Environmental Noise Linked to Increased Cardiovascular Risk

November 09, 2018

Further evidence that people living in areas with high levels of environmental noise have a higher risk for cardiovascular events has come from a new study.

The study also suggests that this link is mediated by increased activity in the amygdala, an area of the brain involved in stress response and thought to trigger arterial inflammation.

"We found that people living in areas with a higher level of noise had increased activity in the amygdala, showing a higher level of stress perception," lead author Azar Radfar, MD, Massachusetts General Hospital, Boston, told theheart.org | Medscape Cardiology. "They also had higher levels of arterial inflammation and cardiovascular events. The results were the same after adjustment for many confounders, including air pollution.

She added that they can't yet say that noise is a causal risk factor for cardiovascular disease; larger, longitudinal studies and research assessing interventions will be required for that.

"But our results strengthen the link between environmental noise and cardiovascular risk," she said. "While we all currently focus on the known cardiovascular risk factors, such as diabetes, blood pressure, and cholesterol, we believe that, going forward, environmental factors, including noise levels, also need to be considered when thinking about the risks for cardiovascular disease."

Patients and their physicians should consider chronic noise exposure when assessing cardiovascular risk and might want to take steps to minimize or mitigate such chronic exposure, Radfar said.

The study is to be presented at the upcoming American Heart Association Scientific Sessions 2018.

Important Results

In a Skype "perspective" on the study, American Heart Association volunteer expert, Richard C. Becker, MD, University of Cincinnati Heart, Lung & Vascular Institute, described the results as "important and intriguing."

For the study, the researchers analyzed the association between noise exposure and major cardiovascular events in 499 individuals who were free of cardiovascular disease and cancer.

A subset of 281 subjects also underwent validated PET/CT imaging to assess arterial inflammation, and amygdalar activity, which was measured by uptake of the radiotracer fluorodeoxyglucose (FDG). 

To gauge noise exposure, the researchers used the home addresses of the participants and derived noise-level estimates from the Department of Transportation's Aviation and Highway Noise Map.

The medical records of the participants were analyzed over a median follow-up of 3.7 years for the occurrence of cardiovascular events.

Results showed that individuals who lived in the areas with the highest levels of noise exposure had higher levels of amygdalar activity and more arterial inflammation.

Patients living in areas in the highest quartile of noise exposure had an amygdala/background brain FDG uptake ratio of 0.85, compared with 0.78 for those in the other three quartiles (P < .001).

During follow-up, 40 individuals experienced a major adverse cardiovascular event, with those in the highest quartile for noise exposure having more than a threefold higher risk for an event (hazard ratio, 3.35; P < .001).

This remained significant after adjustment for other cardiovascular risk factors and air pollution (= .003).

American Heart Association (AHA) Scientific Sessions 2018: Abstract Su1287. To be presented November 11, 2018.


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