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What is microvascular angina?

I have been diagnosed with microvascular angina. Please can you explain what this is? Is there any research happening to help people like me?

Professor Colin Berry replies: 

Angina is a symptom triggered by a lack of blood supply to the heart. Usually, doctors look at angina in terms of finding blockages in the main heart arteries, followed by treatments including drugs, stents or bypass surgery

However, nearly half of all coronary angiograms do not reveal any blockages in blood vessels. Sometimes this is because the problem is not heart-related, but sometimes this is because these genuine symptoms are caused by microvascular angina. It refers to disease in the small blood vessels, less than half a millimetre across and therefore too small to be detected using standard tests like angiogram.

Microvascular angina refers to disease in the small blood vessels, less than half a millimetre across

Research from our group and by others in the UK and abroad indicates that small vessel problems may affect at least one third of patients with angina but who have clear heart arteries.

Our aim is to clarify the basis of this health problem, which historically has been a frustrating enigma to diagnose and treat and is still known to some as ‘cardiac syndrome X’.

Imagine a tree and its branches. The main heart artery is the tree trunk and the many small branches and twigs are like the small vessels in the heart. Imaging tests can show the main trunk and branches, but the smaller branches and twigs are invisible to the human eye.

Diagram of microvascular angina, showing the coronary artery and microcirculation

Diagnosing microvascular angina

Research in the UK and abroad has confirmed that patients with microvascular angina are at risk of being admitted to hospital and even experiencing a heart attack

But in the past, small vessel problems in the heart have been very difficult to diagnose. Now, enabled by technological advances, we and other groups are assessing the value of new tests of small vessel function in the heart. These include:

  • Using small guidewires, about the thickness of a human hair, passed into a coronary artery during an angiogram in order to measure blood vessel function. 
  • A test using a drug called acetylcholine, and
  • New advances with MRI scans that allow heart muscle blood flow to be measured quickly.

Another possible reason for angina when the heart arteries appear to be clear can be temporary spasms of the heart arteries – this is called coronary artery spasm, or sometimes vasospastic angina or Prinz metal angina.

Current microvascular angina research

The new tests for small vessel function in the heart are not yet standard in the NHS, mainly because there has never been clear evidence gathered about whether treatment decisions informed by the results of these tests would lead to patient benefits. We’re currently running the ‘proof-of-concept’ CorMicA trial in Glasgow, supported by the BHF, to gather evidence to properly answer this question for the first time. 

There are gaps in knowledge about why microvascular angina happens. High blood pressure may be involved for some, but not all, patients. Changes in the hormones, and genetic influences, may also be involved, but we don’t have all the answers yet.

Our research aims to determine whether routine use of new blood vessel tests might help detect sub-groups of patients with angina due to small vessel disease. This approach is called ‘stratified medicine’. Our aim is to personalise medicine to get the right tests and treatments to the right patients at the right time.

Our aim is to personalise medicine to get the right tests and treatments to the right patients at the right time

We are actively studying the underlying causes of small vessel disease in the hearts of individual patients with a view to making personalised treatment decisions that are linked to the underlying problem. 

With colleagues in Mathematics and Statistics based in Glasgow, we are developing computer-based techniques to develop virtual models of blood flow in the heart. These are intended to be useful in predicting how a new drug might be beneficial, overall, and also to allow personalised medicine in individual patients.

To this end, researchers in Glasgow, and other groups in the UK and abroad are actively working to develop new medicines to specifically help patients with microvascular angina and coronary artery spasm.

We also aim to develop new tests using a blood and/or urine sample to help diagnose the cause of chest pain in individual patients in the clinic. The tests should be helpful to doctors and may help avoid a specialised heart scan that may be inconvenient and expensive.

Professor Colin BerryMeet the expert

Professor Colin Berry is Chair in Cardiology and Imaging in the University of Glasgow,  Director of Research and Development and Consultant Cardiologist at the Golden Jubilee National Hospital, and Consultant Cardiologist at the Queen Elizabeth University Hospital in Glasgow. 

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