Reduces ST-segment Depression on Electrocardiograms
John McCracken, Kirk R. Smith, Peter Stone, Anaité Díaz, Byron Arana, Joel Schwartz
http://www.ncbi.nlm.nih.gov/pmc/?term=1 ... hp.1002834
Background: A large body of evidence suggests that fine particulate air pollution is a cause of cardiovascular disease, but little is known in particular about the cardiovascular effects of indoor air pollution from household use of solid fuels in developing countries. RESPIRE was a randomized trial of a chimney woodstove that reduces woodsmoke exposure.
Objectives: Test the hypotheses that the stove intervention, as compared to open fire use, would reduce ST-segment depression and increase heart rate variability (HRV).
Methods: We used two complementary study designs: (a) between-groups comparisons based on randomized stove assignment, and (b) before-and-after comparisons within control subjects, who used open fires during the trial and received chimney stoves after the trial. Electrocardiogram sessions lasting 20 hours were repeated up to three times among 49 intervention and 70 control women 38 to 84 years of age, and 55 control subjects were also assessed after receiving stoves. HRV and ST-segment values were assessed for each 30-minute period. ST-segment depression was defined as an average value below -1.00 mm. Personal fine particle (PM2.5) exposures were measured during 24 hours before each electrocardiogram.
Results: PM2.5 exposure means were 266 and 102 μg/m3 during the trial period in the control and intervention groups, respectively. During the trial, the stove intervention was associated with an odds ratio of 0.26 (95% CI: 0.08, 0.90) for ST-segment depression. We found similar associations with the before-and-after comparison. The intervention was not significantly associated with HRV.
Conclusions: The stove intervention was associated with reduced occurrence of nonspecific ST-segment depression, suggesting that household woodsmoke exposures affect ventricular repolarization and potentially cardiovascular health.