1
Call 999.Tell them you think the person is having a heart attack.
2
Get them comfortable.Reassure them, and help them sit or lie in a comfortable position.
3
Aspirin.If the pain sounds like it's from the heart, help them take 300 mg of aspirin as soon as possible, ideally chewable or dissolvable. Don't give it to anyone allergic to aspirin, or anyone under 16.
4
Their own medication.If they have angina, help them take their own spray or tablets.
5
Stay with them.Keep checking how responsive they are until help arrives. If they become unresponsive and aren't breathing normally, start CPR.
The call handler will guide you. Tell them where you are and that you think the person is having a heart attack.