Blood tests for heart disease

Testing your blood for heart disease

A blood test takes a small sample of your blood which is then sent for testing in a laboratory.

Your doctor or nurse may do it, or you can have your blood test at a hospital, local health clinic or pathology service. Blood tests can measure the levels of substances in your blood to show if your heart has been damaged or if you are at risk of cardiovascular disease

Why is the blood test done?

Blood tests can provide your GP with an indication of your overall health or be used to detect specific health issues. In terms of your heart, a blood test can confirm if you’ve had a heart attack and measure the extent of the damage. It can also help your doctor work out your future risk of heart disease.

How is the blood test done?

When you have a blood test:

• Your arm is first cleaned with an antiseptic.
• A tourniquet (an elastic rope) or a blood pressure cuff is placed around the top part of your arm. This causes the veins in your lower arm to fill with blood. The person taking your blood may ask you to clench your fist or move your hand to help this.
• A needle is inserted into the vein, usually in the inside of your elbow. Blood is then collected in a vial or syringe. Depending on the type of tests your GP has requested, more or less blood might be collected.
• Once your blood is taken, the needle is removed, gentle pressure is put on the area to stop any bleeding, and then a small covering is applied. The whole procedure usually only takes a few minutes.

What does the blood test show?

There are a few different things in your blood that can help diagnose any heart issues or predict your risk of heart disease.

• Troponin – this is the most common test used to diagnose if you have had a heart attack. Troponin is a substance that is released by your heart tissue when it has been damaged, such as during a heart attack.
• Cholesterol – cholesterol is a waxy, fat-like substance that your body uses for several normal processes. However, too much cholesterol can develop fatty deposits in your blood vessels. This makes it difficult for blood to flow through the arteries. A blood test for cholesterol usually tests for low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL cholesterol and triglycerides.
• International normalised ratio (INR) – this test measures how long it takes your blood to form a clot. If your blood clots too readily it can put you at risk of having a heart attack or stroke. The test is used to decide if you need, and what dose you may need, of a medicine to prevent clots, such as warfarin.

Your GP may also request blood tests for kidney disease or diabetes – as these can influence your risk of developing cardiovascular disease in the future. This may be done as part of a Heart Health Check.

Preparing for the blood test

There is usually no special preparation for a blood test. For some tests your GP might ask you to not eat or drink anything before the test, but you should check if this is necessary for your individual health situation.

You should make sure you’re not dehydrated before the test by keeping up your fluid intake, as this can make your veins easier to find for the test.