Air pollution linked to heart rhythm disorder

Life-threatening arrhythmias are more common on days with highly polluted air, according to research presented last month at the European Society of Cardiology’s Heart Failure 2022 congress. The study was conducted in patients with an implantable cardioverter defibrillator (ICD), enabling the authors to track the occurrence of arrhythmias and delivery of life-saving therapy.

Outdoor air pollution kills an estimated 4.2 million people every year, according to the World Health Organization. Nearly one in five cardiovascular disease deaths are due to dirty air, which is ranked the fourth-highest risk factor for mortality after high blood pressure, tobacco use and poor diet.

The new study investigated the relationship between air pollution and ventricular arrhythmias in Piacenza, Northern Italy. The European Environment Agency graded the city at number 307 out of 323 cities for annual mean particular matter (PM)_2.5 concentrations in 2019 and 2020, with a figure of 20.8 μg/m³.

“We had observed that emergency room visits for arrhythmias in patients with ICDs tended to cluster on days with particularly high air pollution,” said study author Dr Alessia Zanni, who was previously based at Piacenza Hospital. “We therefore decided to compare the concentration of air pollutants on days when patients had an arrhythmia versus pollution levels on days without an arrhythmia.”

The study included 146 consecutive patients who received an ICD between January 2013 and December 2017. Of those, 93 received an ICD because of heart failure after a heart attack, while 53 had a genetic or inflammatory heart condition. Just over half (79 patients) had never experienced a ventricular arrhythmia, and 67 patients had previously had a ventricular arrhythmia.

A total of 440 ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) were recorded during the study period, of which 322 were treated with antitachycardia pacing and 118 were treated with a shock. The researchers found a significant association between PM_2.5 levels (based on patients’ home address) and ventricular arrhythmias treated with shocks, corresponding to a 1.5% increased risk for each 1 μg/m³ rise in PM_2.5. They also found that when PM_2.5 concentrations were elevated by 1 μg/m³ for an entire week, compared to average levels, there was a 2.4% higher likelihood of ventricular arrhythmias regardless of the temperature. When PM₁₀ was 1 μg/m³ above average for a week, there was a 2.1% raised risk of arrhythmias.

“Particulate matter may cause acute inflammation of the heart muscle, which could act as a trigger for cardiac arrhythmias,” Zanni said. “As these toxic particles are emitted from power plants, industries and cars, green projects are needed to protect health, on top of the actions individuals can take to protect themselves.

“Our study suggests that people at high risk of ventricular arrhythmias, such as those with an ICD, should check daily pollution levels. When particulate matter (PM)_2.5 and PM₁₀ concentrations are high (above 35 μg/m³ and 50 μg/m³, respectively), it would be sensible to stay indoors as much as possible and wear an N95 mask outside, particularly in areas of heavy traffic.”

Image credit: ©stock.adobe.com/au/motortion

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