About Coronary Stents

  1. Home
  2. »
  3. Coronary heart diseases
  4. »
  5. About Coronary Stents

Coronary stents, also known as “coronary endoprostheses,” have been in use for about three decades.

This article aims to answer frequently asked questions from patients and their families.

A Bit of History

The first procedure aimed at improving blockages in the coronary arteries, called balloon angioplasty, was performed in the late 1970s.

This intervention uses a catheter, a long tube with an inflatable cylindrical balloon at its end, which is inserted through an artery in the groin or wrist and guided under X-ray into the heart vessel narrowed by a cholesterol plaque.

The balloon is then inflated to stretch and widen the blockage to improve blood flow.

It is then deflated, and the catheter is removed from the body.

Problems Associated with Balloon-Only Coronary Angioplasty

    • Tear in the Arterial Wall: The inflation of the balloon sometimes caused a severe tear in the arterial wall, requiring urgent cardiac surgery to restore blood flow.
    • Need to Repeat the Procedure: Another issue was the need to repeat the procedure after a few months in about 30% to 50% of cases. Since nothing could prevent the vessel wall from closing again, the artery would become narrowed once more, either due to “recoil” (the elastic memory of the artery) or due to the formation of scar tissue at the site of the dilation.

      While this procedure was revolutionary, it had its limitations.

Adding a Stent to the Procedure

To address these limitations, metal stents were developed.

Mounted and compressed onto the balloon catheter, they are advanced into the blood vessels after the artery has been prepared, or not, by conventional angioplasty.

When the balloon is inflated, it expands the stent until it is pressed against the vessel wall. The balloon catheter is then deflated and removed from the body, leaving the stent at the blockage site, creating a permanent structure to keep the artery walls open.

Coronary stents have been widely used since the early 1990s.

Types and Composition of Stents

  • Metal Stent: Made from stainless steel or alloys of platinum, chromium, cobalt, nickel, and titanium.
  • Bioresorbable Stent: Made with a sugar polymer that dissolves in the body over time. Still under development, long-term results have not met initial expectations.

Delivery Mechanism

Metal stents are typically deployed using balloon catheters, while some stents made of nitinol (a nickel-titanium alloy) are self-expanding and kept compressed on the catheter by a tiny retractable sheath. When the sheath is removed, the stent expands against the vessel wall.

This type of stent is most commonly used in peripheral angioplasty, such as for the dilation of leg arteries.

The First Stents

The first stents approved for clinical use were made of stainless steel.

They are known as bare-metal stents.

Problem of Restenosis

Although stents were very useful for repairing acute tears after balloon angioplasty, they were not very effective at preventing the risk of the repaired artery narrowing again after a few months.

The human body reacted to the presence of these foreign objects, and the excessive repair inside the stents created a new blockage called restenosis.

In about 25% of cases, and sometimes even more, the blockage was severe enough to require another intervention within 6 months following the initial procedure.

Development of Drug-Eluting Stents

The problem of restenosis inside a stent led to the development of new technologies to combat natural repair and scar tissue formation. These are drug-eluting stents.

These stents are coated with a compound containing an active drug against restenosis.

The drug is released over a period of several weeks to control the healing process.

Drug-eluting stents have reduced the risk of restenosis to less than 10%.

Chest Pain During the Stent Placement Procedure

During a vascular stent placement procedure, chest discomfort is not uncommon.

When the stent is deployed using the balloon catheter, blood flow in the treated vessel is temporarily interrupted for a few seconds. During the stent inflation, the patient may experience discomfort as the artery walls are stretched and nerve endings are stimulated.

Additionally, some small secondary arterial branches present in the main artery may be pinched by the stent mesh when it is inserted. This is generally a benign consequence of stent placement.

Possible Complications

Complications following the placement of a stent are relatively rare. Two types of complications can occur after the placement of a vascular stent:

  • Stent Thrombosis: The complete blockage of the stent due to the formation of acute blood clots.
  • Stent Restenosis: The gradual formation of scar tissue inside the stent, which can obstruct the vessel.

-Stent Thrombosis

A Foreign Body

After the stent is placed, the healing process begins, and the patient’s cells gradually cover the stent’s mesh. Before this process is complete, there is a certain risk of clot formation, as the stent is a foreign body, and the metal surface can activate blood coagulation.

A blood clot could form suddenly and cause a partial or complete blockage of the artery, leading to a heart attack.

This complication can be fatal, with most cases occurring within the first 30 days following the procedure.

In general, the expected rate of early stent thrombosis is about 1%, and beyond 30 days, it is between 0.2% and 0.6% per year.


To prevent clot formation in the stent, patients must take medications to maintain good blood flow within it.

Two Antiplatelet Medications to Take

Patients typically need to take two types of medications to inhibit the effect of blood platelets.

The first medication is aspirin, which generally must be taken indefinitely.

The other is either clopidogrel (Plavix), prasugrel (Effient), or ticagrelor (Brilinta). These medications are usually prescribed for at least one month, sometimes up to a year.

The most common cause of stent thrombosis is the discontinuation of one or both antiplatelet medications by the patient.

-Coronary Restenosis

Before the advent of drug-eluting stents, more than 25% of patients experienced restenosis caused by the natural repair process and the covering of cells over the stent.

This rate has been significantly reduced to less than 10% thanks to drug-eluting stents.


Stent Repair Compared to Bypass Surgery

In many cases, stent placement is a preferable, simpler, safer, and less invasive treatment compared to open-heart surgery.

Research is still being conducted to assess the reliability of multiple stent repairs compared to bypass surgery.

Stents Are Permanent

Once deployed, stents remain inside the vessel. They do not need to be removed. In fact, they cannot be removed.

There is no rejection by the body.

Stents Do Not Move or Migrate

Stents are stretched and expanded against the vessel walls and eventually covered by the patient’s own cells.

They are chosen based on the size of the vessel, and once properly deployed, the stents are securely anchored and cannot be dislodged.

Patients can safely resume their physical activities.

Stents Do Not Collapse

Coronary stents are placed in the arteries on the surface of the heart, within the chest. They cannot be compressed and do not spontaneously collapse.

However, as mentioned earlier, they can become acutely blocked by a blood clot or gradually by the formation of scar tissue.

Stents and Medical Imaging

Stents do not interfere with nuclear medicine scans, such as scintigraphy. You can safely undergo X-rays or CT scans with coronary stents.

If you need magnetic resonance imaging (MRI), inform the MRI technician that you have a coronary stent. Patients with any commonly used coronary artery stent can safely undergo an MRI immediately after stent placement.

It was originally thought that a waiting period of 6 weeks or more after implantation was necessary, but this concept has been abandoned, as there are no coronary artery stents made from ferromagnetic materials. (These are materials, such as iron, that form permanent magnets or are attracted to magnets.)

Stents and Travel

You can travel safely after a successful stent procedure. However, patients should disclose this information to their travel insurance company.

Coronary stents do not trigger metal detectors at airports. You can pass through security checkpoints without any issues.

Stents and Diet

Your diet has little to no effect on the healing process of the stent itself.

However, your healthcare team may recommend dietary changes to reduce the risk of future cardiac events or the progression of coronary artery disease.

Recurrent Chest Pain After a Stent Procedure

Stents are not perfect.

A new blockage in the area treated with the stent or a blockage elsewhere in your coronary arteries can cause new chest pain. Scar tissue may form in the area of your stent, leading to the narrowing of your artery over several months.

If this occurs, another stent can often be inserted and deployed inside the first to resolve the issue.

In some cases, coronary bypass surgery may be necessary.

There is no sure way to prevent the recurrence of chest pain, but exercise, quitting smoking, and a healthy diet can reduce this risk.

Stents Do Not Cure Coronary Artery Disease

Unfortunately, nothing cures coronary artery disease.

The stent does not replace medications or lifestyle changes (such as exercising more, quitting smoking, or eating a healthier diet). It has been shown that medications and lifestyle changes are beneficial for patients.

For individuals with stable coronary artery disease, the stent is an option in the cardiologist’s toolkit.

Stents Can Save Lives

The number of deaths related to heart attacks has remarkably decreased over the past 30 years.

Before the era of angioplasty, a quarter of patients suffering from a heart attack would die. Angioplasty and modern stents have reduced this rate to 5%.

Rapid Angioplasty in Myocardial Infarction

The placement of one or more stents has undoubtedly become the treatment of choice for patients suffering from a heart attack.

Heart attacks are caused by a blocked artery that prevents blood from flowing to the heart. Angioplasty and coronary stents can quickly restore blood flow in the obstructed artery.

We often say that “time is muscle.” The longer it takes to treat a patient suffering from a heart attack, the more the heart muscle can be damaged; the patient may even die. Therefore, it is crucial to respond quickly.

Stents Can Improve Quality of Life

The placement of a stent can be suitable for patients suffering from severe angina (chest pain caused by one or more narrowings in an artery), as well as for patients who do not respond to medications or who develop side effects from them.

In this context, the stent does not save lives, but it can help improve the quality of life.