Pollution and weather changes like rain or heat influence outcomes after a heart attack, according to new research.
“Air pollution affects our health, especially in highly industrialised areas. We performed our research in Silesia, the most urbanised and industrialised region in Poland,” said Aneta Cislak, research fellow in the Silesian Centre for Heart Diseases, Medical University of Silesia in Zabrze, Poland.
The study examined the relationship between environmental factors and severity of clinical status and short-term prognosis in patients with non ST-segment elevation acute coronary syndromes (NSTE ACS).
These include NSTE myocardial infarction (NSTEMI) (heart attack) and unstable angina.
The study enrolled 2,388 patients admitted for NSTE ACS between 2006 and 2012.
Weather factors included atmospheric pressure, air temperature, wind speed, humidity and total solar radiation intensity measured on the day of admission.
Air concentrations of the most common pollutants (sulphur dioxide, nitric oxides, carbon monoxide, ozone and particulate matters) were recorded.
Weather and pollution parameters were correlated with clinical status expressed by left ventricular ejection fraction, a measurement of how well the heart pumps with each beat; MI rates; GRACE risk score, which assesses future risk of death or MI; and CRUSADE Bleeding Score, which assesses bleeding risk.
The researchers found that patients with high risks of MI and bleeding and low left ventricular ejection fraction were admitted for NSTE ACS on warmer, sunnier, drier and windy days with higher carbon monoxide and ozone air concentrations.
“These were the sickest patients. The findings may be explained by the fact that their organs may be more sensitive to weather changes, leading to decompensation,” said Cislak.
Treatment with percutaneous coronary intervention (PCI) to widen blocked coronary arteries was more frequently successful when the weather was sunnier and less windy but colder and with lower concentrations of ozone, carbon monoxide and nitric oxides.
“One of the possible explanations for this finding is that air pollutants like carbon monoxide bind irreversibly to haemoglobin and impair blood oxygen transport. This can cause hypoxia and lead to worse clinical status and less successful treatment,” said Cislak.
Higher in-hospital and one month mortality was observed on colder, more sunny and less windy days.
“For now, we are not able to explain this phenomenon, but we hope that further studies will help us to verify and understand it better,” said Cislak added.