Myocardial infarction (MI), commonly known as heart attack, results when there is necrosis or irreversible death of heart muscle due to lack of oxygen to that muscle. Lack of oxygen occurs when there is an imbalance in the demand and supply of oxygen. The oxygen supply is interrupted as the coronary arteries are narrowed due to plaque rupture and thrombus formation.
The severity of MI or heart attack depends upon the duration and extent of ischemia (lack of oxygen) and the type of heart muscle involved. It is one of the leading causes of death in the world. In the United States alone, there are 1.5 million cases of myocardial infarction reported per year.
The majority of cases of MI are caused by atherosclerosis. Atherosclerosis is defined as the thickening of the vessel wall due to the build-up of cholesterol inside the lumen. The build-up can form plaque that ruptures and obstructs the lumen of the entire vessel. Atherosclerosis can be caused by various reasons such as high cholesterol levels in the body, high blood pressure, etc.
Nonatherosclerotic causes are the conditions or diseases that involve coronary vessels or cardiac muscles. These include certain drugs, myocarditis, coronary trauma, etc.
MI can be divided into several types depending upon the underlying cause:
Another classification is based on the types of acute coronary syndromes in which there is a sudden loss of oxygen supply to the cardiac muscle resulting in ischemia or necrosis. These types include:
Myocardial infarction is prevalent worldwide. It is one of the leading causes of death worldwide. In the United States, one-third of all deaths in the population older than 35 are due to MI.
Mortality associated with MI has decreased significantly due to better lifestyle choices, health-seeking behaviors, and education about the disease.
Risk factors for MI include:
Following are the signs and symptoms of myocardial infarction:
Complications of MI include:
An ECG makes the diagnosis of myocardial infarction. In more than 80 percent of cases, it is confirmatory. Diagnosis is aided by specific laboratory tests that also help manage MI. These include:
Differential diagnoses of MI include:
Once the patient is hospitalized, the initial management is continued with additional therapy that includes:
The prognosis of myocardial infarction depends upon the time elapsed between the episode and treatment. It is associated with 30% mortality, and almost 50% of deaths occur before bringing them to the hospital.
If reperfusion treatment is started within 6 hours of the onset of MI, the prognosis is usually good, depending upon other factors such as comorbidities, age, and weight. When performed within 6 hours of the onset of MI, revascularization procedures can be most beneficial, preventing remodeling of the heart muscle and other associated complications.
Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 25, 2023.
Heart failure after myocardial infarction: incidence and predictors - Jenča - 2021 - ESC Heart Failure - Wiley Online Library
Myocardial Infarction - StatPearls - NCBI Bookshelf (nih.gov)