMI (all p<0.05), whereas COVID-19 outbreak, lockdown, and stringency of government policies were all inversely associated with STEMI (all p<0.05). Notably, environmental features impacted as early as 28 days before the event (all p<0.05), even if same or prior day associations proved stronger (all p<0.05). Multivariable analysis suggested that maximum temperature (p=0.001) and PM10 (p=0.033) were the strongest predictor of STEMI, even after accounting for COVID-19-related countermeasures (p=0.043). CONCLUSIONS: Lower temperature and higher concentrations of CO and PM10 are associated with significant increases in the rate of STEMI in a large Latin American metropolitan area. The reduction in STEMI cases seen during the COVID-19 pandemic is at least in part mediated by improvements in pollution, especially reductions in PM10.