1. Introduction

The widely accepted definition of epidemiology is "the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems" [1]. The overarching aim of epidemiology is to improve the control of disease through both prevention and treatment that will decrease morbidity and mortality due to the disease and will increase the quality of life of those who have a severe illness like coronary artery diseases, e.g., myocardial infarction.

#### 1.1. Coronary heart disease

The most common cause of coronary heart disease (CHD) is atherosclerosis of coronary arteries [2]. Atherosclerosis causes an inadequate supply of oxygen for a given a myocardial demand leading to myocardial hypoxia.

#### 1.2. Atherosclerosis

The sequence of endothelial dysfunction, plaque formation consisting of lipids and smooth muscles, and associated inflammation causes atherosclerotic plaque [3]. Over these plaques rupture and thrombosis causing further narrowing of arteries and occlusion of blood flow can occur.

Although beyond the scope of this chapter, atherosclerosis implies disturbances in the coronary circulation as well as the microcirculation dysfunction.

#### 1.3. Burden of coronary heart disease

Globally, cardiovascular diseases (CVDs) are the number one cause of mortality. According to the World Health Organization (WHO), it is estimated that 7.4 million deaths were due to coronary heart disease in 2015. Eighty-two percent of deaths in low- and middle-income countries are accountable for CVD. Figure 1 shows the age-standardized estimate of mortality by cardiovascular diseases and diabetes per 100,000 people. It is estimated that 23.6 million people will die from CVDs by 2030. These are projected to remain the leading cause of mortality.

#### 1.4. Geographic variations in coronary heart disease

Worldwide the prevalence of CHD is increasing albeit there are regional variations due to the influence of economies, industrialization, and advancement in healthcare systems [5]. Data from the USA suggest about 25% of deaths in the USA are associated with heart disease each year [6]. An American dies due to myocardial infarction (MI) every 60 seconds [6]. The incidence of CHD in the western world is decreasing even though the risk factors for CHD such as hypertension, diabetes mellitus, and obesity are increasing. The decline is due to strengthening healthcare systems due to relative advancement in therapeutic and invasive interventions. As a result, CHD costs the USA about \$200 billion each year [7]. The total cost includes not only the cost of healthcare services or medications, but it also includes the loss of productivity [7].

remains exceptionally high [10]. CVD death rates have been significantly decreasing in most of

Figure 1. Cardiovascular diseases and diabetes, deaths per 100,000 people. Source: Global Health Observatory data

Epidemiology of Myocardial Infarction http://dx.doi.org/10.5772/intechopen.74768 11

The WHO has identified very cost-effective interventions that are feasible to be implemented

The most common form of CHD is the myocardial infarction (MI) [12]. MI occurs when a coronary artery is occluded or almost occluded, which creates a severe reduction in the blood flow, causing some of the heart muscle being supplied by that artery to become infarcted [13].

the countries of Latin America despite the disparities in current trends [11].

even in low resource settings for averting the global epidemic of CVDs.

2. Myocardial infarction

2.1. Defining myocardial infarction

repository and World Health Organization [4].

As Asia comprises over one-third of the world population, its experience on the prevalence of CHD is significant. In India, CHD may not be explained due to the traditional risk factors [8], whereas in China, CHD remains the second most cause of the deaths. Chinese cardiovascular medicine focusses centrally on prevention by shifting its focus from symptom-based therapy to lifestyle-guided improvement [9]. Trends in mortality from CHD were favorable in European Union countries, whereas in Eastern European countries, mortality from CHD

remains exceptionally high [10]. CVD death rates have been significantly decreasing in most of the countries of Latin America despite the disparities in current trends [11].

The WHO has identified very cost-effective interventions that are feasible to be implemented even in low resource settings for averting the global epidemic of CVDs.
