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Conditions and treatments 

Coronary angiogram

What is a coronary angiogram?

A coronary angiogram is a test used to look at the main arteries that supply the heart with blood and oxygen, known as the coronary arteries. This test shows your doctor the exact location and seriousness of any narrowed areas in your coronary arteries.

The test can also give information about the blood pressure inside your heart and how well your heart is pumping. Your consultant can use this information to help decide on your treatment.


A coronary angiogram is also called an angiogram or cardiac catheterisation.

How do I prepare for the procedure?


  • Warfarin - you may need to stop taking Warfarin before the test. Your anticoagulant clinic doctor or hospital consultant will discuss this with you. Please ask either of them if you have any questions about this. If you have an artificial heart valve or a history of stroke, Warfarin should only be stopped on the night before you have the test.

  • Metformin - please stop taking Metformin 48 hours before you have the test. You should start taking it again 48 Hours after the test. Please ask your consultant if you have any questions.

  • You should take all of your usual morning medication (except Warfarin). However, as the test may take up to an hour, you may prefer to leave out any water tablets until after the test.

  • Please bring all your medication (including Warfarin and Metformin) with you to hospital.


Female patients

If you think you may be pregnant, please let us know beforehand. If you have not had a period in the 10 days before the procedure, we will need to carry out a pregnancy test. This is because the test uses X-rays that may be harmful to an unborn baby.

Eating and drinking

Please follow the instructions in your confirmation letter about eating and drinking before the test. You may drink water until it is time for your test.


Preparing to come to hospital

Please do not shave or remove hair from your chest, arms, legs or groin before coming into hospital. If needed, this will be done in hospital just before your coronary angiogram.

It is very important that you have a thorough shower or bath the night before you come into hospital. Please pay special attention to washing under any skin folds such as under the breasts, the groin and genital area.

Please contact the ward before you leave home to make sure a bed is available. You should also make arrangements for someone to take you home after the test, as you will not be able to drive for the first 24 hours.

Remember to bring with you:

  • all the medication you are currently taking
  • a dressing gown
  • slippers that fit well and have a good grip.


What happens during the test? 

The cath lab

The test usually takes 30 minutes to an hour to complete and is carried out in a cardiac catheterisation laboratory (cath lab). We will inject a local anaesthetic into your groin or wrist and you should not feel any pain.

If you feel anxious about this, you can have a sedative to help you relax.

During the procedure

A small cut is then made in the groin or wrist and the catheter is inserted into the blood vessel and directed to the heart using moving X-ray images as a guide.

Once the catheter reaches the heart, a special dye is injected through the catheter. The dye shows up any narrowed areas or blockages in your arteries on the X-ray. The dye injection may cause you to feel a hot flushing sensation for a few seconds. You may feel an occasional missed or extra heart beat, but it should not cause you to feel any pain.

We will take a few X-ray images and your cardiologist may ask you to take a few deep breaths and then to hold your breath. If you sometimes get angina, you may experience chest pain during the test, but it should not be worse than normal.

During the test, we will use a heart monitor to check your heart rate and rhythm. Please let either the doctor or nurse know if you have new pain or other symptoms, such as shortness of breath.

When we have finished taking the X-ray images, we will carefully remove the catheter and apply firm pressure to stop any bleeding in your groin or wrist. 

Sometimes a small plug, called an angioseal, is used to stop any bleeding and speed up your recovery.

Going home

Most patients are able to go home on the day of the test. If not, you should be able to go home the following morning. Before you go home, we will ask you to walk up and down the ward several times to make sure that the small wound in your groin has healed enough for you to go home. Your nurse will check this.

The dressing (bandage) will usually be removed before you go home. You may have some bruising and a little tenderness in this area. Remember to keep the wound clean and dry.

Please arrange for someone to drive you home. You should not drive for 24 hours after the procedure. If you have had a heart attack, you should not drive for at least a month after the procedure.

If you have any questions once you are at home, please contact the ward that you were admitted to. You will be given contact details before you are discharged.

However, if you feel you need treatment urgently, please contact your GP or go to the nearest accident and emergency (A&E) department.

Benefits and risks

What are the benefits of this procedure?

A coronary angiogram gives a better understanding of your heart and how well it is working. It means your consultant can plan the best treatment for your condition.

Are there any alternatives to this procedure?

This is currently the best way of finding out exactly where the narrowed areas in the coronary arteries are. It is an essential test if you are going to have surgical or catheter treatment for your coronary artery disease. Other tests such as a thallium scan or an exercise test can indicate if you have coronary artery disease, but cannot show where and how severe the narrowed areas are.

What are the risks of the procedure?

An angiogram is a relatively safe test and serious complications are rare. The overall risk of serious complications is less than one in a thousand.

All medical procedures carry some risk. It is important to remember that we would not recommend any procedure if we did not believe the benefits outweigh any risks.

The risks will depend on your overall health and the condition of your heart. Your doctor will discuss with you the risks specific to your condition in more detail.

What happens after the test?

Your cardiologist will look at the angiogram and may suggest one of the following:

  • continuing on your current medication

  • having treatment to widen your coronary artery using coronary angioplasty and/or a stent

  • having surgery to re-direct blood around the blocked arteries, by using another vein or artery, known as a coronary artery bypass graft. 

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London SW3 6NP
Tel: +44 (0)20 7352 8121