Current Status of Myocardial Infarction and Risk Factors for Associated Mortality in Iran : A Review

1Department of Epidemiology and Biostatistics, School of Health, Modeling in Non Communicable Disease Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran 2Department of Epidemiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3Company of Advanced Health Research Technology, Incubator Center of Health Technology, Shahrekord University of Medical Sciences, Shahrekord, Iran 4Cardiologist, Department of Cardiology, Hajar Hospital, Modeling in Non Communicable Disease Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran Received date: 21 Dec 2015; Accepted date: 21 Jan 2016; Published date: 27 Jan 2016.


Introduction
Cardiovascular diseases are considered one of important priorities in health system worldwide, including Iran.The burden of these diseases is increasing in low-, moderate-, and high-income countries.High prevalence and incidence of myocardial infarction (MI) as the most important cardiovascular disease and reason for death has no geographical, spatial, gender, and social limit [1,2].
Mortality rate per 100,000 population due to these diseases is 265 worldwide, 224 in Eastern Mediterranean, and 171 in Iran [2,3].By 2020, cardiovascular disease-associated mortalities will increase by 15% in developed countries, 77% in China, and 106% in other Asian countries.Finland and Japan have the highest and lowest MI incidence rate in the world, respectively [3][4][5].
Initially, the keywords "Epidemiologic/myocardial infarction/Mortality/ analysis" [Mesh] AND "Epidemiologic/ Risk Factor/ Iran" were selected in valid and reliable database.Then, reliable databases were searched for relevant publications.Being relevant, containing viewpoints, and recommending statistical guidelines as well as approval of at least two of the three examiners of articles were determined as the inclusion criteria into the study.In addition to the articles published by other authors, all the articles authored by the first author of this review article and obtained from the studies in which the data of Iranian Myocardial Infarction Registry (IMIR) were used were also included.Therefore the IMIR will be introduced and the methods adopted to analyze its data will be briefly explained in the following section.IMIR is present in all hospitals equipped with a cardiac care unit in 31 provinces of Iran.Inclusion criteria were based on World Health Organization (WHO) and World Heart Federation (WHF) definition of MI by International Classification of Diseases (ICD: I22, I21) [6,17].The patients with MI history or non definite diagnosis made by cardiologist were excluded from the study.The data on age, gender, and the province of residence were collected.

Results
The findings are presented in two sections: The first section is related to the published articles summarized in table 1 and the second section addresses the data of 20750 MI patients obtained from IMIR as follows: 15033 (72.4%) patients were male.The mean (SD) age of the patients was 61.2 ± 13.4 years.The mean age at MI incidence was significantly lower in men (59.6 ± 13.3 years) than women (65 ± 12.6 years) (P=0.001).The mean age at MI incidence was significantly different by place or the province of residence (P=0.001).The age of over 84 years, being female, educational level, smoking, lack of thrombolytic therapy, type 2 diabetes, chest pain prior to arriving in hospital, right bundle branch block (RBBB), ventricular tachycardia (VT), percutaneous coronary intervention (PCI), lateral MIs, and ST-segment elevation myocardial infarction (STEMI) were present.Individual risk factors had independent effects on the hospital mortality due to MI. Variables in the province level had no significant effect on the outcome of MI.Enhancing access to and quality of treatment especially in the individuals at MI risk could reduce the mortality due to MI. MI incidence was clustering in six provinces (North Khorasan, Yazd, Kerman, Semnan, Golestan and Mazandaran).In-hospital case fatality rate (CFR) was 12.1% (n=2511).Women/men rate ratio of fatality was 1.36 (95% CI: 1.2-1.4).In-hospital CFR was 8.36 (7.81-8.94) in women and 6.12 (5.83-6.43) in men.Hazard ratio of mortality for STEMI, chest pain resistant to treatment, and RBBB was respectively 2.88, 2.55, and 2.06.Use of PCI was reported to decrease the risk of death in patients (hazard ratio: 0.68).83.7% of the patients with STEMI died.

Discussion
In this study, epidemiological status of MI incidence and the risk factors for associated mortality were reported for the first time in Iran through a review study.The age of over 84 years, being female, educational level, smoking, lack of thrombolytic therapy, type 2 diabetes, chest pain prior to arriving in hospital, RBBB, VT, PCI, lateral MIs, and STEMI were increase Mortality rate of MI patents in Iran.The results of this review article could offer an appropriate opportunity to management, evidencebased decision making, and planning for the prevention and control of MI and associated mortality in Iran.Although cardiovascular diseases have been decreasing in developed and high-income countries, this trend is on rise in developing and moderate-and low-income countries, such as Iran [3,[13][14][15].According to the Iranian Mortality Registry, the mortality rate due to cardiovascular diseases and MI was reported respectively 171 and 85 per 100,000 population.In our study, mortality rate due to MI was 6.74.The mortality rate in Iran is lower compared to those of Eastern Mediterranean and worldwide [11].The main reason for this difference seems to be the ways of accessing and receiving healthcare, variety of risk factors worldwide, and Iran's young population.To compare the determinants of in-hospital mortality risk with those investigated in other studies, to the best of our knowledge no similar study in Iran's neighboring countries has been yet conducted.In our study, a difference in the age at MI incidence was noted between men and women, which is consistent with other studies.The age over 84 years was yielded as the risk factor for death, in agreement with the works in other countries, such as Japan and Korea [4,[16][17][18].
The incidence rate in our study was higher compared to Japan and Korea and lower compared to Finland and Australia.In-hospital mortality rate was higher in women compared to men in Japan.In-hospital mortality rate was lower in the patients in Iran compared to Japan [3,4].In Korea, 19.2% of MI patients had diabetes, 67.3% were smoker, and 61.2% had STEMI.In our study, the prevalence of diabetes was 22.2%, which is higher compared to Japan.In our study, hypertension association with in-hospital mortality was significant (P=0.011,OR=1.11) in univarite analysis, but it was non significant in multivariate analysis.In Japan, hypertension was significantly associated with the patients' mortality [18].
In a study, age, being female, lack of thrombolytic therapy, and STEMI were the most determinants of survival and mortality in the MI patients, which is similar to our study.Hypertension, type 2diabetes, and smoking were obtained as respectively 49%, 53%, and 30% in multiple regressions and were not significant as risk factor for death [19].In a study, 73% of the patients were male and their mean age 61.8 years, which is similar to our study.History of coronary artery bypass grafting, PCI, and diabetes were reported respectively 4.4%, 12.5%, and 25.3% in the patients; these rates were obtained respectively 2.6, 3.2, and 22.2% in our study, which are lower compared to that study [20].In our study, in-hospital mortality rate due to MI was 12%, which is lower compared to 23.3% reported by another study [11].In a study in India, the mean age of the patients was reported 57.5 years, which is lower compared to Iran.In India, 30.4% of the patients had type 2 diabetes and 37.7% hypertension, and 40% were smoker; the corresponding figures in our study were respectively 22.2%, 35.5%, and 26.2%.In India, despite the high prevalence of risk factors, the death percentage was 6.7%, which is lower compared to our study.In our study, 83% of the patients were hospitalized for less than six days.In India, this figure was obtained 57.3%.The difference in mortality percentage between our study and the study in India could be due to difference in patterns of and access to treatment as well as approaches to offering healthcare services [21][22][23].In-hospital mortality due to MI in the USA was higher in blacks compared to whites and higher in the individuals over 70 years compared to other ages.This rate was reported 10-70% [24][25][26][27][28].The difference in incidence rate, mortality, and the factors associated with in-hospital mortality, and the mean age could be due to old population of some countries, like the USA and Japan, the difference in life expectancy and lifestyle, the difference in distribution of and coping with cardiovascular diseases risk factors, and the approach to offering healthcare.Failure to follow up the patients for 28 days, to include MI death cases outside hospital and home and to calculate the patients' survival time were some of the limitations of the present study, which should be addressed in the future studies.

Conclusion
STEMI and age over 84 years are likely to contribute mostly to in-hospital mortality in the patients with MI.The findings of the present study could be useful in planning in health system, monitoring, and improving the patients' care and treatment.The individual variables had a determining effect on the mortality due to MI.So, individual interventions in healthcare centers, clinics, and community at large for lifestyle changes contribute importantly to preventing and controlling mortality.Less importantly, the

Forschen Sci
O p e n H U B f o r S c i e n t i f i c R e s e a r c h Citation: Ahmadi  Open Access 4 variables related to the living environment such as temperature, relative humidity, and precipitation may determine the mortality in patients.
Variables at the province level had no significant effect on the outcome of MI.Implementing educational strategies, motivating people to refer physicians early, and increasing access to treatment especially for the individuals at MI risk could reduce the mortality due to MI.  Open Access n H U B f o r S c i e n t i f i c R e s e a r c h Citation: Ahmadi A, Etemad K, Ahmadi S, Khaledifard A (2016) Current Status of Myocardial Infarction and Risk Factors for Associated Mortality in Iran: A Review.J Epidemiol Public Health Rev 1(1): doi http://dx.doi.org/10.16966/2471-8211.104 Citation: Ahmadi A, Etemad K, Ahmadi S, Khaledifard A (2016) Current Status of Myocardial Infarction and Risk Factors for Associated Mortality in Iran: A Review.J Epidemiol Public Health Rev 1(1): doi http://dx.doi.org/10.16966/2471-8211.104 A, Etemad K, Ahmadi S, Khaledifard A (2016) Current Status of Myocardial Infarction and Risk Factors for Associated Mortality in Iran: A Review.J Epidemiol Public Health Rev 1(1): doi http://dx.doi.org/10.16966/2471-8211.104