Relation between air pollution and arrhythmias

Life-threatening arrhythmias are more common on days with  highly polluted air, according to research presented at  Heart Failure 2022, a scientific congress of the  European Society of Cardiology (ESC). The study was conducted in patients with an  implantable cardioverter defibrillator which is commonly known as 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 was ranked the fourth highest risk factor for mortality after high  blood pressure,  tobacco use and  poor diet.

This study investigated the relationship between air pollution and ventricular arrhythmias in 11Piacenza, Northern Italy. The 12 European Environment Agency graded the city 307 worst out of 323 cities for annual mean PM2.5 concentrations in 2019 and 2020, with a figure of 20.8 μg/m3.

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. 79 patients had never experienced a ventricular arrhythmia, and 67 patients had previously had a ventricular arrhythmia.

Data on 13 ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) were collected remotely from the ICD until study completion at the end of 2017. The researchers also recorded the therapy delivered by the device. This included antitachycardia pacing for ventricular tachycardia (fast heartbeat), which delivers electrical impulses to the heart muscle to restore a normal heart rate and rhythm. The second therapy was an electric shock to reset the heartbeat during ventricular fibrillation.

Daily levels of PM10, PM2.5, carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3) were obtained from Regional Environmental Protection Agency(ARPA) monitoring stations. Patients were assigned exposures based on their home address. The researchers analysed the association between pollutant concentrations and the occurrence of ventricular arrhythmias.

A total of 440 ventricular arrhythmias 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 PM2.5 levels and ventricular arrhythmias treated with shocks, corresponding to a 1.5% increased risk for each 1 μg/m3 rise in PM2.5. They also found that when PM2.5 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.