Researchers who performed MRI scans on the heart found that long-term exposure to air pollution is linked to early signs of heart damage. This is according to a study published in the Radiology journal of the Radiological Society of North America (RSNA). The research findings suggest that particulate matter in the air may contribute to diffuse myocardial fibrosis, a form of scarring of the heart muscle that can precede heart failure.
How Air Pollution and Heart Disease are Linked
Cardiovascular disease is the leading cause of death worldwide. There is ample evidence of a link between poor air quality and cardiovascular disease. However, the underlying changes in the heart caused by exposure to air pollution are unclear. “We know that people exposed to air pollution have a higher risk of heart disease, including a higher risk of heart attack,” said the study’s lead author, Kate Hanneman, M.D., M.P.H., of the Department of Medical Imaging at the University of Toronto’s Temerty Faculty of Medicine and University Health Network in Toronto. The researchers wanted to understand what causes this increased risk at the tissue level.
Dr. Hanneman and her colleagues used cardiac MRI, a non-invasive imaging method, to quantify myocardial fibrosis and assess its association with long-term exposure to particulate matter, known as PM2.5. With a diameter of 2.5 micrometers or less, PM2.5 particles are small enough to enter the bloodstream through the lungs. The most common sources include vehicle exhaust, industrial emissions and smoke from forest fires. The researchers wanted to investigate the effects of air pollution on both healthy people and people with heart disease. Therefore, the study group included 201 healthy controls and 493 patients with dilated cardiomyopathy, a condition that makes it difficult for the heart to pump.
Higher long-term exposure to particulate matter pollution was associated with higher levels of myocardial fibrosis in both patients with cardiomyopathy and control subjects, suggesting that myocardial fibrosis may be an underlying mechanism by which air pollution leads to cardiovascular complications. The greatest effects were observed in women, smokers and patients with hypertension. The study adds to the growing evidence that air pollution is a cardiovascular risk factor that contributes to a residual risk not captured by conventional clinical predictors such as smoking or hypertension.
Better Risk Assessment
Even a moderate increase in air pollution appears to have measurable effects on the heart. The study suggests that air quality may play an important role in changes in cardiac structure, and could potentially lay the foundation for future cardiovascular disease. According to the researchers, knowing a patient’s long-term exposure to air pollution could help refine risk assessment for heart disease and address the health disparities that air pollution contributes to, both in terms of exposure and impact. For example, if a person works outdoors in an area with poor air quality, healthcare providers could incorporate this exposure history into heart disease risk assessment.
The air pollution levels of the patients in the study were below many global air quality guidelines, reaffirming that there are no safe exposure limits. The study not only sheds light on the link between air pollution and myocardial fibrosis, but also emphasizes the important role radiologists will play in future research and clinical development. “Medical imaging can be used as a tool to understand the impact of the environment on a patient’s health,” said Dr. Hanneman. “As radiologists, we have a great opportunity to use imaging to identify and quantify some of the health effects of environmental exposures on various organ systems.”