Percutaneous Coronary Intervention

Synonyms Percutaneous transluminal coronary angioplasty (PTCA) formally called angioplasty and stenting

Percutaneous coronary intervention (PCI) is a procedure performed after a diagnostic coronary angiogram has confirmed the presence of a significant narrowing in one or more coronary artery. During PCI a small balloon is introduced across the narrowed segment of coronary artery and an expandable metal stent (a mesh) is inserted inside the vessel holding the artery open, restoring normal blood flow.

PCI enables the treatment of angina that has not been adequately controlled by medication alone. PCI will improve symptoms but has no role to play in improving a person’s longevity unless it is performed in the emergency setting of a heart attack, when reopening a freshly blocked coronary artery has been shown to improve a patient’s chance of survival. Depending on the clinical situation, elective (planned) PCI is either performed as an immediate follow-on from the initial angiogram or as a separate procedure on another occasion.

How is Percutaneous Coronary Intervention (PCI) performed?

The preparation for PCI is the same as for coronary angiography. Patients are asked not to eat any food for 6 hours before the procedure although clear fluids can be drunk until the procedure. All medication should be taken as usual (including aspirin) although anticoagulant agents such as Warfarin will need to be stopped several days before the procedure following the explicit instructions given by the attending Cardiologist. Diabetic patients will also be given specific advice.

PCI is either performed immediately after the diagnostic angiographic images have been obtained in or as a separate procedure. Once the initial coronary images have been obtained, identifying the narrowed segments of coronary artery that require treatment patients will receive blood thinning medication such as heparin that is required to prevent the development of blood clots.

After insertion of the introducer sheath, cardiac catheters are guided towards the heart under direct vision using x-ray screening in order to obtain the initial diagnostic coronary angiographic images. Once in place a special dye, or X-ray contrast, is injected into the catheter and a series moving pictures are recorded. The contrast shows up the outline of the coronary arteries and demonstrates the presence of any narrowing or blockages that are suitable for treatment by PCI.

A fine wire is then passed through the catheter and carefully steered across the segment of narrowed or blocked artery. Once the wire is in place, another thin tube with a tiny deflated balloon mounted on its end is passed over the wire across the segment of artery being treated. The balloon is inflated to high pressure opening the narrowing. Whilst the balloon is inflated, the blood flow will be temporarily interrupted and this may cause anginal chest discomfort, however this resolves once the balloon is deflated.

After the initial balloon inflation (this may need to repeated on a number of occasions) a stent (a metal mesh) mounted on a balloon catheter is then implanted, and squashes the fatty deposits against the artery wall when its balloon is inflated in the artery being treated. After a few seconds the balloon is deflated leaving the stent in place inside the vessel wall forming an inner tube, holding the vessel open restoring the blood flow to normal.

Stent Insertion

The whole procedure usually takes 45-60 minutes to perform, but it may take longer depending on the number and complexity of the narrowed segments that require treatment.

Below are coronary angiographic images before and after successful PCI in a patient with severe right coronary artery disease.

stent implantation 1

This image shows a large right coronary artery before treatment. There is a critical stenosis mid-vessel and further significant disease before the distal bifurcation (branch point)

initial stent implantation

Image demonstrating initial stent implantation across the more proximal of two significant stenoses

stent implantation 3

Final image following stent implantation demonstrating a large widely patent right coronary artery

What type of stent is used?

Many years ago when angioplasty was first carried out without stenting, the incidence or re-narrowing, (called restenosis) was high. Since stents have been routinely used the risk of restenosis has fallen dramatically. Stenting of a vessel is now the norm unless there are specific technical issues.

There are many different types of stent available for use in the UK. The two main types of stent that are licensed for use are bare metal (uncoated) stents and those that are drug-eluting stent, (coated with medication that reduces the risk of the artery becoming narrowed again (reducing the risk of restenosis).

The risk of coronary artery restenosis is affected by factors such as vessel anatomy, the length of the narrowing and the presence of other conditions such as diabetes or continued smoking. Overall the risk of restenosis is approximately 10%.

The National Institute for Clinical Excellence (NICE) recommends that a bare metal stent should be used to treat short, wide segments artery, and that drug-eluting stents should be used in cases where the arteries are smaller with longer segments of disease, since such arteries are more likely to become re-narrow. Approximately 80% of stents implanted in the UK are drug eluting.

Following PCI, it is possible for the coronary arteries to re-narrow or block (to develop restenosis). If this happens, it will usually occur within the first six months after the procedure. Restenosis restricts blood flow and will cause recurrent or worsening angina. Rarely restenosis may present as an emergency and may sometimes cause a heart attack.

If a coronary artery does become blocked again, further PCI may be recommended as determined by repeat angiographic images. On other occasions different treatment, such as coronary artery bypass surgery may be considered.

What happens after the procedure?

Once the PCI has been completed the catheter is removed from the artery in the same way as after a coronary angiogram although there is s slightly higher risk of bleeding as blood thinning agents such as heparin are required during PCI to prevent blood clot formation (see full description).

Like coronary angiography PCI is usually performed as a day-case procedure although on occasion patients are observed in hospital overnight.

There may be residual bruising and mild tenderness where the catheter was inserted. Patients usually feel back to normal within a few days. Patients are advised to avoid air travel for at least one week following PCI, but this advice will vary depending on the clinical scenario or in the presence of other medical conditions.

After the procedure patients should avoid strenuous activity, such as heavy lifting, until the small wound where the catheter was inserted has healed.

Driving after elective PCI

Group 1 licence – stop driving for one week Patients can recommence thereafter if there is no other disqualifying condition. The DVLA need not be notified.

Group 2 licence – stop driving for at least six weeks. Re-licensing may be permitted thereafter provided that other functional test requirements can be met and there is no other disqualifying condition. Details can be found on the DVLA website.

What medication needs to be taken?

Once a stent has been implanted all patients will require long-term medication to prevent the risk of sudden stent blockage (stent thrombosis). This will usually mean taking Aspirin life-long and an additional medication such as Clopidogrel or Ticagrelor for up to 12 months depending on the clinical situation and type of stent used.

Bare metal stents require at least 4 weeks of combination therapy; however drug eluting stents typically require treatment with both agents for 12 months.

Stopping either agent increases the risk of a stent thrombosis

The attending Cardiologist will always specify the duration of medication at the time of hospital discharge. Patients should not stop their medication without first consulting their Cardiologist.

Patients will be informed about any medication that they need to take, and will receive additional advice about improving diet and lifestyle.

What are the procedural risks of PCI?

A Cardiologist will not undertake PCI unless he or she feels the benefits, in improving symptomatic control of angina, outweigh the small procedural risk. PCI will only be performed on the advice of a Cardiologist based on the severity of a patient’s symptoms, often guided by results of other non-invasive cardiac assessments. Fortunately PCI is a safe procedure and serious complications are rare.

The potential procedural complications from PCI are the same as those after diagnostic coronary angiography although the procedural the risk of complications is higher. Most people do not experience serious problems following PCI, but as with all interventional procedures, there are some risks and possible complications.

The commonest and generally minor complication after PCI is bleeding from the puncture site where the catheter was inserted; occasionally it can leave a haematoma (a raised bruise) where blood collects under the skin. There is a small risk of injury to the artery where the sheath is inserted although this is rarely clinically important in cases performed from the wrist. The risk of bleeding is also lower for radial procedures than those performed from the groin (femoral).

Major bleeding is very rare even after procedures performed from a femoral approach.  Bleeding into the pelvis may require blood transfusion and can very rarely require an interventional radiologist or surgeon to repair any damage.

Major procedural complications

After PCI the overall risk of risk of any major adverse cardiac complication such as, heart attack, stroke, emergency surgery or death is low, approximately 1-2% in total. The risk is higher for people who already have serious heart disease and in those who present as emergency cases such as during a heart attack. The risk of planned elective PCI is much lower.

Other occasional complications include heart rhythm disturbance (arrhythmia), kidney injury and allergy to the contrast agent. Any patients with reduced kidney function are treated with extra caution and given intravenous fluid and medication to reduce the small risk of kidney injury. Patients with a known contrast allergy are given anti-histamines and steroids before the procedure.

Late complications after PCI

Stent thrombosis:

Even after a successful PCI there is a small risk that the stent will block; stent thrombosis. This is a risk until the stent becomes covered by a layer of cells (endothelium) inside the artery wall. The risk is highest in the first month, but can occur months or years after the PCI. Fortunately the risk of thrombosis is low in 1-2% of patients. The risk of stent thrombosis increases if patients do no take their antiplatelet medication as prescribed (see above)

Restenosis of the stent:

Even after successful PCI there is small risk that the treated area will re-narrow through a process called stent restenosis. This is due to excessive ‘healing’ of the vessel wall, which encroaches on the vessel. Typically, it develops within 3-6 months after the procedure usually as a return of angina; it can rarely present as unstable angina or a heart attack. The risk with modern drug eluting stents is approximately 10%.