High pollution increases risk of repeated heart attacks by
over 40 percent, says TAU researcher
Air pollution, a serious danger to the environment, is also a
major health risk, associated with respiratory infections, lung
cancer and heart disease. Now a Tel Aviv University researcher has
concluded that not only does air pollution impact cardiac events
such as heart attack and stroke, but it also causes repeated
episodes over the long term.
Cardiac patients living in high pollution areas were found to be
over 40 percent more likely to have a second heart attack when
compared to patients living in low pollution areas, according to Dr.
Yariv Gerber of TAU's School of Public Health at the Sackler Faculty
of Medicine. "We know that like smoking cigarettes, pollution itself
provokes the inflammatory system. If you are talking about long-term
exposure and an inflammatory system that is irritated chronically,
pollution may well be involved in the progression of atrial
sclerosis that manifests in cardiac events," explains Dr. Gerber.
Done in collaboration with Prof. Yaacov Drory and funded by the
Environmental and Health Fund in Jerusalem, the research was
presented at the San Diego Epidemiological Meeting of the American
Heart Association in March and the Annual Meeting of the Israeli
Heart Society in April.
Risking
recurrence
Air pollution has previously been acknowledged as a factor in heart
attack risk, as well as other health risks. The goal of this study,
says Dr. Gerber, was to quantify that association and
determine the long-term effects of air pollution on myocardial
infarction (MI) patients. Their study followed 1,120 first-time MI
patients who had been admitted to one of eight hospitals in central
Israel between 1992 and 1993, all of whom were under the age of 65
at the time of admittance. The patients were followed up until 2011,
a period of 19 years.
Air quality was measured at 21 monitoring stations inareas where
the patients lived, and analyzed by a group of
researchers at the Technion in Haifa. After adjusting for other
factors such as socio-economic status and disease severity, the
researchers identified an association between pollution and negative
clinical outcomes, including mortality and recurrent vascular events
such as heart attack, stroke and heart failure.
Compared to patients who lived in areas with the lowest recorded
levels of pollution, those in the most polluted environment were 43
percent more likely to have a second heart attack or suffer
congestive heart failure and 46 percent more likely to suffer a
stroke. The study also found that patients exposed to air pollution
were 35 percent more likely to die in the almost 20 year period
following their first heart attack than those who were exposed to
lower levels of pollution.
According to Dr. Gerber, the true impact of air pollution might
be even stronger than this study shows. "Our method of assessing
exposure does have limitations. Because we are using data from
monitoring stations, it's a crude estimate of exposure, which most
likely leads to an underestimation of the association," he warns. He
estimates that air pollution could have double the negative impact
with more precise measurement.
Identifying vulnerable groups
The results of the study not only indicate a health benefit for a
public policy that curtails air pollution caused by industrial
emissions and second hand smoke, but also call for heightened
awareness by clinicians. Doctors should be making their patients
aware of the risks of remaining in high pollution areas, suggesting
that they work to limit their exposure, Dr. Gerber suggests.
Another purpose of this study was to begin identifying
populations that are vulnerable to MI and re-occurring MI.
Establishing the connection between air pollution and long-term risk
for patients with cardiovascular diseases was an important step
towards that goal.
SOURCE: Tel Aviv University