Cumulative exposure to particulate matter air pollution and long-term post-myocardial infarction outcomes

• Median follow-up of 19 years for total mortality and 13 years for cardiac death and recurrent events
• Clinical data were collected from multiple sources and ascertained by a senior cardiologist.
• Adjustment was conducted for neighborhood SES in addition to personal risk factors.
• Employment, smoking, diabetes and physical activity were treated as time-dependent variables.
• Chronic exposure to PM2.5 was associated with cardiovascular events after a first MI.

IntroductionChronic environmental exposure to particulate matter < 2.5 μm in diameter (PM2.5) has been associated with cardiovascular disease; however, the effect of air pollution on myocardial infarction (MI) survivors is not clear. We studied the association of chronic exposure to PM2.5 with death and recurrent cardiovascular events in MI survivors.MethodsConsecutive patients aged ≤ 65 years admitted to all medical centers in central Israel after first-MI in 1992–1993 were followed through 2005 for cardiovascular events and 2011 for survival. Data on sociodemographic and prognostic factors were collected at baseline and during follow-up. Residential exposure to PM2.5 was estimated for each patient based on data recorded at air quality monitoring stations. Cox and Andersen–Gill proportional hazards models were used to study the pollution-outcome association.ResultsAmong the 1120 patients, 469 (41.9%) died and 541 (48.3%) experienced one or more recurrent cardiovascular event. The adjusted hazard ratios associated with a 10 μg/m3 increase in PM2.5 exposure were 1.3 (95% CI 0.8–2.1) for death and 1.5 (95% CI 1.1–1.9) for multiple recurrences of cardiovascular events (MI, heart failure and stroke).ConclusionWhen adjustment for socio-demographic factors is performed, cumulative chronic exposure to PM2.5 is positively associated with recurrence of cardiovascular events in patients after a first MI.