People with PAD are at high risk for a heart attack or stroke because of the build-up of plaque in their blood vessels. If a piece of plaque breaks off, red blood cells (platelets) clump together inside the blood vessel to form a clot on top of the plaque. This clot can limit or even block the flow of blood to your heart or brain, causing chest pain, a heart attack or stroke. Medications are available that can help prevent blood clots from forming, reducing the risk of heart attack or stroke.