What Is a Heart Attack?

A heart attack—or myocardial infarction—occurs when the oxygen-rich blood flowing to your heart muscle is blocked. If this blood flow is not restored, your heart will begin to die without oxygen.

Symptoms of a heart attack may vary from person to person, but commonly include chest pain, trouble breathing, dizziness, and pain in your arm or jaw.

Each year in the United States, nearly 805,000 people have a heart attack. Of this number, about 200,000 have had a heart attack in the past. It's estimated about 1 in 5 heart attacks are silent, meaning damage has been done to the heart without any noticeable symptoms.

Typically, heart attacks are caused by coronary artery disease, which can cause plaque to build up in your arteries. However, other issues like heart spasms or a blood clot can lead to a heart attack. Fortunately, many people survive a heart attack and live full lives afterward, but getting prompt medical treatment is key.

Types of Heart Attack

When most people think of a heart attack, they have images of someone clutching their chest. But there are actually three primary types of heart attack, some of which can occur in a slightly less intense manner.

ST-Elevation Myocardial Infarction (STEMI)

The most life-threatening heart attack is the STEMI, which occurs when there is a total or nearly total blockage of a coronary artery. Since these arteries supply oxygen-rich blood to your heart muscle, their blockage can deprive your heart of blood and oxygen leading it to fail.

STEMI are often caused by an atherosclerotic plaque rupture, which is when plaque formed by a buildup of cholesterol and fats bursts and blocks the artery.

Non-ST-Elevation Myocardial Infarction (NSTEMI)

An NSTEMI occurs when your heart's need for oxygen cannot be met. Unlike the STEMI, it does not have an easily identifiable electrical pattern (or ST-elevation). This means it won't appear as a spike on an echocardiogram (ECG), a common test for suspected heart attacks.

NSTEMI heart attacks happen because of a partial blockage in the coronary artery or blockage in a branch off of the coronary artery. These types of heart attacks are life-threatening and require immediate medical care. Of the people who experience a heart attack each year, 70% will have a NSTEMI.

Coronary Spasm

A coronary spasm is a temporary constriction of an artery in your heart. The spasm can slow or stop blood flow through your artery which causes chest pain (angina). These spasms are most common in people who smoke or who have high cholesterol or high blood pressure. They can be triggered by emotional stress, exposure to cold, alcohol withdrawal, and certain medications.

Heart Attack Symptoms 

Knowing the symptoms of a heart attack and acting quickly can improve the chances of surviving the event. Typically, heart attacks involve discomfort in the center or left side of the chest. This might feel like an uncomfortable pressure, squeezing, fullness, or pain.

The primary symptoms of a heart attack include:

• Experiencing chest pain or discomfort
• Feeling weak, lightheaded, or faint
• Having pain or discomfort in the jaw, neck, back, arms, or shoulders
• Being short of breath
• Feeling unusually tired
• Vomiting or feeling nauseous

If you or someone you are with experiences any of these symptoms, call 911 for emergency medical care right away.

What Causes a Heart Attack? 

In most cases, a heart attack is caused by coronary artery disease, which occurs when the artery cannot get enough oxygen-rich blood to the heart. Coronary artery disease can occur as a result of atherosclerosis, which is a build up of plaque inside the arteries that causes the arteries to become more narrow.

As the disease progresses, an area of plaque can break open (rupture) inside the artery, which causes a blood clot to form. If the clot becomes too large, it can block blood flow to your heart and cause a heart attack.

However, not all heart attacks are caused by coronary artery disease. When other conditions cause a heart attack, this is called myocardial infarction in the absence of obstructive coronary artery disease (MINOCA). Some of the conditions that can cause MINOCA include:

• Embolism, or when a blood clot or air bubble causes a sudden block of the artery
• Spasm of the coronary artery, which can tighten the artery and block blood flow
• Small plaques, which can break open and cause blood clots
• Spontaneous coronary artery dissection (SCAD), which occurs from a tear in the artery that can block the artery or cause a blood clot to form

Risk Factors

There are certain factors that increase the likelihood of having a heart attack. Some of these factors are based in genetics while others stem from lifestyle and can be managed.

You may be at a higher risk for a heart attack if you:

• Eat a high sodium diet
• Lack regular physical activity
• Smoke
• Have high cholesterol or high blood triglycerides
• Have been diagnosed with high blood pressure or preeclampsia
• Have high blood sugar or have been diagnosed with diabetes
• Are overweight or have obesity
• Are over the age 45 (for men) or over the age 55 or have gone through menopause (for women)
• Have a family history of early heart disease
• Have contracted an infection from bacteria and viruses

How Is a Heart Attack Diagnosed?  

Once you arrive at the hospital, a healthcare provider will perform several tests to determine whether you are currently having a heart attack or if you already had one. These tests might include:

• Electrocardiogram: Typically, the first test a healthcare provider will use in diagnosing a heart attack is an electrocardiogram (ECG or EKG), which measures the electrical activity in your heart.
• Blood tests: When cells in your heart muscle die, they release proteins into your bloodstream. For instance, you may get a troponin test to determine if any of this protein—which is usually only in the heart—has leaked into your blood. While there are a number of other blood tests that can be ordered, this test is often preferred.
• Imaging: Tests such as a chest x-ray or CT scan may be used to determine whether your heart is working properly.
• Stress test: During a stress test, you will perform light exercise or receive medication to simulate exercise on the heart. A healthcare provider will perform an EKG and measure your blood pressure while this is happening. This can help determine the cause of the heart attack and the amount of damage to your heart.

Treatments for a Heart Attack  

When you have a heart attack, your medical team may start emergency treatment before diagnosis. Early treatment can limit damage to your heart, help it work better, and improve your chances for survival.

Medications

During a heart attack, certain medications can help break up any blood clots and allow your heart to function better. These include:

• Thrombolytic medicines: Also known as clot busters, these medications help dissolve blood clots blocking your coronary arteries.
• Nitroglycerin: This medication can improve blood flow and reduce chest pain.
• Aspirin: This medication is sometimes administered to keep other blood clots from forming.

Procedures and Therapies

If you are having or have had a recent heart attack, you may undergo certain procedures to help you survive. Common treatments used during a heart attack include:

• Oxygen therapy: This treatment involves administering oxygen to improve breathing and blood oxygen levels.
• Percutaneous coronary intervention (PCI): This procedure, which is also called coronary angioplasty, is a nonsurgical procedure that opens narrowed or blocked blood vessels to the heart using a catheter and live x-rays. This improves blood flow to the heart.
• Stenting: A stent is a small mesh tube that can hold open weak or narrow arteries.
• Coronary artery bypass grafting: This procedure improves blood flow to the heart and may be needed if the coronary arteries are narrowed or blocked.

How to Prevent a Heart Attack 

Whether you've already had a heart attack or are at high risk for one, there are ways to lower your risk of a heart attack. Start by talking to a healthcare provider about managing your heart health and any other conditions that increase your risk, including high blood pressure, cholesterol, and diabetes.

With a healthcare provider's direction, try to get plenty of physical activity. Being physically active after your first heart attack can help prevent a second one. Research has found people who were physically active had a 34% lower risk of having a second heart attack compared with people who did not exercise.

People who were physically active specifically during the first year after a heart attack had a 63% lower chance of having a heart attack when compared with people in the least active group. 

You can also improve your heart health and reduce your risk for a heart attack by:

• Preparing meals that are low in sodium and have plenty of fruits and vegetables.
• Taking your medications as recommended and attending your medical appointments.
• Prioritizing your sleep, aiming for seven to eight hours a night.
• Managing your stress through strategies like meditation, a warm bath, journaling, or quiet time with a good book.
• Talking to a healthcare provider to determine if weight management is right for you.

Related Conditions   

There are some medical conditions that can increase your risk of having a heart attack. While these conditions do not necessarily cause your heart attack, the impact they have on your blood vessels increase your risk. Common comorbid conditions include:

• Metabolic diseases: Metabolic diseases such as diabetes, hypertension, and dyslipidemia have been reported in more than half of people that had a heart attack. Research indicates adults with diabetes are nearly twice as likely to have heart disease—which can lead to heart attack—than people without the condition.
• Cancer: If you are diagnosed with cancer, this can increase your risk of a heart attack or stroke. Some research suggests the risk of heart attack and stroke may even be doubled within six months of a cancer diagnosis.
• Chronic kidney disease: People with chronic kidney disease (CKD) have an increased risk of heart attack as well as coronary artery disease, arrhythmias, and heart failure. People with advanced CKD have an elevated risk, with heart attacks accounting for 40% to 50% of deaths.

Research indicates there may be a number of other comorbidities associated with heart attack. These include epilepsy, heart failure, stroke, alcoholism, asthma, psychiatric diseases, and rheumatoid arthritis, among others.

Living Well After a Heart Attack  

Having a heart attack may impact the strength and function of your heart, putting you at risk for other cardiovascular conditions like stroke. Depending on the damage done to your heart, you may be able to return to your normal activities within a few weeks.

In some cases, your healthcare provider may refer you to a cardiac rehabilitation program. These outpatient programs are designed to help you recover after a heart attack with the guidance of medical professionals. Over the course of a few months, you will receive exercise education, counseling to reduce stress, and guidance on a heart-healthy diet—all of which play an instrumental role in your recovery.

Many people live a long and healthy life after having a heart attack. It's important to follow your healthcare provider's instructions and make prevention of a second heart attack a priority. You can manage your risk factors by taking your medications, getting physically active, and following a nutritious, heart-healthy diet.