- Researchers decided to explore the connection between heart health and air pollution after seeing that more heart patients made emergency room visits on days of bad air quality.
- They found that the risk of abnormal heartbeats (ventricular arrhythmias) was raised even on days when the average air quality was slightly degraded.
- The study’s authors recommend that people with implanted defibrillation devices keep an eye on daily pollution levels and plan their exposure accordingly.
New research, presented at the European Society of Cardiology’s (ESC) Heart Failure 2022 congress, compared days on which patients experienced higher numbers of ventricular arrhythmias with days scientists recorded higher levels of air pollution.
The researchers found a correlation: The days with high levels of air pollution were when most arrhythmias occurred.
Dr. Franco Folino, of the Department of Cardiac, Thoracic and Vascular Sciences at the University of Padova, Italy, told Medical News Today about the value of ICDs for research.
“These devices, as well as many pacemakers, are formidable devices not only for the treatment of arrhythmias but also for their ability to monitor heart rhythm 24 hours a day. Therefore, they represent an ideal tool for comparing arrhythmic profiles with data from the monitoring station for air quality,” he said.
However, Dr. Folino, who was not involved in the study, noted that the patients observed may be at a higher risk of pollution-related health problems.
“The research conducted on patients with ICDs, who are implanted in patients with major heart diseases, explore a population at high cardiovascular risk, highlighting that in these subjects the effects of pollution are even more pronounced,” he pointed out.
The study took place in the city of Piacenza in the Emilia Romagna region of northern Italy. In 2021, in a ranking by the European Environment Agency of European cities with the greatest levels of air pollution, Piacenza ranked near the bottom—just 16 cities were comparatively worse. The average annual concentration of particulate matter (PM) 2.5 in Piacenza was listed as 20.8 μg/m3.
The World Health Organization considers a level of 5 μg/m3 of PM 2.5 or less to be
Piacenza landed squarely in the WHO’s “poor” air quality category.
Dr. Alessia Zanni, a cardiovascular technician-technologist and author of the study, tells the ESC:
“We had observed that emergency room visits for arrhythmias in patients with ICDs tended to cluster on days with particularly high air pollution. 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.”
Dr. Zanni explained to MNT that implantable cardioverter-defibrillator (ICD) therapy is currently the only prevention tool for potentially fatal arrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF).
“The difference [between the two conditions] is that during VT, the heart can still pump some blood and the patient could still be conscious, while during VF the heart is almost still, causing a cardiac arrest,” she said.
She then went on to explain the pacing-or-shock mechanism behind ICDs.
“An ICD is capable of terminating ventricular arrhythmias by anti-tachycardia pacing (ATP), shock, or both. ATP is used for VT and tries to pace the heart faster than the arrhythmia in order to block the pathological circuit, take the lead of the heart rhythm, and then slow down the pacing until a normal heart rate is obtained,” she said.
Dr. Zanni said ICDs managed to stop ventricular tachycardia in approximately 90% of patients. Where it fails, the shock system kicks in:
“If the ATP fails, or a VF occurs, the ICD delivers a high-voltage shock that immediately stop the arrhythmia. Usually, ATP is not perceived by the patient, while the shock can be felt, even violently.”
The study tracked the ICD activity in 146 individuals who had received an implant between January 2013 and December 2017. Of this group, 67 people had experienced a previous ventricular arrhythmia, and 79 had not.
The Regional Environmental Agency provided the researchers with daily figures for PM 2.5, PM 10, carbon monoxide (CO), nitrogen oxide (NO2), and ozone (O3).
During the study, the researchers recorded 440 ventricular arrhythmias. ATP sufficed for 322 of these, while ICDs delivered a shock in 118 cases.
The study found that every 1 μg/m3 increase in PM2.5 levels corresponded with a 1.5% increased risk of arrhythmias requiring a shock.
When PM 2.5 concentrations remained elevated by 1 μg/m3 over the course of a week, ventricular arrhythmias were 2.4% more frequent. For PM 10 concentrations, a weekly increase by the same amount corresponded to 2.1% more ventricular arrhythmias.
Dr. Folino said that the study highlights the need to categorize air pollution as a risk factor for cardiovascular health.
“Air pollution must be considered in the same way as any other cardiovascular risk factor, such as smoking, hypertension, or hypercholesterolemia,” he said.
“As we fight these risk factors, in the same way, we must act to prevent people in general, but particularly those at high cardiovascular risk, from being exposed to high levels of air pollution,” he added.
Dr. Zanni also shared with the ESC some precautions heart patients can take in their everyday lives.
“When particulate matter (PM) 2.5 and PM 10 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. An air purifier can be used at home.”
— Dr. Alessia Zanni