Research Highlights:
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Summary
Background
Exposure to fine particles (fine particles with aerodynamic diameters ≤2.5 μm [PM2.5]) has been associated with a risk of cardiac arrhythmias in adults. However, the association between PM2.5 exposure and cardiac arrhythmias in adolescents remains unclear.
Methods and Results
To investigate the association and time course between PM2.5 exposure and cardiac arrhythmias in adolescents, we analyzed data collected from 322 adolescents who participated in the PSCC ( Penn State Child Cohort ) follow-up examination. We obtained 24-hour PM2 concentrations at the individual level with a nephelometer. Simultaneously with the PM2 measurement, we obtained 24-hour ECG data using a Holter monitor, from which cardiac arrhythmias, including premature atrial contractions and premature ventricular contractions (PVCs), were identified. PM2 concentration and number of premature atrial contractions/PVC were summarized in segments based on 30 minutes. Distributed delay polynomial models within a negative binomial model framework were used to evaluate the effect of PM2 concentration on the number of premature atrial contractions and PVCs.
Exposure to PM2.5 was associated with an acute increase in the number of PVCs.
Specifically, a 10 μg/m3 increase in PM2.5 concentration was associated with a 2% (95% CI, 0.4%–3.3%) increase in PVC counts from 0.5 to 1.0, 1.0 to 1.5 and 1.5 to 2.0 hours after exposure. Cumulatively, a 10 μg/m3 increase in PM2 was associated with a 5% (95% CI, 1%–10%) increase in PVC counts within 2 hours of exposure. PM2.5 concentration was not associated with premature atrial contraction.
Conclusions
Exposure to PM2.5 was associated with an acute increase in the number of ventricular arrhythmias in a sample population of adolescents. The time course of the effect of PM2 on ventricular arrhythmia is within 2 hours of exposure.
Comments
Breathing particles (that is, tiny particles suspended in the air) from air pollution can trigger irregular heart rhythms (arrhythmias) in healthy adolescents, according to new research published in the Journal of the American Heart Association , a peer-reviewed open access journal. by peers from the American Heart Association.
While the negative cardiovascular effects of air pollution in adults have already been established, this study is the first to evaluate the impact of air pollution on adolescents in the general population.
“Although relatively rare, irregular heart rhythms can lead to sudden cardiac death in healthy adolescents and young adults. “Our findings linking air pollution to irregular heart rhythms suggest that particles may contribute to the risk of sudden cardiac death among young people,” said Fan He, Ph.D., lead author of the study and instructor in public health sciences. at the University of Pennsylvania. State Medical College in Hershey, Pennsylvania. “Given that cardiovascular conditions from childhood and adolescence can continue into adulthood and affect the risk of major cardiovascular diseases later in life, the identification of modifiable risk factors for cardiac arrhythmia that may cause sudden cardiac death among adolescents should be of great public interest.”
The study examined the impact of breathing fine particles on the heart rate of adolescents. Fine particles ( PM2.5) are less than 2.5 microns in size and can be easily inhaled deep into the lungs and even enter the bloodstream. Particles smaller than 2.5 microns are usually related to fuel combustion, such as particles from car exhaust or forest fires . Once inhaled, pollutants irritate the lungs and blood vessels around the heart, and previous research has suggested that, over time, pollutants increase the disease process in the arteries.
The researchers looked at the impact of breathing particulate pollution on two types of irregular heart rhythms characterized by premature contraction in the heart muscle (extrasystole). In premature atrial contractions (PAC), the heartbeat originates in the atria (upper chambers of the heart). This usually causes no symptoms or damage; However, premature and frequent atrial contractions have been linked to an increased risk of atrial fibrillation, a serious form of arrhythmia in which the upper chambers shake instead of beating effectively, increasing the risk of blood clots and stroke. . Premature ventricular contractions (PVCs) occur when the heartbeat originates in one of the ventricles (lower chambers of the heart). These also increase the risk of a heart attack, stroke, heart failure, or sudden cardiac death later.
If premature contractions do not cause symptoms, they are not treated. However, if they occur frequently and result in the frequent sensation of a stopped heartbeat, rapid heartbeat, or palpitations, treatment with medications, devices, or implantable procedures may be recommended.
Researchers analyzed health data from 322 adolescents (mean age 17 years; 56% male; 79% non-Hispanic white adolescents) living in central Pennsylvania who participated in a follow-up assessment in the Penn State Child Cohort study. That study, conducted between 2002 and 2006, initially recruited children ages 6 to 12. The data analyzed in this study reviewed the results of the follow-up evaluation almost 7.5 years later (2010-2013).
This group of children did not have major cardiovascular conditions and were considered at low risk for irregular heart rhythms. In the follow-up study, researchers simultaneously measured exposure to fine particles in the air that each teen breathed (using a device called a nephelometer) for 24 hours and EKG recordings of each teen’s heart rhythms through a small device. portable monitor called a Holter monitor.
The average PM2.5 concentration measured in the study was approximately 17 micrograms of particles per cubic meter of air (µg/m3) per day, which is well below the health-based air quality standard of 35 µg/m3. m3 established by the United States Environmental Protection Agency (EPA).
The study found:
- 79% of participants had at least one irregular heartbeat during the 24-hour study period. Of that group, 40% had only premature atrial contractions, 12% had only premature ventricular contractions, and 48% had both.
- A 5% increase in the number of premature ventricular contractions was observed within two hours of exposure for every 10 µg/m3 increase in PM2.5.
- No association was found between the concentration of particulate matter and the number of atrial extrasystoles.
“It is alarming that we could see such a significant impact of air pollution on cardiac arrhythmias when air quality remained within health standards established by the EPA. It may suggest that adolescents living in highly polluted areas, such as inner cities, are at even greater risk,” she said.
The results were consistent with data previously obtained in adults using similar methods by these researchers and others, although the increase in premature ventricular contractions was even greater in adults. Reducing the risk of irregular heart rhythms in adolescents could reduce their risk of developing heart disease in adulthood, according to the study authors.
“Our study found that air pollution increases the risk of cardiovascular disease and sudden cardiac death , even among healthy adolescents,” he said. “Protective measures, such as wearing masks and avoiding vigorous physical activities, may be justified on days when particle concentrations are high, especially during morning peak hours.”
The most effective way to reduce everyone’s exposure to air pollution is to support stricter air quality regulations nationwide, said American Heart Association volunteer expert Robert D. Brook, MD, FAHA, professor of medicine. at Wayne State University in Detroit. Brook is a co-author of several American Heart Association scientific statements on air pollution.
“PM2.5 levels have decreased dramatically since the 1970s and 1980s due to regulations that have certainly been linked to improved health effects and life expectancy,” Brook said. “We describe in a recent AHA scientific statement , titled Personal Protective Actions Against Exposure to Particulate Air Pollution, strategies and activities or behavioral changes that can reduce pollution exposure, such as portable air filters, face masks, respirators and exercise during non-peak hours. However, there have been no studies showing that these measures can actually prevent adverse clinical health effects, such as heart attacks.”
According to a 2020 American Heart Association policy statement citing a global study, ambient air pollution is widely recognized as a significant contributor to cardiovascular disease and death. In 2017, exposure to particulate air pollution was estimated to be associated with more than 7 million premature deaths and the loss of 147 million healthy life years worldwide. The Association recommends further development of evidence-based policy approaches, continued investment in research, and increased innovation and transformative partnerships to reduce the cardiovascular burden of ambient air pollutants in the US.
"The most interesting and significant aspect of this study is clearly that the results were found in healthy young adolescents," Brook said. “The study supports concerns that even healthy young people are not immune to adverse cardiovascular responses to PM2.5 and exposure levels within the 24-hour National Ambient Air Quality Standards established by the EPA. "It is plausible that the findings help explain the potential reason for the timing of onset of arrhythmias and even sudden death in some susceptible young people."
Dr. He and his colleagues are currently evaluating the impact of air pollution on other markers of cardiac electrical activity. This study was limited by not being able to analyze the impact of air pollution on different subtypes of premature ventricular contractions, which may help cardiologists better understand how pollution affects cardiac function. The results of this study in adolescents may not be generalizable to younger children.
Clinical Perspective
What’s new?
The current study is the first of its kind to show an acute association between fine particulate air pollution with aerodynamic diameters ≤2.5 μm and ventricular arrhythmia in a population sample of adolescents.
The time course of the impact of air pollution on ventricular arrhythmia was within ≈2 hours after exposure.
What are the clinical implications?
Due to the ubiquitous and involuntary nature of air pollution, air pollution control measures can be taken to reduce the risk of cardiac arrhythmia in adolescents.
Reducing the risk of cardiac arrhythmia during adolescence may further reduce the burden of cardiovascular disease in adults due to the importance of early prevention of cardiovascular disease early in life.
sudden cardiac death
Sudden cardiac death (SCD) is a major public health threat. SCD is estimated to account for ≈50% of cardiovascular disease-related deaths and 15% to 20% of all-cause mortality in Western countries. Although relatively rare, SCD among healthy children and young people, including elite athletes, has a devastating impact on their families. Furthermore, considering the large number of years of life lost, the public health burden related to SCD in young people is not trivial. As a result, the causes of SCD in children and young people have been widely studied. Unlike older adults, among whom atherosclerotic coronary artery disease is the predominant cause of SCD, cardiac arrhythmia is one of the most prominent risk factors for SCD in young people. For example, unexplained SCD (i.e., SCD with no apparent cause after a complete autopsy), which can be primarily attributed to cardiac arrhythmias, accounts for one-third of SCD among children and young adults. Therefore, it is of great public health importance to identify modifiable risk factors for cardiac arrhythmias among children and adolescents.
The occurrence of cardiac arrhythmias can be attributed to impairment of cardiac autonomic balance, systemic inflammation, and oxidative stress. With these biological processes it is plausible that exposure to PM2 is also related to an increased risk of cardiac arrhythmias . Indeed, the association between PM2 and cardiac arrhythmias has been observed in epidemiological studies in adults based on mortality data, arrhythmia episodes captured by implantable cardioverter-defibrillator, and ECG monitoring. For example, long-term exposure to PM2 has been associated with increased mortality from arrhythmias , especially among smokers. Furthermore, acute exposure to PM2 has been associated with increased odds of atrial fibrillation recorded by an implantable cardioverter defibrillator within a few hours of exposure16. In both the general adult population and in patients with cardiovascular diseases, exposure to environmental particles has also been associated with ventricular arrhythmias on ECG monitoring.
Although these studies have provided compelling evidence supporting PM2 exposure as a risk factor for cardiac arrhythmias, almost all were conducted in adults, including patients with pre-existing cardiovascular diseases. Therefore, the findings cannot be generalized to low-risk populations, such as adolescents who do not have underlying cardiovascular diseases. Given the paramount importance of arrhythmias in the cause of SCD among young people, there is an urgent need to understand whether PM2 exposure triggers cardiac arrhythmias in young people.
Therefore, we conducted this study to evaluate the association between ambient PM2.5 concentration and cardiac arrhythmias in a sample population of adolescents. Our hypothesis is that the elevated level of PM2.5 is associated with an acute increase in the number of cardiac arrhythmias within a few hours of exposure.
Co-authors are Jeff D. Yanosky, Sc.D.; Julio Fernández-Mendoza, Ph.D.; Vernon M. Chinchilli, Ph.D.; Laila Al-Shaar, Ph.D.; Alexandros N. Vgontzas, MD; Edward O. Bixler, Ph.D.; and Duanping Liao, M.D., Ph.D.
