Coronary heart disease (CHD) is usually caused by a build-up of fatty deposits on the walls of the arteries around the heart (coronary arteries).

The fatty deposits, called atheroma, are made up of cholesterol and other waste substances.

The build-up of atheroma on the walls of the coronary arteries makes the arteries narrower and restricts the flow of blood to the heart. This process is called atherosclerosis. Your risk of developing atherosclerosis is significantly increased if you smoke.