Coronary heart disease is caused by the building up of plaques in the arteries of the heart. these arteries are the blood vessels that supply blood to the heart. yes po. heart also needs blood supply. so what happens when there is plaque? The arteries will harden, decrease on diameter, and will be deprived of oxygen. Hence, the arteries with plaque will die. if it dies it will no longer be able to supply oxygenated blood to the heart.