Dirty air linked with premature death in patients with heart failure

Heart failure patients are at increased risk of dying from their condition on polluted days and up to two days afterwards, according to research presented today at Heart Failure 2023, a scientific congress of the European Society of Cardiology (ESC).

"The findings indicate that reducing air pollution has the potential to prevent worsening heart failure," said study author Dr. Lukasz Kuzma of the Medical University of Bialystok, Poland. "Protecting vulnerable groups, especially during winter, should become an integral part of clinical care. That means health professionals working with patients to monitor air quality and choose optimal times for outdoor activity."

Air pollution is the single biggest environmental threat to human health, according to the World Health Organization (WHO). This includes particulate matter (PM)2.5 and PM10, of which major sources are vehicle exhaust emissions and industry fumes. Ambient air pollution caused an estimated 4.2 million premature deaths globally in 2019.

Heart failure affects more than 64 million people worldwide. The authors of the current study previously found that rises in particulate matter were associated with increased hospitalizations for heart failure. This study examined the relationship between smog exposure and short-term mortality from heart failure.

Mortality data from the five main cities in Eastern Poland during 2016 to 2020 were obtained from the Central Statistical Office. Concentrations of PM2.5 and PM10 were retrieved from the Inspectorate for Environmental Protection. Home post codes were used to connect individual pollution exposure with mortality.

The researchers used a time-stratified case-crossover study design in which participants served as their own controls. This eliminated the potential confounding effect of individual characteristics. For each participant, pollutant levels on the day of the week a death occurred (e.g. Tuesday) were compared with pollutant levels on the same day of the week with no deaths (e.g. all remaining Tuesdays) in the same month. The analyses were repeated for pollution levels one day and two days before a death took place.

All analyses were adjusted for factors that could influence the relationships including the time of year, day of the week, weather conditions (temperature, humidity and atmospheric pressure) and long-term trends such as population demographics.

A total of 87,990 deaths were recorded during the five-year study, of which 7,404 were due to heart failure. The average age of those who died from heart failure was 74 years and 49% were women. The highest number of deaths occurred in winter and the lowest in summer, with averages of 1.03 and 0.69 per day, respectively.

A 10 μg/m³ increase in PM2.5 and PM10 was associated with a 10% and 9% rise, respectively, in the risk of death due to heart failure on the polluted day. Similar risks of dying from heart failure were observed one and two days following smog exposure.

Dr. Kuzma said, "The results suggest that pollution continues to exert negative effects on heart health for two days after smog exposure. Patients with heart failure should minimize their time in polluted areas, for example by avoiding outdoor activities in places with dense traffic or when pollution levels are high, and using air filters at home. In addition, patients can advocate for policies and actions to improve air quality in their communities."

He concluded, "Our research indicates that considering the impact of pollution in public health measures to prevent disease and the consequences of ill health could lead to positive outcomes for patients with heart failure. Such measures should be taken in parallel with clinical care to improve the prognosis of this condition."