Myocardial Infarction Overview

A myocardial infarction occurs when blood flow through the coronary arteries to the myocardium decreases or stops completely. Deprived of the oxygen carried by the blood, myocardial cells begin to die.¹ Data from the National Heart, Lung, and Blood Institute’s (NHLBI) Atherosclerosis Risk in Communities study suggest that more than 800,000 people in the United States experience myocardial infarction each year.²

The leading cause of myocardial infarction is coronary artery disease, but myocardial infarctions can also occur in the absence of obstructive coronary artery disease. Women are more likely than men to experience these types of myocardial infarctions, especially during pregnancy and postpartum.³ Other factors, such as hypertension, obesity, smoking, and stress, can increase the risk of a myocardial infarction in both women and men, but the increase in risk is often greater among women.⁴ Research has also found that women with diabetes have a substantially increased risk of fatal coronary heart disease, including myocardial infarction, when compared to men with diabetes.

Pressure or pain in the chest are the most recognizable symptoms of a myocardial infarction.⁵ However, women are more likely than men to have other symptoms, including shortness of breath; nausea; extreme fatigue; and pain in the back, neck, jaw, or shoulders.^{4 , 6 , 7} These symptoms may occur in the absence of chest pain, which means women may have difficulty recognizing them as the symptoms of a myocardial infarction and may not seek medical attention.⁴

Treatment for acute myocardial infarction will vary depending on whether a person is experiencing a ST-segment elevation myocardial infarction (STEMI) or non–ST-segment elevation myocardial infarction (NSTEMI); the goal in both cases is to restore normal blood flow to the heart, usually through the use of medications (e.g., thrombolytics) or nonsurgical procedures (e.g., percutaneous coronary intervention [PCI]). Cardiac rehabilitation has been shown to improve quality of life and decrease mortality rates after myocardial infarction, making it an important component of recovery.⁷ However, when compared with men, women are significantly less likely to be referred to a cardiac rehabilitation program, less likely to enroll, and less likely to complete a program.^{8 , 9} The barriers that may be preventing women from participating in cardiac rehabilitation are still being investigated. Other areas of active research include nonobstructive causes of myocardial infarction in women and the specific risks that factors such as hypertension, smoking and vaping, chronic stress, and pre-eclampsia confer in women.

A study supported by the National Institute on Aging (NIA) reviewed data from more than 1.5 million adults aged 66 years and older who were hospitalized with STEMI or NSTEMI between 2011 and 2018. These data represented patients from multiple countries, including the United States. The researchers reported that hospitalization rates declined for both men and women during this period across all the countries. However, they found that women with STEMI were less likely to receive certain treatments, such as PCI and coronary artery bypass graft surgery, than men. Women with STEMI also had higher mortality rates than men with the same condition in five out of the six countries in the study.¹⁰

NHLBI is a major supporter of research on the diagnosis, treatment, and prevention of heart and vascular diseases. One NHLBI-sponsored research study, the Multi-Ethnic Study of Atherosclerosis (MESA), is working to identify the characteristics of subclinical cardiovascular disease and the risk factors that may lead to disease progression. Since the study began, it has recruited participants across the United States and evaluated the occurrence of any cardiovascular disease events, including myocardial infarction. MESA aims to identify the potential contributing factors for cardiovascular disease, including those that do not have obvious symptoms.¹¹