Studies Address Impacts of Environmental Factors on CV Health
Environmental factors and their impacts on cardiovascular disease was the subject of several new studies presented Aug. 30 during ESC Congress 2015 in London.
One study out of Winnipeg, Canada, looked at the effects of temperature on the risk of heart attacks. The six-year study found that each 10 degree Celsius drop in temperature was associated with a 7 percent increased risk of ST-elevation myocardial infarction (STEMI). Of the 1,817 STEMIs over the six years, the daily high was the strongest predictor of STEMI. On days with a daily high less than 0 degrees Celsius, STEMI event rates were 0.94/day, compared to 0.78/day when the daily high was greater than 0 degrees Celsius. Despite yearly variation, the average STEMI rate over the study period had a statistically significant linear trend across temperature (p<0.001). Daily high in the preceding one or two days was also predictive (p<0.001). Warmer temperature ranges were not associated with higher STEMI.
"Our study highlights the potential influence of the environment on occurrence of STEMI," said Shuangbo Liu, MD, of the University of Manitoba. "These findings create an opportunity for future research studies to examine whether there are treatment strategies that can temper the effects of climate on the risk of heart attacks."
Another study out of Belgium found an association between particulate matter and NO2 air pollution and an increased risk of severe heart attacks. They study compared data on PM10, PM2.5, O3 and NO2 levels from Belgian Environmental Agency air pollution records with data on STEMI incidence from the Belgian Interdisciplinary Working Group on Acute Cardiology STEMI registry. Researchers found that 10 μg/m3 increases in ambient PM2.5 concentrations were associated with a 2.8 percent increase in STEMI while 10 μg/m3 rises in NO2 were associated with a 5.1 percent increased risk. These associations were only observed in men. Additionally, a subgroup analysis showed that patients aged 75 years and above developed more STEMI in relation to PM10 exposure, while those 54 years and under were more susceptible to NO2.
"The association between STEMI and air pollution was observed within one day of exposure," said Jean-Francois Argacha, MD, of University Hospital Brussels. "This was despite the fact that concentrations of air pollutants were within the European air quality standard. It's possible that only men were affected because of the under representation of women in our study population (less than 25 percent). Nevertheless, previous studies have demonstrated that blood pressure, arterial stiffness and heart rate variability abnormalities secondary to air pollution exposure are more pronounced in men. Sex differences in obesity and blood inflammation may worsen air pollutant effects but this hypothesis requires further investigation."
Meanwhile, a separate study out of Poland also looked at the impacts of air pollution on cardiovascular health, but focused on young adults aged 16 to 22 years living in large cities. Researchers measured blood pressure, heart rate and blood levels of inflammatory markers including C-reactive protein (CRP), high sensitivity CRP (hsCRP), homocysteine and fibrinogen. They also assessed several potential confounding factors like body mass index (BMI), lifestyle, ethnicity and family history. Data on air pollution was obtained from air quality monitoring stations.
Results found significantly higher levels of CRP, hsCRP, homocysteine and fibrinogen levels in residents of Krakow, the most polluted city, compared to residents of Lublin, a less-polluted city (p<0.0001 for all). The highest levels of these inflammatory markers was found in overweight (BMI 25-37 kg/m2) participants living in Krakow. There were no major differences in subjects' blood pressure between the two cities, nor were there differences in smoking, physical activity levels, BMI, age or other confounding factors.
Pollution and weather can also influence outcomes after a heart attack, according to another study out of Poland presented by Aneta Cislak, research fellow in the Silesian Centre for Heart Diseases, Medical University of Silesia in Zabrze. The study of 2,388 patients admitted for non ST-segment elevation acute coronary syndromes (NSTE ACS) between 2006 and 2012, found that those with high risks of myocardial infarction and bleeding and low left ventricular ejection fraction were admitted on warmer, sunnier, drier and windy days with higher carbon monoxide and ozone air concentrations. Additionally, treatment with percutaneous coronary intervention 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. Higher in-hospital and one-month mortality was observed on colder, more sunny and less windy days.
"This was a small observational study and our analysis was univariate so we cannot rule out the possibility that the associations were caused by the co-existence of other factors," said Cislak. However, she noted the findings do suggest that "environmental factors may affect the severity of clinical status and short-term prognosis in patients with NSTE ACS." Moving forward, a study investigating the impact of meteorology and air pollution on 600,000 patients in the Silesian Cardiovascular Database who were hospitalized with cardiovascular diseases in the last 10 years is underway.
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