If your coronary arteries become partially blocked, it can cause chest pain (angina).
This can be a mild, uncomfortable feeling similar to indigestion. However, a severe angina attack can cause a painful feeling of heaviness or tightness, usually in the centre of the chest, which may spread to the arms, neck, jaw, back or stomach.
Angina is often triggered by physical activity or stressful situations. Symptoms usually pass in less than 10 minutes, and can be relieved by resting or using a nitrate tablet or spray.
Read more about treating angina.
If your arteries become completely blocked, it can cause a heart attack (myocardial infarction).
Heart attacks can permanently damage the heart muscle and, if not treated straight away, can be fatal.
Dial 999 for immediate medical assistance if you think you're having a heart attack.
Although symptoms can vary, the discomfort or pain of a heart attack is usually similar to that of angina. However, it's often more severe and may happen when you're resting.
During a heart attack, you may also experience the following symptoms:
- pain in other parts of the body - it can feel as if the pain is travelling from your chest to your arms, jaw, neck, back and abdomen
The symptoms of a heart attack can also be similar to indigestion. For example, they may include a feeling of heaviness in your chest, a stomach ache or heartburn.
A heart attack can occur at any time, including while you're resting. If heart pains last longer than 15 minutes, it may be the start of a heart attack.
Unlike angina, the symptoms of a heart attack aren't usually relieved using a nitrate tablet or spray.
In some cases, a heart attack can occur without any symptoms. This is known as a silent myocardial infarction and is more common in elderly people and people with diabetes.
Heart failure can also occur in people with CHD when the heart becomes too weak to pump blood around the body. This can cause fluid to build up in the lungs, making it increasingly difficult to breathe.
Heart failure can occur suddenly (acute heart failure) or gradually over time (chronic heart failure).
What to do if someone has a heart attack
When someone has a heart attack, a bystander - often a relative with no medical expertise - is usually the first on the scene.
However, less than 1% of the population have attended an emergency life support course.