Reduction in heart rate variability with traffic and air pollution in patients with coronary artery disease.
BACKGROUND
Ambient particulate pollution and traffic have been linked to myocardial infarction and cardiac death risk. Possible mechanisms include autonomic cardiac dysfunction.


METHODS
In a repeated-measures study of 46 patients 43-75 years of age, we investigated associations of central-site ambient particulate pollution, including black carbon (BC) (a marker for regional and local traffic), and report of traffic exposure with changes in half-hourly averaged heart rate variability (HRV), a marker of autonomic function measured by 24-hr Holter electrocardiogram monitoring. Each patient was observed up to four times within 1 year after a percutaneous intervention for myocardial infarction, acute coronary syndrome without infarction, or stable coronary artery disease (4,955 half-hour observations). For each half-hour period, diary data defined whether the patient was home or not home, or in traffic.


RESULTS
A decrease in high frequency (HF; an HRV marker of vagal tone) of 16.4% [95% confidence interval (CI), 20.7 to 11.8%] was associated with an interquartile range of 0.3-microg/m3 increase in prior 5-day averaged ambient BC. Decreases in HF were independently associated both with the previous 2-hr averaged BC (10.4%; 95% CI, 15.4 to 5.2%) and with being in traffic in the previous 2 hr (38.5%; 95% CI, 57.4 to 11.1%). We also observed independent responses for particulate air matter with aerodynamic diameter < or = 2.5 microm and for gases (ozone or nitrogen dioxide).


CONCLUSIONS
After hospitalization for coronary artery disease, both particulate pollution and being in traffic, a marker of stress and pollution, were associated with decreased HRV.
Zanobetti
Antonella
A
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02215, USA. azanobet@hsph.harvard.edu
Gold
Diane R
DR
Stone
Peter H
PH
Suh
Helen H
HH
Schwartz
Joel
J
Coull
Brent A
BA
Speizer
Frank E
FE
D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000633:toxicity*; D001900:Boston; D002244:Carbon / Q000633:toxicity; D003324:Coronary Artery Disease / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018986:Motor Vehicles; D009203:Myocardial Infarction / Q000503:physiopathology; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D013997:Time Factors
D000393:Air Pollutants; D052638:Particulate Matter; D002244:Carbon