Like all other tissues and organs in the body, the heart needs a constant supply of oxygen-rich blood. If the blood supply to the heart is suddenly interrupted, heart muscles may be damaged and begin to die.

If this is not treated, heart muscles will experience irreversible damage. If a large portion of the heart is damaged in this way, the heart will stop beating (a cardiac arrest), resulting in death.

Coronary heart disease (CHD)

Coronary heart disease (CHD) is the leading cause of heart attacks. CHD is a condition in which the coronary arteries (the major blood vessels that supply the heart with blood) get clogged up with deposits of cholesterol. These deposits are called 'plaques'.

During a heart attack, one of the plaques ruptures (bursts), causing a blood clot to develop at the site of the rupture. The clot may then block the supply of blood running through the coronary arteries to the heart, triggering a heart attack.