Air pollution before and during the COVID-19 pandemic: changes in risk of acute myocardial infarction

Area of Science:

• Environmental Health Sciences
• Cardiovascular Research
• Epidemiology

Background:

• Ambient fine particulate matter (PM2.5) exposure is a recognized risk factor for acute myocardial infarction (AMI).
• Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a distinct AMI subtype compared to myocardial infarction with obstructive coronary disease (MI-CAD).
• The COVID-19 pandemic and associated public health interventions created a unique scenario to study environmental exposure impacts on cardiovascular events.

Purpose of the Study:

• To investigate the association between short-term PM2.5 exposure and AMI subtypes.
• To examine how this association changed before and after the COVID-19 pandemic onset.
• To assess potential impacts of pandemic-related public health measures on PM2.5 exposure and cardiovascular risk.

Main Methods:

• Utilized the nationwide JROAD-DPC database, analyzing 270,091 first-admission AMI patients (including 23,037 MINOCA) from April 2012 to March 2022.
• Employed a time-stratified case-crossover design with conditional logistic regression to estimate odds ratios (OR) for PM2.5 exposure at a 2-day lag.
• Divided the study period into pre-pandemic and post-pandemic phases, using April 7, 2020, as the threshold, and conducted sensitivity analyses with alternative dates.

Main Results:

• A significant association was found between each 10-μg/m³ increase in lag-2 PM2.5 exposure and increased AMI risk.
• While the PM2.5-AMI association remained stable for overall AMI and MI-CAD, a significant attenuation was observed for MINOCA risk post-pandemic (P for interaction = 0.017).
• Pre-pandemic OR for MINOCA was 1.303 (95% CI: 1.005-1.688), decreasing to 1.230 (95% CI: .973-1.555) post-pandemic, confirmed by sensitivity analyses.

Conclusions:

• Short-term PM2.5 exposure is consistently linked to elevated AMI risk.
• The observed reduction in MINOCA risk post-COVID-19 pandemic suggests public health interventions reducing air pollution exposure can mitigate cardiovascular risks.
• These findings highlight the potential for targeted interventions to protect vulnerable populations from specific cardiovascular events like MINOCA.