What is a Heart Attack?

A heart attack is scary. If you’ve had one, or are close to someone who has, you’re not alone. Many people survive a heart attack and go on to enjoy productive lives.

The following details can help you understand what’s happened and how your heart can heal. Use this information to help you live a healthier, longer life.

See how coronary artery damage leads to a heart attack. 

What happens during a heart attack?

Your heart muscle needs oxygen to survive. A heart attack occurs when the blood flow that brings oxygen to the heart is reduced or cut off. If blood flow is reduced or stopped for too long, the heart muscle begins to die

View an animation of blood flow between the heart and lungs.

This happens when coronary arteries that supply the heart muscle with blood flow become narrowed from plaque — a buildup of fat, cholesterol and other substances.

This slow process is known as atherosclerosis.

When plaque within a heart artery breaks, a blood clot forms around the plaque. This blood clot can block blood flow through the artery to the heart muscle.

About every 40 seconds, someone in the United States has a heart attack.  

Why didn’t I have any warning?

Atherosclerosis may have no symptoms in its early stages. But when an artery is narrowed by over 70%, there may be muscle pain or cramps. This happens because the surrounding tissue needs more oxygen than it’s able to receive.

When a coronary artery narrows and constricts blood flow, other nearby blood vessels sometimes expand to help. This could explain why there may be no warning signs.

This network of expanded blood vessels is called collateral circulation. It helps protect some people from heart attacks by delivering needed blood to the heart. Collateral circulation can also develop after a heart attack to help the heart muscle recover.

Is my heart permanently damaged?

When a heart attack occurs, the heart muscle that has lost blood supply begins to suffer injury. It begins to die if blood supply is not restored. The amount of damage to the heart muscle depends on:

• The size of the area supplied by the blocked artery
• The time between injury and treatment

Heart muscle damaged by a heart attack heals by forming scar tissue. It usually takes several weeks for your heart muscle to heal. The length of time depends on:

• The extent of your injury
• Your rate of healing

The heart is a tough organ. Even if part of it has been injured, the rest of the heart keeps working. Still, your heart may be weakened and unable to pump as much blood as usual.

With treatment and lifestyle changes, further damage can be limited or prevented.

Learn more about heart damage detection.

How long will it take to recover from my heart attack?

Talk to your health care professional about your recovery time. Heart attacks can have longer or shorter recoveries and complications. This depends on the size and location of the damage and the treatment you receive. Scar tissue may form in the damaged area. Scar tissue doesn’t contract or pump as well as healthy muscle tissue. The amount of damage to the heart muscle can affect how well the heart pumps blood.

How much pumping function is lost depends on the size and location of the scar tissue. Most heart attack survivors have some kind of coronary artery disease. They will have to make lifestyle changes and possibly take medication to prevent a future heart attack. Surgeries or cardiac rehab may also be needed to help with recovery. Taking these steps can help you lead a full, productive life.

Learn more about recovering from heart attack.

Is all chest pain a heart attack?

No. But if you have chest pain or discomfort, see a health care professional right away. A common type of chest pain is angina. It’s a recurring discomfort that often lasts only a few minutes. Angina occurs when your heart muscle doesn’t get the blood supply and oxygen it needs. Angina is a sign that you’re at higher risk of having a heart attack.

Angina attacks don’t permanently damage the heart muscle.

Different types of angina include:

• Stable angina, or angina pectoris. It often occurs during exercise or emotional stress when:
  • Your heart rate and blood pressure increase
  • Your heart muscle needs more oxygen.

  Learn more about stable angina.
  

• Unstable angina. Unstable angina occurs while you’re resting or sleeping. It comes as a surprise. Unstable angina can lead to a heart attack. It should be treated as an emergency. Learn more about unstable angina.

What are other medical terms for a heart attack?

Myocardial infarction (MI): When an area of the heart muscle is damaged or dies after blood supply is blocked. MI is the classic medical term for a heart attack.

Acute coronary syndrome (ACS): When the blood supplied to the heart muscle is suddenly blocked. Learn more about ACS.

STEMI: STEMI is a common name for ST-elevation myocardial infarction. It’s caused by a complete blockage in a coronary artery.

NSTEMI: A non-ST-elevation myocardial infarction is when an artery is partially blocked and blood flow is greatly reduced. 

Coronary thrombosis: When a clot forms in one of the arteries that supply blood to the heart muscle. This slows or blocks blood flow to part of the heart muscle and can cause a heart attack. It’s also called coronary occlusion. 

Are there other causes of heart attack besides blockage?

Sometimes a coronary artery temporarily contracts or  spasms. When this happens, the artery narrows, and blood flow to part of the heart muscle decreases or stops.

A spasm can occur in  normal blood vessels and vessels partly blocked by plaque. A severe spasm can cause a heart attack.

Another rare cause of heart attack is spontaneous coronary artery dissection (SCAD). This is a sudden tearing of the coronary artery wall.

How is a heart attack different from cardiac arrest?

People often use these terms to mean the same thing, but they are different events.

A heart attack is when blood flow to the heart is blocked. It’s a circulation problem.

With sudden cardiac arrest, the heart malfunctions and suddenly stops beating. Sudden cardiac arrest is an electrical problem caused by irregular heart rhythms, also called arrhythmias. A common and potentially deadly arrhythmia is ventricular fibrillation. This happens when the heart’s lower chambers start beating chaotically and don’t pump blood.

A heart attack can cause ventricular fibrillation, which can cause sudden cardiac arrest. Death can happen within minutes after the heart stops.

Cardiac arrest may be reversed if both:

• CPR is performed
• A defibrillator is used within minutes to shock the heart and restore a normal heart rhythm.

Learn more about the differences between heart attack and cardiac arrest. 

You aren’t alone

Connect with other heart attack survivors and caregivers through our Support Network.

Learn more about diseases and conditions that affect your heart.