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What is a heart attack?

A heart attack (myocardial infarction) happens when blood stops flowing to part of your heart. Find out about heart attack causes, what you can do to recognise a heart attack and speed your recovery.

coronary artery disease angina heart attack comparison graphic

A heart attack happens when blood stops flowing to part of your heart muscle. Unless blood flow is restored quickly, this can result in permanent heart damage.

If you think someone is having a heart attack, call 111 and ask for an ambulance.

Medical terms for a heart attack may include:

  • myocardial infarction (MI)
  • acute myocardial infarction (AMI)
  • acute coronary syndrome (ACS)
  • coronary thrombosis

These terms refer to changes in the heart muscle (myocardium) due to a lack of blood and oxygen in that area. The main change is death of the heart muscle.

You may also hear the terms:

  • STEMI - A heart attack involving damage to the full thickness of the heart muscle.
  • NSTEMI - A heart attack that doesn’t involve the full thickness of the heart muscle.


Find out what can cause heart attack and learn some of the common names for the condition.

Blood flows to your heart through the coronary arteries. A blockage in one of your coronary arteries can cause a heart attack.

Coronary artery disease (also called atherosclerosis) is a common cause of a heart attack. This is when deposits of fat and other substances build up in the inner lining of an artery. This build-up is called atheroma or plaque. If one of the plaques crack, a blood clot will form which can block the artery and cause a heart attack.

A less common cause of heart attack is spontaneous coronary artery dissection (SCAD), a condition where one or more of the coronary arteries tear.

Family history

There is a lot we don’t understand about what contributes to causing a heart attack, but people who have a family history of heart attack or heart disease are more likely to have a heart attack themselves.

If you are aged under 50 when you have your heart attack, your immediate relatives are at greater risk of developing heart disease.

Read about changes you can make to lower your risk of having a heart attack.


Heart attack warning signs can include heaviness, tightness, pressure, discomfort or pain in your chest, shoulder, jaw, arm, neck, mid-back, sometimes accompanied by sweating, shortness of breath, nausea, fatigue, or dizziness.

It is possible to have a 'silent' heart attack, where you do not experience pain or where the only warning sign may be an indigestion type of discomfort. This is most common in women or people with diabetes. It is medically referred to as silent ischemia (lack of oxygen) to the heart muscle.

Learn more about heart attack warning signs.

Heart attack symptoms in women

Women may have different heart attack symptoms than men. This is possibly because women are more likely to have blockages, not only in their main coronary arteries, but also in the tiny coronary artery blood vessels that branch off from the main ones. This is called microvascular coronary disease.

Heart attack symptoms can be subtle in women, which is why it's important to know what to look out for.

Learn more about heart attacks in women.


While having a heart attack, your heart doesn't look or work like it normally would. Common heart tests used to identify these changes include:

  • An electrocardiograph (ECG) test shows any changes in the electrical activity of your heart. More about electrocardiography
  • Blood tests can show higher levels of certain proteins or enzymes made during a heart attack
  • An echocardiogram uses soundwaves to show any changes to the structure, function and size of your heart
  • An angiography is when contrast dye is used to make x-ray pictures of your coronary arteries, the ones leading to your heart. This test shows both how bad and where any blockage is, information that is used to decide whether to do a stent or coronary artery bypass graft surgery.


Early treatment to restore blood flow to the heart muscle can prevent or limit the amount of damage.

Common treatments for a heart attack can include a stent or coronary artery bypass graft surgery or thrombolysis.

Cardiac arrest or heart attack?

A heart attack is not the same as a cardiac arrest. They are two different types of cardiac event.

A heart attack occurs when a coronary artery becomes blocked, preventing blood flow to part of the heart muscle. During a heart attack a person remains conscious and keeps breathing.

A cardiac arrest occurs when the heart stops pumping blood around the body. Normal breathing stops and consciousness is lost. 

Sometimes a heart attack can cause a cardiac arrest. This is because a person who is having a heart attack may develop a dangerous heart rhythm, which causes a cardiac arrest. A heart attack and a cardiac arrest are both emergency situations. Call 111 straight away. 


Had a heart attack? Find out what to expect next.

Recovery after a heart attack