If the Coronary CT Angiogram (or one of the other non-invasive tests outlined above) indicates that there is a significant narrowing in a coronary artery the patient would usually be advised to have an invasive coronary angiogram.
This gives much higher definition images of the arteries and allows them to be repaired with stenting at the same time.
The angiogram usually takes about five minutes. The patient lies on an X-ray table and is given sedation to make the procedure a comfortable and surprisingly stress free. Local anaesthetic is injected over the artery at the wrist and a 2mm soft plastic tube put into the radial artery at the wrist. A longer tube is then put into the short plastic tube and a soft guide wire fed up the artery to the heart over which a longer plastic tube is fed around to the heart. The long tube is then rested in the origin of each coronary artery and contrast media injected down the artery. A large X-ray camera then moves around the patient taking cine x-ray images from various angles.
There is a tiny serious complication rate of approximately four in a thousand. The angiogram will show clearly and precisely the nature of the narrowings in the arteries.
If a significant narrowing is found then a very soft guide wire can be passed down a tube resting in the origin of the coronary artery. Over this wire, a tube with a balloon on and a metal framework “stent” can be passed into the narrowing. This can then be inflated in the narrowing squashing the narrowing out of the way and in the process leaving the metal framework “stent” embedded in the artery-to stop it recoiling back to narrow the artery again. The most commonly used stents have a coating impregnated with a small amount of a cytotoxic agent to stop scar tissue forming at the site of the stent implantation and narrowing the artery again. Stenting will usually take about 30 minutes but can take longer.
Because the stent is a foreign body it is necessary to inhibit small particles in the blood (platelets) from sticking to it and causing a clot that blocks the artery. Therefore, the patient needs to take one platelet inhibitor life long (usually aspirin) and an additional one for 6 months to 1 year (usually Clopidogrel or Ticagrelor). It is very important not to stop the aspirin even for operations.
Stenting is a very successful method of relieving angina.
The alternatives to coronary stenting are medical therapy and coronary bypass grafting. Medical therapy can work well but sometimes the narrowing in the artery is so severe that stenting is the best option. Coronary bypass grafting is obviously a major operation (please see section on coronary artery bypass grafting).
The patient can go home the next day.