What is a heart attack?

Your heart disease
Your heart disease

If you’ve just had a heart attack or been diagnosed with unstable angina, it’s not unusual for you to be feeling shocked and scared. The treatment you may have had in hospital may have helped you to get well enough to be discharged and back at home – perhaps after just a few days. 

A shorter hospital stay after a heart attack doesn’t necessarily mean your condition is any less serious, but the good news is that there’s an awful lot you can do to help yourself get better. And lots of help is available from healthcare professionals and support groups to get you on the road to recovery.

What happens with a heart attack? 1

Your heart relies on your coronary arteries to carry oxygen-rich blood to it. But as you get older, your arteries start to harden and get narrower, restricting that supply of blood. This is a process known as ‘atherosclerosis’. 

This process can be speeded up by fatty deposits of cholesterol, known as ‘plaques’. They can stick to artery walls and narrow them even more. If one of these plaques ruptures, it can cause your blood to clot and block the artery, cutting off blood supply. As the heart is suddenly not getting as much blood sent to it, it’s starved of oxygen and this causes a heart attack – known in medical-speak as a ‘myocardial infarction (MI)’. 

There are two types of heart attack: 2

  1. If your arteries are completely blocked it’s called an ST-elevation myocardio infarction, or "STEMI". This is an emergency and is treated by urgently having a proceedure to open the blocked artery. Opening the blockage as quickly as possible can limit the extent of damage and scaring of the heart.
  2. If a severely reduced amount of blood can still flow through the arteries, it’s called a non-ST-elevation myocardio infarction, or "NSTEMI", which still requires urgent treatment in hospital. This may be investigated and managed over a few days rather than unblocking the arteries as an emergency, although this can sometimes be required.

In unstable angina, the blood flow to your heart is reduced, but less severely. It’s a sign your heart function is being compromised and you’re more at risk of a future heart attack or a stroke. The symptoms of unstable angina can feel the same as a heart attack, and doctors won’t know which you’ve had until after an ECG (where electrodes are attached to your skin to measure your heart’s activity) and troponin blood test, often along with other investigations such as an angiogram.

What causes heart attacks? 3

Coronary heart disease is when your arteries harden and narrow. High cholesterol is one reason for this, and it’s also linked to a high-fat diet. Most heart attacks happen when one or more of our coronary arteries become narrowed with fatty deposts and may become even more narrow or blocked by a blood clot.

Other risk factors include:

Smoking: Cigarette smoke directly damages the artery linings. Cholesterol particles are covered by a non-stick coating which smoke can reduce, making it more likely to stick to coronary arteries. 

Being overweight: Carrying excess weight means your heart has to work harder, and you’re more at risk of a heart attack. 

Drinking too much: Moderate alcohol can have some protective effects towards the heart, but if you drink excessively you lose that benefit and are putting your heart at increased risk. 


There is a lot you can do now that you’re home after a heart attack. Read up about your medications here