Heart patients should avoid traffic pollution, stated a recent US study. According to the study, traffic pollution can hinder heart’s ability to conduct electrical signals. The researchers at Harvard University said that people who have serious coronary artery disease could have problems from the tiny particles emitted from air pollution as well as the black carbon from exhaust fumes that could cause ST segment depression. This usually indicates an inadequate supply of oxygen and blood flow to the heart.

Published in Circulation: Journal of the American Heart Association, the study was based on the electrocardiograms of 48 patients who had been hospitalized for heart attack, unstable angina or deteriorating symptoms of coronary heart disease over the period of a year. The subjects wore special monitors that intermittently checked for ST-segment depression during the study period.

According to lead researcher Dr. Diane R. Gold, an associate professor of medicine and environmental health at Harvard University and her team, with an increase in the particles and black carbon in the air, a corresponding increase was seen in instances of ST-segment depression. The effects were the most within the first month after hospitalization and for patients who had been hospitalized for a heart attack or had diabetes.

"Our study provides additional rationale to avoid or reduce heavy traffic exposure after discharge, even for those without a heart attack, since traffic exposure involves pollution exposure as well as stress," said Gold.

The American Heart Association and the American College of Cardiology recommend that some heart patients, particularly those who have had heart attacks, should avoid driving for several weeks, especially in heavy traffic, because of the stress.

Researchers are still not sure how the carbon and air particles cause ST-segment depression, but they are recommending that heart-disease patients should limit their time outdoors if they live in a highly polluted city. Further research is needed to conclusively establish whether the pollution-related ST-segment depression.

"Further research is needed to evaluate whether the pollution-related ST-segment depression that we see is related to increased heart muscle inflammation, reduced oxygen flow, oxidative stress, or increased risk of arrhythmias," said Gold.

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