Air pollution and ST-segment depression in elderly subjects.
Increased levels of daily ambient particle pollution have been associated with increased risk of cardiovascular morbidity. Black carbon (BC) is a measure of the traffic-related component of particles. We investigated associations between ambient pollution and ST-segment levels in a repeated-measures study including 269 observations on 24 active Boston residents 61-88 years of age, each observed up to 12 times from June through September 1999. The protocol involved continuous Holter electrocardiogram monitoring including 5 min of rest, 5 min of standing, 5 min of exercise outdoors, 5 min of recovery, and 20 cycles of paced breathing. Pollution-associated ST-depression was estimated for a 10th- to 90th-percentile change in BC. We calculated the average ST-segment level, referenced to the P-R isoelectric values, for each portion of the protocol. The mean BC level in the previous 12 hr, and the BC level 5 hr before testing, predicted ST-segment depression in most portions of the protocol, but the effect was strongest in the postexercise periods. During postexercise rest, an elevated BC level was associated with -0.1 mm ST-segment depression (p = 0.02 for 12-hr mean BC; p = 0.001 for 5-hr BC) in continuous models. Elevated BC also predicted increased risk of ST-segment depression > or = 0.5 mm among those with at least one episode of that level of ST-segment depression. Carbon monoxide was not a confounder of this association. ST-segment depression, possibly representing myocardial ischemia or inflammation, is associated with increased exposure to particles whose predominant source is traffic.
Channing Laboratory, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA. diane.gold@channing.harvard.edu
Diane R
DR
Gold
Augusto A
AA
Litonjua
Antonella
A
Zanobetti
Brent A
BA
Coull
Joel
J
Schwartz
Gail
G
MacCallum
Richard L
RL
Verrier
Bruce D
BD
Nearing
Marina J
MJ
Canner
Helen
H
Suh
Peter H
PH
Stone
D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis; D000397:Air Pollution / Q000009:adverse effects*; D002244:Carbon / Q000009:adverse effects* / Q000032:analysis; D002248:Carbon Monoxide / Q000009:adverse effects / Q000032:analysis; D004391:Dust / Q000032:analysis; D015716:Electrocardiography, Ambulatory; D004784:Environmental Monitoring; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D001335:Vehicle Emissions / Q000009:adverse effects*
D000393:Air Pollutants; D004391:Dust; D001335:Vehicle Emissions; D002244:Carbon; D002248:Carbon Monoxide