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

Introduction: Chronic environmental exposure to particulate matter 2.5) 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 PM_2.5 with death and recurrent cardiovascular events in MI survivors. Methods: Consecutive patients aged ≤65years 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 PM_2.5 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. Results: Among 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 10μg/m³ increase in PM_2.5 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). Conclusion: When adjustment for socio-demographic factors is performed, cumulative chronic exposure to PM_2.5 is positively associated with recurrence of cardiovascular events in patients after a first MI.