PROJECT SUMMARY/ABSTRACT:
Acute myocardial infarction (AMI), a major cause of cardiovascular disability and death in the US, can be
triggered by environmental exposures like heat, cold, and fine particulate air pollution (PM2.5). However, less is
known about whether temperature variability, elevated temperature-humidity metrics, or ground-level ozone
exposures could also trigger AMI, especially in young (aged 18-55 years) and older (aged ≥75 years) adults.
These exposures take on increasing importance in the context of climate change. Moreover, it remains unclear
whether women, persons of low socioeconomic status (SES), people with pre-existing chronic conditions, or
users of certain medications have elevated vulnerability to heat-related AMI risk. Furthermore, evidence
regarding whether co-exposures to extreme heat and air pollution interactively trigger AMI remains largely
lacking. The overall objectives in this application are to (i) evaluate the effects of extreme heat and air pollution
on AMI; and (ii) identify potential effect modification by sex, SES, medical history, and air pollution on the
association between exposure to extreme heat and AMI risk. To achieve these objectives, we will use two unique
US nationwide multicenter prospective observational cohort studies: VIRGO (Variation in Recovery: Role of
Gender on Outcomes of Young AMI Patients) and SILVER-AMI (Comprehensive Evaluation of Risk Factors in
Older Patients With Acute Myocardial Infarction). We will link patient-level medical record and interview data with
highly spatiotemporally resolved estimates of ambient air temperature and air pollution predicted from satellite-
based ensemble models and apply time-stratified case-crossover designs coupled with state-of-the-art
distributed lag nonlinear models. Specifically, we aim to: (1) assess the association of AMI occurrence with short-
term exposure to extreme heat, heat waves, temperature variability (both within and between days), and
temperature-humidity metrics (i.e., heat index, humidex, and wet bulb temperature) and examine its sex and
socioeconomic disparities; (2) determine whether medical history (pre-existing chronic conditions and medication
use) modifies the association between extreme heat and risk of AMI occurrence; and (3) estimate the association
of short-term co-exposure to extreme heat and air pollution (PM2.5 or ozone) with risk of AMI occurrence. The
proposed research is significant because it is expected to provide strong and actionable scientific evidence on
the roles of exposure to extreme heat and air pollution in AMI risk and on the roles of sex, SES, pre-existing
conditions, medication intake, and air pollution in contributing to population vulnerability to heat-related AMI, thus
greatly aiding clinicians, policymakers, and stakeholders to more effectively prevent adverse impacts of extreme
heat and air pollution in relation to AMI risk, especially under a warming climate.
