Cardiovascular disease is common worldwide, and the list of risk factors contributing to the condition is well known. According to a new study, aircraft noise should be added as a factor contributing to heart attacks and worsening outcomes.
As a form of cardiovascular disease, heart failure caused by a heart attack, known medically as myocardial infarction (MI), is a leading cause of death worldwide.
According to the Centers for Disease Control and Prevention (CDC), in the US, someone has an MI every 40 seconds. In Australia in 2020, the number of “acute coronary events” – which includes MI and unstable angina – in people aged 25 and over was around 155 per day.
The risk factors for cardiovascular disease are well-known: familial history, high blood pressure, high cholesterol, diabetes, smoking, obesity, unhealthy diet and physical inactivity. Now, it seems researchers at the University Medical Center in Mainz, Germany, have added exposure to aircraft noise to that list.
Previous studies have confirmed that noise generated by aircraft, road traffic and railways causes the body to release stress hormones, leading to an inflammatory response. And that inflammation of the blood vessels, one of the telltale signs of cardiovascular disease, increases a person’s risk of MI.
In the current study, researchers examined the mechanisms underlying heart and blood vessel inflammation and how exposure to aircraft noise affected those mechanisms. They exposed mice to aircraft noise 24 hours a day for up to four days. The noise averaged 72 dB and peaked at 85 dB. For comparison, a normal conversation ranges between 60 and 70 dB, an alarm clock is 70 to 80 dB, and a vacuum cleaner produces noise between 60 and 80 dB.
Testing showed that noise exposure alone caused inflammatory cells to stick to the tissues of the heart and blood vessels. Next, the researchers induced an MI in the mice by tying off one of the main blood vessels supplying the heart. Mice exposed to noise before the MI showed deteriorating heart function and a larger area of heart muscle damage after the MI, caused by the increased immune response.
The study demonstrates that noise alone can lead to an inflammatory response that negatively affects heart function. After an MI, pre-exposure to noise exacerbates the body’s response, causing more damage to the heart muscle and greater impairment.
Researchers compared their data with data collected by the Gutenberg Health Study (GHS), a long-term representative population study of over 15,000 individuals. They found the data comparable, meaning that the negative effects of aircraft noise on heart function in mice were also seen in humans.
“We learned from our studies that aircraft noise exposure before MI substantially amplifies subsequent cardiovascular inflammation and aggravates ischemic heart failure,” said lead and senior authors Michael Molitor and Philip Wenzel.
The researchers suggest that exposure to environmental noise is considered a risk factor for cardiovascular disease. In addition to addressing other known risk factors, reducing environmental noise might improve the clinical outcomes of people who have suffered a heart attack.
The study was published in the journal Cardiovascular Research.
Source: University Medical Center Mainz via EurekAlert!