Trial helps determine underlying causes of angina

An intensive study into the treatment of angina has found that the use of tests for small blood vessel function in the heart clarify the underlying cause of the condition.

Patients referred to hospital by their General Practitioner (GP) for assessment of chest pain were invited into the study if a heart scan had ruled out blocked heart arteries.

The trial showed that the common underlying cause of chest symptoms in angina sufferers was myocardial ischemia with no obstructive arteries (INOCA), which wasn't diagnosed by a standard CT heart scan.

The diagnosis was clarified using the tests where INOCA was four times more likely, while "normal" results were half as less likely to detect small vessel disease.

The study was carried out by heart specialists from the University of Glasgow and took place in three hospitals within NHS Scotland—the Golden Jubilee University National Hospital in Clydebank, Glasgow Royal Infirmary and Forth Valley Royal Hospital in Larbert, Falkirk.

One of the trial's leads, Professor Colin Berry—a Cardiology Consultant at NHS Golden Jubilee and Chair in Cardiology and Imaging at the University of Glasgow said, "In patients experiencing angina in the community, it is not known whether INOCA is a common cause of angina and, in addition, if it is diagnosed, the treatment of INOCA is also uncertain.

"We assessed whether the addition of tests of small vessel function might change the diagnosis based on the CT scan and, if so, would changes in treatment lead to improvements of symptoms, health-related quality of life, satisfaction with care and onward referrals for medical care.

"In terms of clinical implications, the trial results show that use of these tests will help to answer what patients regularly ask—'What is the cause of my chest pain?' We found that this approach led to improvements in treatment satisfaction, reduced unnecessary referrals for extra tests and helped to improve control of blood pressure."

Professor Berry believes more research is needed to develop new medicines for small vessel disease in the heart. He added, "To this end, our team is currently leading the PRIZE trial, funded by the Medical Research Council, which is scheduled to report results towards the end of 2023.

"We would like to thank the patients and the staff who supported this study, the study sponsor and the funders—the British Heart Foundation and the Chief Scientist Office of the Scottish Government."

Members of the team who carried out the trial presented the findings at the cardiovascular medicine conference, EuroPCR, in Paris on Thursday 18 May.