Heart stents need to be replaced if scar tissue forms over them due to an injury in the wall of the blood vessel, according to WebMD. This is called restenosis, and causes a dangerous narrowing of the arteries.
However, if the stent works as it should, it does not need to be replaced, explains the National Heart, Lung, and Blood Institute. When the stent is placed in a blood vessel, the patient's cells eventually grow over the metal mesh of the stent. In time, that area of the blood vessel resembles other, healthy blood vessels. Some stents are coated with medicine to keep scar tissue or blood clots from forming. These are called drug-eluting stents.
Doctors sometimes tell their patients to take aspirin or another anticoagulant for about a month after having a stent placed, states the National Heart, Lung, and Blood Institute. If the stent is drug-eluting, the patient may need to take anticoagulants for as long as a year. Some patients may need to take aspirin for the rest of their lives to prevent blood clotting. Stents are not a cure for atherosclerosis. To get the best results from a heart stent, the patient needs to eat a healthy diet, watch his weight, exercise and give up smoking.