Heart attacks are a serious medical emergency where the supply of blood to the heart is suddenly blocked.
A lack of blood to the heart can seriously damage it and can be life-threatening.
Symptoms of a heart attack can vary and can sometimes be considered a little less serious, so it's important to know what to look out for.
What are the symptoms?
Signs that you or someone else has a heart attack include pain in the chest or in other parts of the body, feeling dizzy or dizzy, and sweating.
Shortness of breath, feeling sick or being sick, coughing or wheezing and feeling an overwhelming sense of anxiety that looks like a panic attack are other symptoms.
Chest pain usually causes a feeling of pressure, tightness or squeezing in the middle of the chest.
Although chest pain may seem like an obvious indication, you will have a heart attack and the pain can often be very severe, some people experience only mild pain, similar to indigestion.
In some cases, people can not feel chest pain at all, which is especially the case for women, the elderly and people with diabetes.
"It is possible to have a heart attack without experiencing classical chest pain," said the British Heart Foundation.
"This is more common in the elderly, women or people with diabetes, because the condition can cause nerve damage that can affect how you feel your pain."
Pain in other parts as the body can feel as if it travels from the chest to the arms, jaw, neck, back and abdomen.
"It is the general pattern of symptoms that helps to determine if you are having a heart attack," the NHS said.
"If you suspect the symptoms of a heart attack, call 999 immediately and ask for an ambulance."
"Do not worry if you're in doubt – Paramedics would rather be called to discover that a genuine mistake was made than to be too late to save someone's life."
If you suspect that you or someone else has a heart attack, it is important to rest while waiting for the ambulance.
Aspirin can be given to the person concerned if he or she is not allergic to it, because it helps to dilute the blood and restore the blood supply to the heart.
If you think you have a heart attack, only take aspirin if it is readily available. Do not stand up and look for it because this can unnecessarily burden the heart, warns the British Heart Foundation.
In some cases, a heart attack can lead to cardiac arrest, which means that the heart stops beating.
Signs that someone may have had a heart attack include if they do not seem to breathe, they do not move or respond to any stimulus such as being touched or spoken.