Coronary Angioplasty /
Percutaneous Coronary Intervention (PCI)
/ Coronary Stent
These are interchangeable terms for the procedure where a narrowed coronary artery is opened, typically with a balloon and a stent. A coronary stent is an expandable mesh tube made of medical-grade stainless steel or cobalt alloy metal, which is expanded within the artery to relieve a narrowing, and keep it open. It remains in the artery permanently.
The procedure can be carried out straight after undertaking an angiogram. This is more likely after an acute presentation (threatened or evolving heart attack). Electively, this would be performed for one or more of the following:
- The patient had symptoms related to that narrowing despite being on good anti-anginal therapy
- There is a recent history of unstable symptoms (pain coming at reduced exercise or pain at rest)
- It is felt that the narrowing is in a place where a significant amount of heart muscle is at risk (as assessed either with a prior functional test, or a test performed at the time of the angiogram)
At the time of the angiogram, further tests may be carried out to assess the severity of a narrowing:
- A pressure wire study involves passing a fine wire down the affected artery and measuring the pressure difference across the narrowing. If this difference is above a pre-determined threshold, the implication is that stenting the artery would benefit the patient.
- An intravascular ultrasound (IVUS) gives information from within the artery. As well as assessing the severity of a lesion, it also provides information about the characteristics of a narrowing, which may help to decide the best treatment.
If a narrowing is identified, and none of the above criteria apply, the results of the angiogram should be discussed with the patient and all management options discussed. These discussions should include the risks of undertaking the procedure against the risk of not doing it. The typical risk quoted for an elective is PCI is 1% for serious complications, which includes causing a heart attack, stroke or death. This risk can vary depending on the complexity of the procedure.
The procedure of angioplasty (see diagram) involves passing a fine wire (guide wire) through the tube inserted through the wrist or groin beyond the narrowing. A balloon (typically 2.5mm in diameter) is then fed over this wire, positioned at the narrowing, and then inflated. This is then removed and a stent (on a balloon) positioned in a similar fashion. This is inflated and should scaffold the artery open. Sometimes further balloon inflations are required to expand the stent to fit the artery.
After the procedure, patients are required to take 2 anti-platelet drugs to reduce the risk of a clot forming in the stent whilst it is being incorporated as part of the artery. The usual time is 1 year but this can be reduced depending on the type of stent and if there is concern over the increased risk of bleeding on 2 drugs. Most patients continue on a single anti-platelet indefinitely.
There are ongoing risks after the stent is implanted – the commonest is a blood clot forming in the stent and blocking the artery. The risk of this reduces the longer the time from the procedure. A longer term complication is in-stent restenosis, where the “skin” that grows over the stent after implantation, keeps growing and re-narrows the artery. If this occurs, this can be treated with further angioplasty or bypass surgery.