What is a Coronary Angiography?
Coronary angiography is a diagnostic procedure to observe how blood flows through the heart’s arteries and blood vessel function using X-ray imaging technology. It lets doctors see exactly how blood flows through the arteries of your heart. It detects artery narrowing and blockage, and is the most commonly performed type of cardiac catheterisation procedure used to diagnose and treat conditions related to the heart and blood vessels.
The coronary arteries are the blood vessels that supply your heart muscle with oxygen-rich blood. Over time, fatty deposits (plaque) can build up inside them and make them narrower, which reduces blood flow to the heart. This is called coronary heart disease. A severe narrowing, or a blood clot forming on the plaque, can cause chest pain or a heart attack.
During a coronary angiography procedure, a contrast dye is injected into the heart’s blood vessels. The dye shows up clearly on X-ray images, which helps your doctor see where any blockages are, and how severe they are.
If a significant blockage is found, your doctor may perform a coronary angioplasty to insert a stent, a tiny mesh tube that keeps the artery open, or recommend coronary bypass surgery to treat the blockage. Your doctor will discuss these options with you before the procedure and, whenever possible, afterwards.
Why Might You Need a Coronary Angiography?
Your doctor may recommend a coronary angiography if you:
- Have chest pain, tightness or pressure (angina), or breathlessness, that may be caused by narrowed heart arteries
- Are having, or have just had, a heart attack, where a quick view of the arteries is needed to decide on treatment
- Have had abnormal results on other heart tests, such as a stress test, an ECG or a CT scan of the heart arteries
- Have heart failure or a weak heart muscle, and your doctor needs to find out whether blocked arteries are the cause
- Have had a previous stent or bypass operation, and have symptoms that have returned
- Need heart or other major surgery, and your doctor wants to check the state of your heart arteries first
Why This Matters in Singapore
Heart disease is a leading health concern in Singapore. Ischaemic heart disease, which is caused by narrowing of the heart arteries, is the third leading cause of death here, accounting for about 1 in 5 deaths (19.6% in 2024), according to the Ministry of Health. Together with stroke, heart and blood vessel diseases account for almost 1 in 3 deaths.
Many of the main risk factors are common here. About 1 in 3 residents aged 18 to 74 has high blood pressure, about 1 in 11 has diabetes, and about 3 in 10 have high blood cholesterol, based on the National Population Health Survey for 2023 to 2024. These conditions can silently damage the arteries for years. Diets that are high in salt, fried food and saturated fat, smoking and inactivity add to the risk.
Heart attack symptoms are not always dramatic. Some people, especially older adults, women and people with diabetes, have milder symptoms such as breathlessness, unusual tiredness, nausea or discomfort in the jaw, neck or back. If you have chest pain or other symptoms that worry you, please see a doctor promptly. If it is severe, lasts more than a few minutes or comes with sweating or breathlessness, call 995 for an ambulance.
Preparing for your Coronary Angiography
- Tests before the procedure: You may be required to undergo an MRI or a CT scan before the procedure to identify problems with your heart. Blood pressure and blood sugar tests are done to ensure you are fit enough to proceed with the procedure. You may also have blood tests, to check your kidney function and blood count, and an ECG.
- Fasting: You should fast for at least 8 hours before the procedure. Your doctor or nurse will tell you if you may take sips of water with your medication.
- Your medication: Tell your doctor about all of your medicines, especially blood thinners such as warfarin, aspirin, clopidogrel and newer anticoagulants, and diabetes medications such as metformin and insulin. Some may need to be adjusted or stopped before the procedure.
Do not stop any medicine on your own, as stopping heart medicines suddenly can be dangerous.
- Allergies and kidney problems: Tell us if you have ever had a reaction to contrast dye, iodine, latex or any medicines, and if you have kidney problems, because the dye is cleared through the kidneys.
- Pregnancy: Tell us if you are pregnant or think you may be pregnant, as X-rays can affect an unborn baby.
- What to wear: You will be required to change into a hospital gown. Leave jewellery and valuables at home.
- Consent: Your doctor will explain the procedure, its benefits and its possible risks, and ask you to sign a consent form. This is the time to ask questions. If a blockage is found, ask your doctor in advance whether treatment, such as angioplasty, may be carried out during the same procedure.
- What to bring: Your doctor’s referral letter, your NRIC (or passport if you are an international patient), previous heart test reports, and a list of your medications.
- Plan your day: Arrange for someone to take you home and to stay with you for the first day. Some patients go home the same day, while others stay overnight, particularly if a stent has been placed. Your doctor will advise you.
What Happens During a Coronary Angiography?
- You will remain awake throughout the painless procedure. You will lie on a special X-ray table, and sticky patches will be attached to your chest to monitor your heart rhythm. Your blood pressure and oxygen levels will be monitored throughout.
- A thin IV line is placed in your arm, and you may be given a mild sedative to help you relax.
- Your doctor will clean the insertion area with an antiseptic wipe, and you will be given a local anaesthesia to numb the area. You may feel a brief sting and then pressure, but no pain.
- A thin tube called a catheter will be inserted into a blood vessel in certain parts of the body, such as the arm (wrist) or groin. Your doctor will choose the most suitable site for you.
- The catheter is moved slowly to the coronary arteries to examine them. You will not feel the catheter moving inside your blood vessels.
- A contrast dye is injected into the bloodstream, where it will flow through and detect any blockage of arteries. You may feel slight discomfort after the dye is injected, such as a warm flush or a feeling of needing to pass urine. This passes quickly.
- X-ray images are taken from several angles, while your doctor observes how the dye travels through your bloodstream on a monitor. You may be asked to take a deep breath and hold it for a few seconds, or to cough.
- Tell the team immediately if you have chest pain, breathlessness, or any other discomfort.
- When the images have been taken, the catheter is removed and pressure is applied to the site to stop the bleeding.
What Happens After a Coronary Angiography?
- You will rest in a recovery room until you feel well enough to leave. Nurses will check your blood pressure, pulse and the insertion site regularly.
- If the catheter was placed in your groin, you will need to lie flat and keep your leg straight for a few hours. If it was placed in your wrist, a tight band or dressing is placed on it, and you should keep the wrist still.
- Drink plenty of fluids, unless you have been advised to limit fluids, to help flush the dye out of your body.
- You may have some bruising, tenderness or a small lump at the insertion site. This normally fades within a few days to weeks.
- Avoid heavy lifting and strenuous activity, and avoid driving, for the period that your doctor advises. This is typically a few days, and longer if the groin was used or a stent was placed.
- You will be given a follow-up appointment to review your test results.
Understanding Your Results
Your doctor can often tell you what the angiogram showed soon after the procedure. The detailed results will be reviewed with you at your follow-up appointment. In general:
- Normal or mildly narrowed arteries: Your arteries are open or have only minor narrowing. Your doctor may recommend medication and lifestyle changes, and will look for other causes of your symptoms.
- Significant narrowing or blockage: One or more arteries are narrowed enough to restrict blood flow. Your doctor will discuss whether the best treatment is medication, an angioplasty with a stent, or bypass surgery. This depends on how many arteries are affected, where the blockages are and your overall health.
- Other findings: The angiogram can also show problems with how the heart is pumping or with the heart valves, and your doctor may recommend other tests.
Looking After Your Heart
- Keep your blood pressure, cholesterol and blood sugar under control, with regular check-ups
- Do not smoke, and avoid second-hand smoke
- Be active: aim for at least 150 minutes of moderate physical activity every week, as advised by your doctor
- Choose a heart-healthy diet with plenty of vegetables, fruit and wholegrains. Cut down on salt, fried food, fatty meat, and rich santan (coconut milk) based dishes
- Keep to a healthy weight, manage stress and get enough sleep
- Take your medication exactly as prescribed, including any antiplatelet medication given after a stent, and do not stop it unless your doctor tells you to
Should you feel unwell, contact your doctor immediately or call our 24-Hour Medical Urgency Clinic.
