Acute myocardial infarction (AMI)

1. Overview

A heart attack (myocardial infarction [MI]) occurs when one or more areas of the heart muscle do not receive enough oxygen. This results from an obstruction of blood flow to the heart muscle.

2. Causes of a Heart Attack

Blockage of the blood vessels supplying the heart is caused by the buildup of atherosclerotic plaque within the arteries. Plaque is made up of debris, cholesterol, and other substances. When the plaque ruptures, a blood clot rapidly forms. The blood clot is the actual cause of myocardial infarction.

If the blood supply and oxygen to the heart muscle are cut off, heart muscle cells begin to become damaged and undergo necrosis. Irreversible heart muscle damage begins within 30 minutes after the blockage occurs. As a result, the heart muscle affected by oxygen deprivation can no longer function normally.

3. Who Is at Risk of Myocardial Infarction?

Inherited cardiovascular risk factors are risk factors that cannot be changed, but they can be improved through medical management and lifestyle changes.

Acquired risk factors result from an individual's lifestyle and can be managed through lifestyle changes and clinical interventions.

3.1. Genetic Factors: Who Is at the Highest Risk?

The following groups are at the highest risk:

People with hypertension
People with genetically low HDL cholesterol, high LDL cholesterol, or high triglyceride levels
People with a family history of heart disease. This is particularly significant if heart disease developed before the age of 55.
Older men and women
People with type 1 diabetes
Postmenopausal women. In the general population, men tend to develop heart disease at a younger age than women. However, after menopause, women's risk becomes similar to that of men.

3.2. Acquired Risk Factors: Who Is at the Highest Risk?

The following groups are at the highest risk:

People with hypertension
People with low HDL cholesterol, high LDL cholesterol, or high triglyceride levels
Smokers
People experiencing high levels of stress
People who consume excessive amounts of alcohol
People with a sedentary lifestyle
People who are 30% or more overweight
People who consume a diet high in saturated fat
People with type 2 diabetes

A myocardial infarction can happen to anyone. By taking the time to learn about risk factors, you can gain knowledge and take appropriate action to minimize them.

4. Managing the Risk Factors for Myocardial Infarction

The following are ways to control the risk of myocardial infarction:

Identify which risk factors you have, then take steps to eliminate or minimize them.

Learn about high blood pressure and high cholesterol levels. These can be “silent killers.”

Modify non-inherited risk factors by making lifestyle changes. Consult a doctor directly for advice on ways to make these lifestyle changes.

See your doctor for support in managing risk factors that cannot be changed. These may be controlled with medications and lifestyle changes.

5. Preventing Myocardial Infarction

You can help prevent myocardial infarction by knowing the risk factors for coronary artery disease and myocardial infarction and taking action to minimize those risks. Even if you have already experienced a myocardial infarction or are at high risk of having one, you can still reduce your risk by making certain lifestyle changes to improve your health.

Do not smoke. Your doctor may recommend smoking cessation methods, including nicotine replacement therapy.
Eat a diet low in fat, cholesterol, and salt.
Have regular health checkups to monitor blood pressure and cholesterol levels.
Follow a regular program of moderate-intensity exercise. People over 50 who have a sedentary lifestyle should consult a doctor before starting an exercise program.
Lose weight if you are overweight.
Your doctor may recommend regular low-dose aspirin. Aspirin reduces the tendency of the blood to clot and therefore reduces the risk of myocardial infarction. However, such a regimen should only be started under the explicit recommendation of a doctor.
Women who are going through or approaching menopause should discuss the potential cardiovascular benefits of estrogen replacement therapy with their doctor.
Symptoms of a Heart Attack

The following are the most common symptoms of myocardial infarction. However, each person may experience slightly different symptoms.

A feeling of pressure, squeezing, pain, or discomfort in the center of the chest lasting more than a few minutes
Pain or discomfort radiating to the shoulder, neck, arm, or jaw
Chest pain that becomes worse than usual
Chest pain that does not improve with rest or nitroglycerin
Chest pain occurring together with any of the following symptoms:
Sweating, cool extremities, clammy skin, or pallor
Shortness of breath
Nausea or vomiting
Dizziness or fainting
Unexplained weakness or fatigue
Rapid or irregular pulse

Although chest pain is the main warning sign of myocardial infarction, it can be mistaken for other medical conditions, including indigestion, pleurisy, pneumonia, substernal pain, and heartburn.

6. Responding to Warning Signs of Myocardial Infarction

If you or someone you know has any of the warning signs above, act immediately. Call an ambulance right away.

7. Treatment of Myocardial Infarction

The goals of myocardial infarction treatment are to relieve pain, preserve heart muscle function, and prevent death.

Treatment in the emergency department may include:

Medications to relieve chest pain, such as nitroglycerin and morphine
Continuous monitoring of the electrocardiogram and vital signs
Cardiac medications such as beta-blockers to promote blood flow to the heart, improve blood supply, prevent arrhythmias, and reduce heart rate and blood pressure
Thrombolytic therapy: Intravenous administration of medication to dissolve the blood clot and restore blood flow.
Antithrombin or antiplatelet therapy with aspirin or clopidogrel. This is used to prevent further blood clot formation.
Lipid-lowering medications: These medications reduce lipids (fats) in the blood, particularly low-density lipoprotein (LDL) cholesterol. Statins are a class of lipid-lowering medications. Your doctor may prescribe atorvastatin, rosuvastatin, or other statins.

8. You May Need Other Procedures to Restore Blood Flow to the Heart

These procedures are described below:

8.1. Coronary Angioplasty

In this procedure, a balloon-shaped device is inserted into the blood vessel to dilate the narrowed area and increase blood flow. A stent is usually placed at the narrowed site after balloon angioplasty. This procedure is known as percutaneous coronary intervention (PCI), which refers to angioplasty of the coronary arteries. There are several different procedures within PCI:

8.2. Balloon Angioplasty

Coronary artery stenting: A small coil-like device is expanded inside the blocked artery. The stent is left in place to keep the coronary artery open.

Atherectomy: The blocked area inside the coronary artery is drilled or cut away using a small device at the tip of a catheter.

8.3. Coronary Artery Bypass Grafting

Coronary artery bypass grafting (CABG) is generally performed in people with complex coronary artery disease. The surgeon creates a bypass by grafting a segment of a blood vessel above and below the blocked portion of the coronary artery. This allows blood to flow around the blockage. The surgeon usually takes a vein from the leg, but an artery from the chest or arm may also be used. Sometimes, more than one bypass graft is needed to restore blood flow to all areas of the heart.

The information above is for reference purposes only and is not intended as medical advice. Please contact your doctor for detailed medical consultation.