During a heart attack, a blood clot completely obstructs the artery and deprives the heart of oxygen supply, causing heart muscle cells to die and leading to permanent damage, explains WebMD. Blood clots form when a plaque ruptures and platelets surround the area.
The coronary arteries are responsible for providing oxygen-rich blood to the heart, says WebMD. Blood doesn’t flow properly in people with coronary artery disease because their coronary arteries become narrow. Plaque deposits result from the accumulation of fatty substances, proteins, calcium and inflammatory cells within those arteries.
Another possible cause of a heart attack is a coronary spasm, in which the arteries spasm repeatedly, leading to a lower blood supply to the heart, states WebMD. People at rest and those who don’t have a severe coronary artery disease can suffer a coronary spasm.
The extent of damage during a heart attack depends on the size of the heart region being supplied by the obstructed artery, notes WebMD. The speed of treatment also significantly affects the amount of damage to the heart. It takes around eight weeks for the heart muscle to heal following an attack. A scar forms once the wounded area heals, but the new scar tissue cannot contract. This means the heart loses some of its pumping ability depending on the size and site of the scar.