Non-invasive Diagnosis of Coronary Microvascular Disease: Pilot Study

* 40% of patients presenting with stable chest pain (angina) have no significant blockage of the main heart arteries. Identifying why these patients have symptoms will mean better treatment options can be developed. * About 60% of these patients have evidence of coronary microvascular disease (CMD). In this condition there is a problem with the heart's microvessels (very small blood vessels that branch from the main heart arteries). Due to problems with these vessels there is a mismatch between the blood supply to the heart and its oxygen consumption, causing chest pain and this can also lead to major heart events. * At present, to diagnose this condition, specialised techniques during an invasive test, called a coronary angiogram, are required. As this is an invasive test, it can be lead to complications and cause discomfort. * Non-invasive ways of diagnosing CMD are required to improve the diagnosis and management of this condition. * This study aims to provide initial data on whether novel imaging techniques using CT and MRI scans, which are much less invasive, could identify CMD. * To do this, patients with suspected angina referred for angiography and who are already participants in the main research study 'CMR versus CT-FFR in CAD' study will be recruited. * These will be patients with suspected CMD and also those with blockage of the main heart arteries (triple vessel disease) to compare against. * Participants in this pilot study will have additional tests used to diagnose CMD during their invasive angiography procedure. Participants will then have an MRI scan involving novel techniques and exercise MRI, where individuals exercise use a cycle or stepping machine during the MRI scan. Further analysis will also be undertaken of CT images acquired as part of the main study. * These tests will be compared against invasive test results to see which show potential in being able to diagnose CMD.