Classic heart attack signs are chest pain, tightness, heaviness or squeezing in the centre or left of the chest that may spread to one or both arms, the jaw, neck, back or stomach. Other signs include sudden shortness of breath, breaking into a cold sweat, feeling sick or being sick, lightheadedness and a sense of impending doom.
Symptoms can be subtler in women, older adults and people with diabetes, sometimes showing as unusual fatigue, indigestion-like discomfort, or breathlessness without dramatic chest pain. Do not wait to see if it passes.
This is a medical emergency. Call your local emergency number (such as 911, 999 or 112) straight away, not your doctor. While waiting, sit and rest. Aspirin is sometimes advised by emergency dispatchers but only take it if instructed and if you are not allergic. Fast treatment saves heart muscle and lives.