Coronary artery disease and intermittent claudication are not causally related, but may manifest from the same cause. Intermittent claudication can be caused by narrowing of the blood vessels in the lower limbs due to atherosclerosis of the lower limbs, while coronary heart disease is essentially a disease in which the blood vessels in the heart become atherosclerotic, leading to narrowing of the blood vessels and insufficient blood supply to the heart. The two diseases therefore have the same basis of pathogenesis and may occur simultaneously.