Heart Disease UK

A blockage in the heart's arteries may reduce or completely cut off the blood supply to a portion of the heart. This can cause a blood clot to form and totally stop blood flow in a coronary artery, resulting in a heart attack (also called an acute myocardial infarction).
Irreversible injury to the heart muscle usually occurs if medical help is not received promptly. Unfortunately, it is common for people to dismiss heart attack symptoms.
Many medical experts say the body likely will send one or more of these warning signals of a heart attack.
The actual diagnosis of a heart attack must be made by a doctor who has studied the results of several tests. The doctor may:
Review the patient's complete medical history.
Give a physical examination.
Use an electrocardiogram (or EKG) to discover any abnormalities caused by damage to the heart.
Use a blood test to detect abnormal levels of certain enzymes in the bloodstream.