Regional air pollution severity affects the incidence of acute myocardial infarction triggered by short-term pollutant exposure: A time-stratified case-crossover analysis

DOI: https://doi.org/10.21203/rs.3.rs-432348/v1

Abstract

Background

 Long-term exposure to air pollution results in a high incidence of cardiovascular disease. Whether acute myocardial infarction is triggered by short-term exposure to air pollution is related to the average severity of air pollution in the area.

Design

Case-crossover analysis.

Methods

This was a retrospective study based on hospital medical records. The study period was 2017-2018. Research data were collected from Taoyuan Hospital, which is located in a low-severity pollution area, and Taichung Hospital, which is in a high-severity pollution area, and the correlation between short-term air pollution exposure and acute myocardial infarction was analyzed.

Results

The correlation between short-term exposure to ambient air pollutants and acute myocardial infarction was not significant for the cases collected from Taoyuan Hospital (PM2.5 OR: 1.006 & 95% CI: 0.995-1.017; PM10 OR: 0.996 & 95% CI: 0.988-1.003). However, for the cases collected from Taichung Hospital, short-term exposure to ambient PM2.5 (odds ratio: 1.021; 95% confidence interval: 1.002-1.040) and PM10 (odds ratio: 1.010; 95% confidence interval: 1.001-1.020) resulted in high incidence of acute myocardial infarction.

Conclusions

Short-term pollutant exposure will increase the incidence of acute myocardial infarction based on the severity of regional air pollution. In addition to addressing traditional cardiovascular disease risk factors, the government must formulate relevant policies for reducing air pollution and thus the hazards to national health.

Introduction

Acute myocardial infarction is the main disease leading to poor human health (WHO 2016). It poses a heavy financial burden on families and requires considerable society-based treatment. Through national health policy, governments have been investing considerable effort into reducing the incidence of myocardial infarction. Instead of investigating the traditional risk factors for myocardial infarction, scholars are increasingly focusing on the correlation between air pollution and cardiovascular disease (Miller et al. 2007 ; Brook et al. 2004 ; Pope et al. 2006 ; Xie et al. 2015).

The main pathophysiological framework used to explain the epidemiological association between exposure to ambient air pollutants and acute myocardial infarction is an increase in the mean resting arterial blood pressure due to an increase in the sympathetic tone and regulation of potential systemic vascular tone. By transiently increasing plasma viscosity and the amount of endothelial function damage, the risk of intravascular thrombosis is increased, promoting the development of atherosclerosis (Brook et al. 2002 ; Pekkanen et al. 2002 ; Sun et al. 2010).

Most studies have discovered that long-term exposure to ambient air pollutants increases the incidence of cardiovascular disease. However, whether short-term exposure to ambient air pollutants can trigger acute myocardial infarction remains controversial (Kathrin et al. 2015 ; Janine et al. 2014 ; Ai et al. 2014).

This study investigated whether an observed difference in the occurrence of short-term exposure to ambient air pollutants and the incidence of acute myocardial infarction was due to differing severities of ambient air pollution in the study area.

Materials And Methods

This study was conducted at Taoyuan Hospital and Taichung Hospital, which are 450-bed academic regional Emergency Responsibility Teaching Hospital; these hospitals are located in Taoyuan and Taichung, Taiwan (R.O.C.), respectively. Taoyuan Hospital and Taichung Hospital are located in areas with low-severity and high-severity air pollution, respectively. Data were obtained from a retrospective review of patient medical records. The data were the date of illness onset, sex, age, body mass index, hypertension, hyperlipidemia, diabetes, smoking, drinking, and heart disease history of the patient and patient's family. This retrospective study involved 352 patients in Taoyuan and 278 patients in Taichung who received a diagnosis of acute myocardial infarction through cardiac catheterization from January 2017 to December 2018. Nonlocal workers or residents were excluded.

The Air Quality Monitoring Station of the Environmental Protection Agency of the Executive Yuan provided information on environmental air pollutants. Each monitoring station obtains hourly air pollutant data and provides the 24-hour-average daily concentration of pollutants, including PM2.5, PM10, O3, SO2, and NO2 as well as the temperature and humidity.

We examined the associations between short-term air pollutant exposure and acute myocardial infraction by using a time-stratified case-crossover design. The levels of ambient air pollutants on the date of illness onset were compared with those 2 weeks before the onset. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using Poisson regression in the generalized linear model. Models were adjusted for average temperature and relative humidity on the day of an event.

Categorical variables were compared between groups using the χ2 test and Student's t test; continuous variables are presented as mean ± standard deviation and were compared using the t test. P < 0.05 was considered statistically significant. Data analyses were performed using SPSS version 22 (SPSS, Chicago, IL, USA).

Discussion

The results of our research revealed that the effects of short-term air pollution exposure and the incidence of acute myocardial infarction were closely related to the severity of air pollution in the study area. During the study period (2017–2018), poor air quality was indicated on only 7% of the days in the Taoyuan area, whereas in the Taichung area, this percentage was 30%. This result is similar to the finding in our analysis using a health insurance database, and the occurrence of acute myocardial infarction was positively correlated with average air pollution severity in the study area.

Similar findings have been reported in systematic reviews. In low- severity air pollution area, short-term pollutant exposure did not affect the incidence of acute myocardial infarction (Kathrin et al. 2015 ; Janine et al. 2014 ; Ai Milojevic et al. 2014). Studies conducted in moderate- to high-severity air pollution area, which have reported a positive correlation between short-term exposure to pollution and the incidence of acute myocardial infarction (Yongquan et al. 2018 ; Qin et al. 2017 ; Anyang et al. 2017 ; Xiaofang et al. 2016 ; Yisi et al. 2015).

A patient’s chronic health conditions can affect their susceptibility to acute myocardial infarction, but these factors are usually not measured accurately. In 1991, Maclure proposed the case-crossover study design, which is a method for studying transient effects on the risk of acute events (Maclure et al. 1991). Our study employed a 2-week time interval; the air pollution level during the acute myocardial infarction event was compared with the air pollution level 2 weeks before the event. This research method effectively controlled the individual differences between cases.

The mechanism through which long-term exposure to air pollution can lead to cardiovascular disease development has been proven which can increase oxidative stress, the inflammatory response, and vascular endothelial damage, leading to atherosclerosis (A. Seaton et al. 1995 ; Robert et al. 2004 ; Urmila et al. 2002). In cardiovascular disease, atherosclerosis leads to coronary artery stenosis which takes time to accumulate. Long-term exposure to air pollution increase latent cardiovascular diseases and short-term exposure to air pollution can produce oxidative stress and inflammation, increase the burden on the heart then trigger latent cardiovascular diseases. This explains why short-term exposure to air pollutants in areas with severe air pollution increases the risk of acute myocardial infarction.

Our study has three strengths. First, we used medical records from two hospitals, and all patients were identified as having acute myocardial infarction based on records of cardiac catheterization. Second, we could confirm that all patients had been active near the hospital for a long time; thus, the air pollution data from the corresponding monitoring station could represent the patient's exposure to air pollutants. Third, we use the comparison between the day of onset and the day 2 weeks previously to eliminate the effect of changes in patient lifestyle and physical illness.

Nevertheless, our research has two limitations. First, we still could not determine the true air pollution exposure of the patients, which would have been affected by the use of protective equipment or working indoors. Second, we employed medical records from only two hospitals for analysis and research. The results of the study revealed a positive correlation in an area with high-severity air pollution but no correlation in an area with low-severity air pollution. We cannot precisely define a high-severity of air pollution; doing so would require more research data.

Conclusion

The severity of regional air pollution has a serious short-term impact on the risk of acute myocardial infarction. Therefore, to fully prevent acute myocardial infarctions caused by exposure to ambient air pollutants, relevant laws and regulations should be complied with to control the level of ambient air pollutants to the greatest extent possible and thus reduce people’s exposure to air pollutants.

Declarations

Ethical Approval: The present study was approved by the Institutional Review Board of Taipei Medical University and all procedures were accordance with prevailing ethical principles.

Consent to Participate: This study is a retrospective case study. All cases have been treated before data collection and do not involve patient identification. Therefore, patients’ informed consent is not required.

Consent to Publish: Not applicable.

Authors Contributions: Chih-Chien Yen was responsible for study design, acquisition, analysis and interpretation of data, and drafting the manuscript. Ping-Ling Chen contributed to design and interpretation of the analysis and drafting and critical revision of the manuscript. All authors provided approval of the final version of the manuscript and agree to be accountable for all aspects of the work. 

Availability of data and materials: The air pollution data is open providing by the Protection Agency of the Executive Yuan. https://airtw.epa.gov.tw/. The full datasets used in this analysis are available from the corresponding author on reasonable request.

Funding: None.

Acknowledgments: We thank the Taiwan's Air Quality Monitoring Station of the Environmental Protection Agency of the Executive Yuan for providing the air pollution data. The Taoyuan Hospital and Taichung Hospital for providing the medical information. This manuscript was edited by Wallace Academic Editing.

Conflicts of Interest: The authors declare they have no actual or potential competing financial interests.

References

Anyang XuZhe MuBo JiangWei Wang Han Yu Lijuan Zhang, et al., Acute Effects of Particulate Air Pollution on Ischemic Heart Disease Hospitalizations in Shanghai, China. Int J Environ Res Public Health, 2017. 14(2).

Ai Milojevic Paul Wilkinson Ben Armstrong Krishnan Bhaskaran Liam Smeeth Shakoor Hajat , Short-term effects of air pollution on a range of cardiovascular events in England and Wales: case-crossover analysis of the MINAP database, hospital admissions and mortality. Heart, 2014. 100(14): p. 1093-8.

A. Seaton, D. Godden, W. MacNee, K. Donaldson, Particulate air pollution and acute health effects. Lancet, 1995. 345(8943): p. 176-8.

Brook RD, Franklin B, Cascio W, Hong Y, Howard G, Lipsett M, et.al., Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association. Circulation. 2004;109(21):2655. 

Brook RD, Brook JR, Urch B, Vincent R, Rajagopalan S, Silverman F. Inhalation of fine particulate air pollution and ozone causes acute arterial vasoconstriction in healthy adults. Circulation. 2002;105(13):1534. 

Janine WichmannKarin SjöbergLin TangMarie Haeger-EugenssonAnnika RosengrenEva M Andersson, et al., The effect of secondary inorganic aerosols, soot and the geographical origin of air mass on acute myocardial infarction hospitalisations in Gothenburg, Sweden during 1985-2010: a case-crossover study. Environ Health, 2014. 13: p. 61.

Kathrin WolfAlexandra Schneider Susanne Breitner Christa Meisinger Margit Heier Josef Cyrys , et al., Associations between short-term exposure to particulate matter and ultrafine particles and myocardial infarction in Augsburg, Germany. Int J Hyg Environ Health, 2015. 218(6): p. 535-42.

Miller KA, Siscovick DS, Sheppard L, Shepherd K, Sullivan JH, Anderson GL, et.al., Long-term exposure to air pollution and incidence of cardiovascular events in women. N Engl J Med. 2007;356(5):447. 

Maclure, M., The case-crossover design: a method for studying transient effects on the risk of acute events. Am J Epidemiol, 1991. 133(2): p. 144-53.

Pope CA 3rd, Muhlestein JB, May HT, Renlund DG, Anderson JL, Horne BD. Ischemic heart disease events triggered by short-term exposure to fine particulate air pollution. Circulation. 2006;114(23):2443. Epub 2006 Nov 13. 

Pekkanen J, Peters A, Hoek G, Tiittanen P, Brunekreef B, de Hartog J, et. al., Particulate air pollution and risk of ST-segment depression during repeated submaximal exercise tests among subjects with coronary heart disease: the Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air (ULTRA) study. Circulation. 2002;106(8):933. 

Qin Xu, Shuo Wang, Yuming Guo, Chao Wang, Fangfang Huang, Xia Li, et al., Acute exposure to fine particulate matter and cardiovascular hospital emergency room visits in Beijing, China. Environ Pollut, 2017. 220(Pt A): p. 317-327.

Robert D BrookBarry FranklinWayne CascioYuling HongGeorge HowardMichael Lipsett,, et al., Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association. Circulation, 2004. 109(21): p. 2655-71.

Sun Q, Hong X, Wold LE. Cardiovascular effects of ambient particulate air pollution exposure. Circulation. 2010;121(25):2755. 

Urmila P. Kodavanti, Mette C. J. Schladweiler, Allen D. Ledbetter, Russ Hauser, David C. Christiani, James M. Samet, et al., Pulmonary and Systemic Effects of Zinc-Containing Emission Particles in Three Rat Strains: Multiple Exposure Scenarios. Toxicological Sciences, 2002. 70(1): p. 73-85.

World Health Organization (WHO). 2016; Available from: http://www.who.int/mediacentre/factsheets/fs310/en/

Xiaofang Ye, Li Peng, Haidong Kan, Weibing Wang, Fuhai Geng, Zhe Mu, et al., Acute Effects of Particulate Air Pollution on the Incidence of Coronary Heart Disease in Shanghai, China. PLoS One, 2016. 11(3): p. e0151119.

Xie W, Li G, Zhao D, Xie X, Wei Z, Wang W, et.al., Relationship between fine particulate air pollution and ischemic heart disease morbidity and mortality. Heart. 2015;101(4):257. 

Yongquan Yu, Shen Yao, Huibin Dong, Minghui Ji, Zhiyong Chen, Guiying Li, et al., Short-term effects of ambient air pollutants and myocardial infarction in Changzhou, China. Environ Sci Pollut Res Int, 2018. 25(22): p. 22285-22293.

Yisi Liu, Xi Chen, Shuqiong Huang, Liqiao Tian, Yuan’an Lu, Yan Mei, et al., Association between air pollutants and cardiovascular disease mortality in Wuhan, China. Int J Environ Res Public Health, 2015. 12(4): p. 3506-16.

Tables

Table 1 Demographic and medical-related variables of the patients from Taoyuan Hospital.


Acute myocardial infraction


Number

Percentage

Total

352

100.00

Sex

 


Male

269 

76.40 

Female

83 

23.60 

Age

62.90 ± 14.89

Age group (years)

 


<45

42 

11.90 

45-65

157 

44.60 

>65

153 

43.50 

BMI (kg/m2)

 27.51 ± 4.07

<18.5

2.30 

18.5 to <25

128 

36.40 

25 to <30

178 

50.60 

30

38 

10.80 

Hypertension

 


Yes

244 

69.30 

No

108 

30.70 

Hyperlipidemia

 


Yes

65 

18.50 

No

287 

81.50 

Diabetes mellitus

 


Yes

131 

37.20 

No

221 

62.80 

Smoking

 


Yes

229 

65.06 

No

123 

34.94 

Drinking

 


Yes

79 

22.40 

No

273 

77.60 

Heart disease

 


Yes

113 

32.10 

No

239 

67.90 

Family heart disease

 


Yes

76 

21.60 

No

276 

78.40 

 

 

 

Table 2 Demographic and medical-related variables of the patients from Taichung Hospital.


Acute myocardial infraction


Number

Percentage

Total

278

100.00 

Sex

 


Male

199 

71.58 

Female

79 

28.42 

Age

66.16 ± 16.71

Age group (years)

 


<45

 46

16.55 

45-65

 99

35.61 

>65

133 

47.84 

BMI (kg/m2)

 26.18 ± 4.31

<18.5

 3

1.08 

18.5 to <25

 109

39.21

25 to <30

 122

43.88

30

 44

15.83

Hypertension

 


Yes

199

71.58

No

79

28.42

Hyperlipidemia

 


Yes

93

33.45

No

185

66.55

Diabetes mellitus

 


Yes

127

45.68

No

151

54.32

Smoking

 


Yes

187 

67.27 

No

91

 32.73

Drinking

 


Yes

96

34.53

No

182

65.47

Heart disease

 


Yes

83

29.86

No

195

70.14

Family heart disease

 


Yes

67

24.10

No

211

75.90

 

 

 

Table 3 Demographic and medical-related variables of the cases collected from Taoyuan Hospital and Taichung Hospital.

 

Taoyuan Hospital (N = 352)

Taichung Hospital (N = 278)

P

Age, y

62.90 ± 14.89

66.16 ± 16.71

0.51

Male sex, n (%)

269 (76.40)

199 (71.58)

0.44

BMI (kg/m2)

27.51 ± 4.07

26.18 ± 4.31

0.85

Hypertension, n (%)

244 (69.30)

199 (71.58)

0.53

Hyperlipidemia, n (%)

65 (18.50)

93 (33.45)

0.16

Diabetes mellitus, n (%)

131 (37.20)

127 (45.68)

0.43

Smoking, n (%)

229 (65.06)

187 (67.27)

0.62

Drinking, n (%)

79 (22.40)

96 (34.53)

0.27

Heart disease, n (%)

113 (32.10)

83 (29.86)

0.34

Family heart disease, n (%)

76 (21.60)

67 (24.10)

0.55

 

 

Table 4 Incidence of short-term exposure to ambient air pollutants and acute myocardial infarction in the patients from Taoyuan Hospital

Table 4. Poisson regression in the generalized linear model

 

OR

95% CI

95% CI

P

PM2.5

1.006

0.995

1.017

0.315

PM10

0.996

0.988

1.003

0.253

NO2

0.998

0.975

1.021

0.848

SO2

1.051

0.897

1.233

0.536

O3

1.005

0.995

1.014

0.345

OR = odds ratio: adjusted variables listed in the table; CI = confidence interval

 

 

Table 5 Incidence of short-term exposure to ambient air pollutants and acute myocardial infarction in the patients from Taichung Hospital.

Table 5. Poisson regression in the generalized linear model 

 

OR

95% CI

95% CI

P

PM2.5

1.021

1.002

1.040

0.026

PM10

1.010

1.001

1.020

0.035

NO2

0.997

0.988

1.007

0.551

SO2

1.002

0.985

1.021

0.788

O3

1.007

1.000

1.014

0.057

OR = odds ratio: adjusted variables listed in the table; CI = confidence interval