Ventricular arrhythmias more commonly occur on days when there are higher levels of air pollution, especially with fine particulate matter (PM), a new study suggests.
The investigators studied the relationship between air pollution and ventricular arrhythmias in Piacenza, Italy by examining 5-year data on patients who received an implantable cardioverter defibrillator (ICD).
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They found a significant association between PM2.5 levels and ventricular arrhythmias, especially those treated with direct current shock. Moreover, higher levels of PM2.5 and PM10 were associated with increased risk of all ventricular arrhythmias.
“These data confirm that environmental pollution is not only a climate emergency but also a public health problem,” lead author Alessia Zanni, currently at Maggiore Hospital, Bologna, Italy, and previously at Piacenza Hospital, said in an interview.
“The study suggests that the survival of patients with heart disease is affected not only by pharmacological therapies and advances in cardiology, but also by the air that they breathe,” she said.
The results were presented at European Society of Cardiology Heart Failure 2022.
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The World Health Organization estimates around 7 million people die every year from exposure to polluted air, “as 91% of the world’s population lives in areas where air contaminants exceed safety levels,” Dr. Zanni said. Furthermore, “air pollution has been defined as the fourth-highest ranking risk factor for mortality – more important than LDL cholesterol, obesity, physical activity, or alcohol use.”
She noted that Piacenza has “historically been very attentive to the issues of early defibrillation and cardiac arrest.” Her group had previously found a correlation between out-of-hospital cardiac arrests and air pollution in the general population.
Moreover, her group recently observed that ED visits for patients with ICDs “tended to cluster; on some special days, many patients with ICDs had cardiac arrhythmias, and during those days, air pollution levels were particularly high.”
Her group therefore decided to compare the concentration of air pollutants on days when patients suffered from an arrhythmia event versus pollution levels on days without an arrhythmia, she said.
Further piece in a complex puzzle
The researchers studied 146 patients with ICDs between January 2013 and December 2017, assigning exposures (short, mid, and long term) to these patients based on their residential addresses.
They extracted day-by-day urban PM10, PM2.5, CO, NO2, and O3 levels from the Environmental Protection Agency monitoring stations and then, using time-stratified case-crossover analysis methodology, they calculated the association of ventricular arrhythmia onset with 0- to 7-day moving averages of the various air pollutants prior to the event.
Patients had received their ICD to control cardiac dysfunction brought on by previous myocardial infarction (n = 93), genetic or inflammatory conditions (n = 53), secondary prevention after a lethal arrhythmia (n = 67), and primary prevention (n = 79).
Of the 440 ventricular arrhythmias recorded, 322 were treated with antitachycardia pacing, while the remaining 118 were treated with direct current shock.
The researchers found a significant association between PM2.5 levels and ventricular arrhythmia treated with shock, corresponding to a 15% increased risk or every additional 10mg/m3 (P < .019).
They also found that, when PM2.5 concentrations were elevated by 1 mg/m3 for an entire week, compared with average levels, there was a 2.4% higher likelihood of ventricular arrhythmias, regardless of the temperature, and when PM10 was 1 mg/m3 above average for a week, there was a 2.1% increased risk for arrhythmias (odds ratio, 1,024; 95% confidence interval, 1,009-1,040] and OR, 1,021; 95% CI, 1,009-1,033, respectively), Dr. Zanni reported.
“Since the majority of out-of-hospital cardiac arrest causes still remain unclear, our data add a further piece to the complex puzzle of cardiac arrest triggers,” Dr. Zanni commented. “We think that particulate matter can cause acute inflammation of the heart muscle and potentially act as a trigger for lethal cardiac arrhythmias.
“As these toxic particles are emitted from power plants, industries, and cars, we think that cardiovascular research should highlight these new findings to promote green projects among the general population, clarifying the risks to the health of the human being, and we think strategies to prevent air pollutant exposure in high-risk patients [with previous cardiac disease] should be developed,” she added.
Further, “we advise patients at risk, during days with high PM2.5 (> 35 mg/m3) and PM10 (> 50 mg/m3) to use a mask of the N95 type outdoors, to reduce time spent outdoors – particularly in traffic – and to improve home air filtration,” Dr. Zanni said.