In-Stent Restenosis

Restenosis is a renewed narrowing in a part of an artery that was previously widened. In the heart, restenosis usually occurs inside a coronary stent placed during angioplasty, which is why it is called in-stent restenosis. Restenosis can also occur in other arteries that have been widened, such as the leg arteries, but this page covers restenosis in the coronary arteries. Restenosis is not a sudden blockage by a blood clot. That sudden event is called stent thrombosis and is covered on the Stent Thrombosis page.

Why an Artery Can Narrow Again

After a balloon and stent widen the artery, the vessel wall has small injuries and then begins to heal. In some people, this healing process is excessive: smooth muscle cells and connective tissue grow thick inside the stent, so the opening of the artery narrows again. This type of narrowing usually appears within 3 to 12 months after the procedure. Years later, new cholesterol plaque can also grow inside the stent. Other contributing factors are a stent that did not expand fully, a stent that is too small, or a fractured stent frame.

How Often It Happens

In the era of bare-metal stents without a drug coating, re-narrowing was found in about 20 to 30 out of 100 patients. Drug-eluting stents, which slowly release a medicine that inhibits tissue growth, reduced this to fewer than 10 out of 100 patients. For this reason, ESC guidelines recommend drug-eluting stents for coronary stenting. The risk is higher in people with diabetes, small-diameter arteries, long narrowings, and narrowings at artery branch points.

How Restenosis Is Treated

Not every restenosis needs a procedure. If the narrowing is mild and does not reduce blood flow, your doctor may choose medicines and monitoring. If the artery needs to be reopened, the main options are a new drug-eluting stent inside the old stent or a drug-coated balloon. Imaging from inside the artery with IVUS or OCT helps your doctor see the cause of the narrowing before choosing an approach. For repeated restenosis or disease in many vessels, coronary bypass surgery may be considered. Artery-opening procedures are covered on the Coronary Angioplasty page and on the Percutaneous Coronary Intervention (PCI) page.

Your doctor will start by asking about your symptoms, when your stent was placed, and whether the pattern of chest pain is similar to your symptoms before the procedure. An ECG and stress tests, such as stress echocardiography or myocardial perfusion imaging, help assess whether any part of the heart muscle is not getting enough blood flow. Coronary CT can be used for large stents, but the metal frame often makes the inside of small stents hard to assess.

If your symptoms are typical or a stress test shows reduced blood flow, your doctor will perform coronary angiography. ESC guidelines recommend imaging from inside the artery with IVUS or OCT to look for mechanical causes of restenosis, such as a stent that did not expand fully or a fractured frame. FFR measurement can be used to decide whether the narrowing is severe enough to be reopened.

Go to the emergency room right away if chest pain occurs at rest, does not go away after 5 minutes, or comes with cold sweats and shortness of breath. Make an earlier follow-up appointment with a cardiologist if:

• Pain or heaviness in the chest during activity returns after stent placement
• You get short of breath or tired more quickly when walking or climbing stairs
• Symptoms appear in a pattern similar to your symptoms before the procedure
• You have diabetes and feel that your ability to be active has declined
• You are unsure whether the medicines you take after stent placement can be stopped