A heart attack is a life-threatening medical emergency caused by the blood supply to the heart being blocked.
Heart attacks can cause permanent damage to muscles in the heart. A heart attack is also known medically as a myocardial infarction (MI).
Heart attack symptoms
Always call 999 for an ambulance if you think someone is having a heart attack.
Symptoms can vary from person-to-person, but can include:
Emergency care for a heart attack
While waiting for the ambulance, make sure the person is comfortable. They can be given a 300mg aspirin tablet to chew slowly to help thin their blood - as long as they are not allergic to aspirin.
Use of an automated external defibrillator ( AED) or giving cardiopulmonary resuscitation (CPR) are not needed for heart attacks - but this can save lives when used for a complication of heart attacks, called a cardiac arrest.
If this has happened, the person may not be breathing, moving or responding when spoken to or touched.
What causes heart attacks?
The main cause of heart attacks is heart disease, also called coronary heart disease (CHD).
Cholesterol causes deposits to build up over time in blood vessels to the heart. These deposits are called plaques. If one of these bursts or ruptures, an artery can get blocked causing a heart attack.
Other causes include:
Types of heart attack
STEMI (segment elevation myocardial infarction) - the most serious type where the blood flow has been stopped for some time causing significant heart muscle damage.
NSTEMI (non-ST segment elevation myocardial infarction) - a less severe - but still serious - type of heart attack after a partial blockage of an artery.
Unstable angina, with a very restricted flow of blood but no lasting heart muscle damage.