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Heart attack | Hē manawa

Also known as a myocardial infarction (MI)

Key points about heart attack (hē manawa)

Heart attack occurs when blood flow to a section of heart muscle becomes blocked.
If the flow of blood isn’t returned quickly, the section of heart muscle becomes damaged from lack of oxygen and starts to die.
Heart attack symptoms vary. Some are sudden and intense but most start slowly, with mild pain or discomfort that can be easily mistaken for indigestion.
If you have severe chest pain for more than 15 minutes, assume it's a heart attack.
A heart attack is a medical emergency and you need immediate medical help.

Animation of man clutching chest in pain

Symptoms of heart attack vary. However, if you have severe chest pain for more than 15 minutes, assume it's a heart attack, and do the following:
Call 111, ask for the ambulance service and tell them you are having a possible heart attack. If available, chew one aspirin, unless you have been previously advised not to take aspirin. Rest quietly and wait for the ambulance. Get someone to wait with you, if possible. Remaining calm means you are less likely to suffer some of the heartbeat disturbances that create problems for you and your immediate medical advisors.

Symptoms of heart attack vary. However, if you have severe chest pain for more than 15 minutes, assume it's a heart attack, and do the following:

Call 111, ask for the ambulance service and tell them you are having a possible heart attack.
If available, chew one aspirin, unless you have been previously advised not to take aspirin.
Rest quietly and wait for the ambulance.
Get someone to wait with you, if possible.
Remaining calm means you are less likely to suffer some of the heartbeat disturbances that create problems for you and your immediate medical advisors.

Some heart attacks are sudden and intense but most heart attacks start slowly, with mild pain or discomfort that can be easily mistaken for indigestion. Symptoms often differ between men and women. Often an attack is triggered by some form of exercise or heavy work but this is not always the case.

Chest pain/discomfort

If you have chest pain that lasts more than a few minutes it may be a sign of a heart attack.

The pain may:

initially come and go
be in one or both arms (more commonly the left)
go into your neck, back, jaw, stomach and abdomen
also feel like squeezing, pressing, tightness or fullness.

Symptoms in women

Chest discomfort may not be the worst, or most noticeable, symptom in women. Women are more likely than men to experience the following symptoms, with or without chest discomfort:

sweating
feeling faint
feeling sick
vomiting
being short of breath
palpitations (a noticeably fast, strong or irregular heartbeat).

You may not experience all of these symptoms. If you are experiencing some of them call 111 without delay. See also why women ignore heart attack symptoms.

(Heart Foundation, NZ, 2021)

A heart attack needs urgent medical attention. If you think you are having a heart attack:

Call 111 and ask for an ambulance and let them know you may be having a heart attack.
If available, chew one aspirin, unless you have been previously advised not to take aspirin.
Rest quietly and wait for the ambulance.
Get someone to wait with you, if possible.
Remaining calm means you are less likely to suffer some of the heartbeat disturbances that create problems for you and your immediate medical advisors.

Minutes matter with a heart attack and early treatment can be life-saving. Make sure you have a heart attack action plan so you know what to do if you have a heart attack - read about heart attack action plans below.

What happens in the ambulance?

Ambulances attending people with chest pain generally have a paramedic crew member trained in coronary resuscitation. They also have all the appropriate equipment and medicines, including a defibrillator, which can deliver a measured electric shock to your heart if a dangerous heart rhythm occurs.

They will also have an ECG (electrocardiogram) monitor. They will set up an intravenous line (a soft tube placed inside a vein) so the paramedic can give you drugs quickly and effectively. You may be given aspirin and pain relief by the ambulance officer.

What happens in hospital?

Once at the hospital, you will be treated in the emergency department. The doctors will perform tests to find out whether or not you have had a heart attack. These tests include an ECG and blood tests for cardiac enzymes (these are released into your body by damaged heart muscle cells). Read more about heart disease tests.

You will be given medicine to help you recover. This may include a thrombolytic (clot busting) drug, which helps to break down the clot. You may need a procedure called an angioplasty to widen a coronary artery.

Once your condition is stable, you will be transferred to a specialist ward called the Coronary Care Unit (CCU). As your heart becomes more stable, the ECG monitoring will be taken away. You will be able to walk gently around the ward, with help.

You may be given medicine, including aspirin, which helps to reduce your risk of more clots developing. Further blood tests will be needed before you can go home. If there are no more problems you can look forward to going home in a few days.

What happens when I am discharged from hospital?

Cardiac rehabilitation is an important part of recovery. It can significantly increase your chances of recovering successfully and help in preventing another heart attack.

For more information about the recovery process, see the Heart Foundation's booklet Living well after a heart attack.(external link)

During a heart attack, part of your heart is starved of oxygen. Heart muscle is especially sensitive to a drop in oxygen carried in your bloodstream. This drop can interrupt your heart's rhythm and can cause it to suddenly stop beating. This is known as cardiac arrest. Cardiac arrest is life-threatening and requires immediate medical attention. Read more about cardiac arrest.

(Heart Foundation, NZ)

Coronary arteries are blood vessels that supply the heart muscle with blood and oxygen. In a heart attack there is a sudden blockage of a coronary artery by a blood clot.

If the flow of blood isn’t returned quickly, that section of heart muscle becomes damaged from lack of oxygen and starts to die. This results in poor beating action of that area, so the blood from your heart can’t get to vital organs like your brain. Your heartbeat may become irregular, further reducing the blood needed elsewhere.

If blood flow is not returned to the heart muscle within 20–40 minutes, irreversible death of the heart muscle will begin. Muscle continues to die for 6–8 hours, at which time the heart attack is usually ‘complete’. The dead heart muscle is eventually replaced by scar tissue.

What leads to this happening?

A heart attack can happen out of the blue, but it is more commonly the result of 3 processes:

the development over many years of fatty deposits (plaques) on the walls of your arteries
a clot forming on one of the plaques, resulting in a blockage of that artery
the blockage stopping blood flow to a section of heart muscle and, sometimes, the electrical impulses your heart responds to also stop working properly.

Fatty plaques can start building up on the inside walls of your coronary arteries (atherosclerosis) at an early age. Over the years, the build up of these plaques increases and they become larger. As a result, your arteries gradually become narrower and less elastic. At this stage you may experience chest pain (also known as angina).

As your arteries narrow, there is less room for blood to flow through. If a clot forms on the plaque, the artery can become blocked, cutting off the blood supply to part of the heart muscle. This is when a heart attack occurs.

A number of factors increase your chances of developing coronary heart disease. The more risk factors you have, the greater your chance of having a heart attack. You can’t change some of your risk factors – such as your age, sex, ethnicity and family history – but there are many others you can, such as smoking, blood pressure, weight, activity level and how much alcohol you drink.

Making positive changes to reduce the impact of these risk factors have will dramatically reduce your risk of cardiovascular disease and heart attack.

Read more about heart disease risk factors.

Minutes matter with a heart attack and early treatment can be life-saving. Make sure you have a heart attack action plan.

Know the warning signs

Heavy pressure, tightness, crushing pain or unusual discomfort in the centre of your chest lasting more than 10–15 minutes. This may stop or get less intense and then return. This symptom may not be the most noticeable symptom, especially in women.
Pain spreading to your shoulders, neck, jaw and/or arms, and in some cases, through to your back.
You may also sweat, have a sick feeling in your stomach, feel dizzy and be short of breath. These symptoms are the ones women most commonly notice.

Take action immediately

Dial 111, ask for the ambulance service and tell them you are having a possible heart attack.
If available, chew one aspirin, unless you have been previously advised not to take aspirin.
Rest quietly and wait for the ambulance.

Get it checked out

People often are not sure what's wrong and wait too long before getting help. The warning signs of a heart attack vary and it is possible to have no pain (especially in women and people who have diabetes) or the only sign may be indigestion-type pain.

Even if you're not sure it's a heart attack, have it checked out. Fast action can save lives. Calling 111 is almost always the fastest way to get life-saving treatment. Emergency medical services staff can begin treatment when they arrive. Do not travel by car if there is a possibility of a heart attack occurring.

Heart attack(external link) Heart Foundation, NZ
Heart attack(external link) NHS, UK
Heart attack – explained(external link) American Heart Association, US