LONDON – The risk for ST-elevation myocardial infarction (STEMI) increased in men when air quality dipped below acceptable levels as designated by the World Health Organization (WHO), based on the results of an observational study in Belgian.
The relative risk for a STEMI increased by 2.8% (1.026; 95% confidence interval, 1.005-1.048) for every 10 mcg/cm3 rise in fine particulate air pollution and by 5.1% (RR, 1.051; 95% CI, 1.018-1.084) for a comparable rise in nitric oxide air pollution. Ozone level was not associated with the risk for STEMI. Air pollution levels did not affect in-hospital mortality due to STEMI and had no clear effect on patients with coronary artery disease, diabetes or hypertension.
Dr. Jean-Francois Argacha
“Of course, it is very interesting that the results are only observed in men. This may be due to a statistical issue, because in our study population, the female group represents less than 25% of the population,” Dr. Jean-François Argacha, a study investigator, said during a press briefing at the annual congress of the European Society of Cardiology.
Subgroup analysis suggested that patients who were aged 75 years and older were more likely to develop STEMI in relation to exposure to particulate matter (RR, 1.046; 95% CI, 1.002-1.092, P = .041). Those aged 54 years and younger seemed more susceptible to nitric oxide levels (RR, 1.071; 95% CI, 1.010-1.136; P = .021).“The detrimental impact of nitric oxide exceeded that of fine particles and may be of particular concern in the younger population,” said Dr. Argacha, a cardiologist at University Hospital Brussels.
Previous research had shown that particulate matter is associated with an increased risk for acute myocardial infarction, but there had been no specific assessments on air pollution’s potential effects on STEMI, according to Dr. Argacha.
The study considered information on 11,428 patients in the Belgian Interdisciplinary Working Group on Acute Cardiology STEMI Registry between 2009 and 2013. Data on national air pollution parameters – particulate matter with an aerodynamic diameter of less than 10 (PM10) or 2.5 (PM2.5) mcm, nitric oxide and ozone – and air temperature were obtained from the Belgian Environment Agency database and adjusted for population density.
A case crossover analysis of STEMI risk was then performed, with risk being adjusted for ambient temperature, day of the week, and the season. The study’s case crossover design ensured that the effects were limited to air pollution and excluded other confounders including respiratory disease and air temperature.
Worldwide, WHO has estimated that poor urban air quality is responsible for around 1.3 million deaths per year, Dr. Argacha observed, noting that air pollution consists of fine (PM2.5) and larger (PM10) particles, nitric oxide, and ozone as well as sulfur dioxide and carbon monoxide.
During the observation period, the mean air pollution levels over the course of 1 year in Belgium were 23.9 mcg/cm3 for PM10, 16.1 mcg/cm3 for PM2.5, and 23.7 mcg/cm3 for nitric oxide. WHO guidelines set a daily limit of 25 mcg/cm3 for PM2.5. Dr. Argacha noted that this limit was exceeded in Belgium on 17.5% of days in the study.
Dr. Oscar Franco, professor of preventative medicine at the Erasmus University Medical Center in Rotterdam, the Netherlands, who cochaired the press conference noted that the European Society of Cardiology recently published a position paper on air pollution on cardiovascular disease (Eur Heart J. 2015;36:83-93) and has launched a major campaign to raise awareness of the detrimental effects that the environment can have on the heart.
The campaign notes that air and noise pollution are modifiable risk factors for the prevention and control of cardiovascular diseases, and advocated for acceptable limits that reflect WHO levels. Individuals “need to take action,” Dr. Franco urged. The decisions that people make every day – how they get to work for example – could have a potentially huge impact on the environment and health.
Dr. Argacha and Dr. Franco had no disclosures to report.