Particulate Air Pollution and Risk of ST-Segment Depression During Repeated Submaximal Exercise Tests Among Subjects With Coronary Heart Disease

Abstract

Background-Daily variations in ambient particulate air pollution have been associated with cardiovascular mortality and morbidity. We therefore assessed the associations between levels of the 3 main modes of urban aerosol distribution and the occurrence of ST-segment depressions during repeated exercise tests. Methods and Results-Repeated biweekly submaximal exercise tests were performed during 6 months among adult subjects with stable coronary heart disease in Helsinki, Finland. Seventy-two exercise-induced ST-segment depressions Ͼ0.1 mV occurred during 342 exercise tests among 45 subjects. Simultaneously, particle mass Ͻ2.5 m (PM2.5) and the number concentrations of ultrafine particles (particle diameter 10 to 100 nm [NC 0.01-0.1 ]) and accumulation mode particles (100 to 1000 nm [NC 0.1-1 ]) were monitored at a central site. Levels of particulate air pollution 2 days before the clinic visit were significantly associated with increased risk of ST-segment depression during exercise test. The association was most consistent for measures of particles reflecting accumulation mode particles (odds ratio 3.29; 95% CI, 1.57 to 6.92 for NC 0.1-1 and 2.84; 95% CI, 1.42 to 5.66 for PM2.5), but ultrafine particles also had an effect (odds ratio 3.14; 95% CI, 1.56 to 6.32), which was independent of PM2.5. Also, gaseous pollutants NO 2 and CO were associated with an increased risk for ST-segment depressions. No consistent association was observed for coarse particles. The associations tended to be stronger among subjects who did not use ␤-blockers. Conclusions-The present results suggest that the effect of particulate air pollution on cardiovascular morbidity is at least partly mediated through increased susceptibility to myocardial ischemia. (Circulation. 2002;106:933-938.)

Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material

“…Numerous studies have shown that the concentration of inhalable particles (PM 10 ) in ambient air is associated with mortality and different kinds of respiratory health problems in the population (Katsouyanni et al, 2001, Peters et al, 2001, Brunekreef and Holgate, 2002, Pekkanen et al, 2002, Pope et al, 2002, Kappos, et al, 2004. Particle size seems to be important since smaller fractions tend to have stronger relationships to health effects (Schlesinger et al, 2006).…”

Air Pollution

“…Whereas this study by Pekkanen and colleagues 19 indicated an important association between particulate air pollution and exercise-induced myocardial ischemia, it has left unanswered several questions. Although the original protocol was designed to evaluate patients in 3 cities, the final report included data from 45 subjects evaluated in a single city over a 6-month time frame.…”

“…In the present issue of Circulation, Pekkanen and colleagues 19 present the results of the Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air (ULTRA) study. In this investigation, the authors followed a cohort of patients with established coronary heart disease with biweekly submaximal exercise tests over a 6-month period.…”

“…Because ischemia during outpatient daily activities occurs at lower heart rates than during a supervised exercise test, it would also be important to know whether episodes of myocardial ischemia were recorded with ambulatory ECG (Holter) monitors during routine daily activities in these patients. It may be possible that the cardiac risk identified by Pekkanen et al 19 during the exercise tests represents only a small amount of the actual ischemic risk that these patients encounter throughout the day. Variations of the ischemic threshold at different times would imply that air pollution is adversely affecting the coronary endothelium and leading to different degrees of vasoconstriction.…”

“…As is the case for any novel investigation, the study by Pekkanen and coworkers 19 raises more questions than it answers. Foremost among the questions to be addressed is the identification of the specific particles responsible, including their size, composition, and origin, as differential effects based on these characteristics would be anticipated.…”