coronary arteries are the source of the blood supply to the heart muscle which gives the required energy to pump . in general the arteries all over body has the fucntion to supply oxygen
as their form of energy to work normally whether it is heart muscle or any other muscle or organ. the clot blocks the supply of blood to the the heart muscle which undergoes necrosis
or damage to heart muscle therby it does not pump normally' and you develop chest pain
and results in hear attack'