Restenosis After Angioplasty and Stenting

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Restenosis is the name given to the gradual narrowing of a coronary artery following an angioplasty and stenting procedure.

Restenosis was recognized in the very earliest days of angioplasty as the greatest limitation of this procedure. After angioplasty alone, restenosis occurs in 40 - 50% of patients within 3 - 12 months. Indeed, the reason stents were developed was to reduce the incidence of restenosis.

Even with the first generation of bare metal stents (BMS), the incidence of restenosis was substantially reduced (to roughly 20 - 30% in 12 months). The use of drug-eluting stents (DES), in which the stents are medicated to inhibit the tissue growth that leads to restenosis, has further lowered the risk of restenosis. Most studies with DES report a restenosis rate of between 5 - 20% at one year.

Why Does Restenosis Occur?

Angioplasty (and stent placement, since it is always accompanied by angioplasty) is a form of tissue trauma. A balloon is passed across an atherosclerotic plaque in a coronary artery and then it is inflated – thus compressing the plaque, and widening the opening of the artery. Compression (or “smashing,” if you prefer) of the plaque is not a genteel process, and virtually always creates trauma to the blood vessel wall.

Restenosis occurs as a result of tissue growth at the site of treatment.

It can almost be thought of as a result of “healing” of the trauma that is induced by angioplasty. The endothelial cells that normally line the coronary artery proliferate at the site of the trauma. If this proliferation of endothelial cells becomes over exuberant, the cells can obstruct the blood vessel at the site of the stent.

Restenosis can also occur as a result of recurrent atherosclerosis – the process that caused the coronary artery blockage in the first place. Atherosclerosis as a cause of restenosis tends to appear long after the procedure - a year or more. The more typical restenosis - which is usually seen within 6 months and almost always within 12 months following the procedure, is usually caused by endothelial tissue growth.

Restenosis vs. Thrombosis

Restenosis should be differentiated from stent thrombosis - the sudden occlusion of a stent from the formation of a blood clot. Stent thrombosis is usually a catastrophe, since it often produces sudden and complete blockage of the coronary artery. If stent thrombosis occurs, it is usually seen early - within days or weeks of the procedure. The risk of thrombosis is greatly reduced with the use of platelet-inhibiting drugs.

There is also a small but real risk of late stent thrombosis - thrombosis occurring a year or more after the stent was placed - and in recent years it has become apparent that anti-platelet drugs should be continued for three years or more in many patients who receive coronary artery stents.

The only good treatment for thrombosis is to prevent it - once it occurs, heart damage or death is very likely to result.

Stent thrombosis is not reduced by using DES instead of BMS, and indeed there is some evidence that late thrombosis may be more of a problem with DES.

How Is Restenosis Treated?

The use of DES has greatly reduced the incidence of stent restenosis. However, DES have not eliminated the problem.

Once restenosis has occurred, treatment usually involves a repeat procedure - typically, a repeat angioplasty, often with the insertion of a second stent. A DES is almost always used in this situation.

Non-invasive therapy is also an alternative. Angina can often be controlled with drug therapy. Coronary artery bypass surgery is a good alternative for patients with stent restenosis (especially if the restenosis recurs after a second angioplasty and stent). Non-traditional therapy, such as EECP, is also an option.


Restenosis remains an issue with coronary artery stent therapy, though it is much less a problem today than in the time before DES.


Dangas GD, Claessen BE, Caixeta A, et al. In-stent restenosis in the drug-eluting stent era. J Am Coll Cardiol 2010; 56:1897.

bMishkel GJ, Moore AL, Markwell S, et al. Long-term outcomes after management of restenosis or thrbosis of drug-eluting stents. J Am Coll Cardiol 2007; 49:181.

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