A myocardial perfusion (MPS) scan is a specialised heart test that shows how well blood flows to the heart muscle. It helps identify areas of the heart that may not be receiving enough blood, usually due to narrowing or blockages in the coronary arteries.

Myocardial perfusion scans can be suggested to patients with chest pain, breathlessness, or known coronary artery disease. Many people feel unsure when they hear the term for the first time, so this guide explains what an MPS scan is, why it is used, and what you can expect before, during, and after the test.

What Does a Myocardial Perfusion Scan Show?

The heart muscle needs a constant supply of oxygen rich blood to work properly. The coronary arteries deliver this blood. If these arteries narrow, parts of the heart may not receive enough blood, especially during physical activity or stress.

A myocardial perfusion scan shows how well blood reaches different areas of the heart muscle. It allows cardiologists to see whether blood flow is normal at rest and during stress. By comparing these images, doctors can identify areas where blood flow becomes reduced when the heart works harder.

This information helps determine whether symptoms relate to coronary artery disease and how severe any narrowing may be.

Why Is a Myocardial Perfusion Scan Performed?

Doctors use myocardial perfusion scans to investigate symptoms that suggest reduced blood flow to the heart. These symptoms often include chest pain, tightness, breathlessness, or unexplained fatigue during exertion.

The scan also helps assess known coronary artery disease. It shows whether existing narrowing affects blood supply and whether treatment is effective. In some cases, it helps guide decisions about medication, angioplasty, or surgery.

An MPS scan can also assess heart function after a heart attack or help clarify results from other tests when findings are uncertain.

How a Myocardial Perfusion Scan Works

An MPS scan uses a small amount of radioactive tracer. This tracer travels through the bloodstream and is taken up by healthy heart muscle cells. Areas that receive less blood absorb less tracer.

A special camera then detects the tracer and creates detailed images of the heart muscle. These images show how evenly blood flows through the heart.

The amount of radiation used is low and carefully controlled. For most people, the benefits of the test far outweigh the risks.

Stress and Rest Imaging

A myocardial perfusion scan usually involves two parts. One set of images is taken while the heart is under stress, and another is taken while the heart is at rest.

Stress may involve walking on a treadmill or receiving medication that makes the heart work harder. This approach allows doctors to see how the heart responds when demand for oxygen increases.

Rest images show how blood flows to the heart when it is relaxed. Comparing stress and rest images helps identify whether reduced blood flow is temporary or permanent.

What Happens During the Scan?

When you attend for a myocardial perfusion scan, a clinician will explain the process clearly. A small cannula is placed in your arm so the tracer can be injected.

For the stress part of the test, you may walk on a treadmill. If exercise is not suitable, medication is used to simulate the effects of exercise on the heart. Your heart rate, blood pressure, and ECG are monitored throughout.

After the tracer injection, you rest for a short period while it circulates through the heart. You then lie on a scanning table while images are taken. The camera does not touch you and the scan itself is painless.

The same process is repeated for the resting images. The full appointment can take several hours, although much of that time involves waiting between stages.

How to Prepare for a Myocardial Perfusion Scan

Preparation instructions vary slightly depending on the protocol used. You are usually asked to avoid caffeine for at least 24 hours before the test, as caffeine can interfere with stress medication.

You may also be advised not to eat for a few hours beforehand. Some heart medications may need to be paused temporarily, but you should only do this if your doctor gives clear instructions.

Comfortable clothing and shoes are recommended, especially if you will be exercising on a treadmill.

What Can the Results Show?

A myocardial perfusion scan can show normal blood flow, reduced blood flow during stress, or permanently reduced blood flow.

If blood flow appears normal at both rest and stress, significant coronary artery disease is unlikely. Reduced flow during stress that improves at rest often indicates reversible ischaemia, meaning part of the heart struggles to receive enough blood during exertion.

Areas with reduced blood flow at both rest and stress may indicate previous heart damage, such as scarring from a past heart attack. These findings help cardiologists decide on the most appropriate treatment or further testing.

How an MPS Scan Fits With Other Cardiac Tests

A myocardial perfusion scan does not replace other heart tests. Instead, it adds important functional information.

While tests such as ECGs and echocardiograms assess rhythm and structure, an MPS scan focuses on blood supply to the heart muscle. CT coronary angiograms show artery anatomy, whereas myocardial perfusion scans show how narrowing affects blood flow in real life. Together, these tests provide a complete picture of heart health.

Is a Myocardial Perfusion Scan Safe?

MPS scans have been used for many years and have a strong safety record. The radiation exposure is similar to that of other medical imaging tests and is kept as low as possible.

Side effects from stress medication are usually mild and short lived. These may include flushing, breathlessness, or headache, which settle quickly. Staff monitor you closely throughout the test.

If you have asthma, kidney problems, or other medical conditions, your cardiologist will consider this carefully before recommending the scan.

After the Scan

Once the scan is complete, you can usually return to normal activities the same day. Drinking fluids helps flush the tracer from your body.

A specialist reviews the images and prepares a detailed report. Your cardiologist will then explain the results and discuss what they mean for your symptoms and treatment plan.

You can contact us here to arrange a review or discuss whether a myocardial perfusion scan is appropriate for you.

Why Myocardial Perfusion Scans Are Valuable

Myocardial perfusion scans help doctors understand not just whether arteries are narrowed, but whether those narrowings affect heart muscle blood supply. This distinction is crucial when deciding on treatment.

The scan helps avoid unnecessary procedures while ensuring patients who need intervention receive it promptly. It also provides reassurance when results are normal.

Conclusion

A myocardial perfusion (MPS) scan is a detailed test that shows how well blood flows to the heart muscle at rest and during stress. It plays an important role in diagnosing coronary artery disease, assessing symptoms, and guiding treatment decisions.

At WKCP, we use myocardial perfusion scans as part of a careful, evidence based approach to heart care for patients across Kent and East Sussex. If you are experiencing chest pain, breathlessness, or have known heart disease, you can call us on 01892 526726 to discuss whether this test would be helpful for you.