Coronary Microvascular Function and CT Coronary Angiography (CorCTCA)

Angina in patients without obstructive coronary artery disease (CAD) is a clinical conundrum and patient management is heterogeneous. Hypothesis: Abnormal coronary function is common and clinically relevant in this population. Design: An observational cohort study and nested randomised controlled diagnostic strategy trial. Methods: 250 patients with known or suspected angina informed by validated questionnaires but without obstructive CAD (\=2.5 mm or structural heart disease, as revealed by CT coronary angiography (CTCA), will be invited to undergo coronary function testing (FFR, CFR, IMR; intra-coronary ACh) during invasive angiography. Patients will be randomised following angiography but before testing coronary function to disclosure of the coronary function test results or not. Treatment decisions by the attending cardiologist will be recorded before and after disclosure of results. Outcomes: Primary: The between-group difference in the reclassification rate of the initial diagnosis using logistic regression, adjusted for baseline factors associated with the likelihood of reclassification of the initial diagnosis. Secondary: Prevalence of microvascular or vasospastic angina; health status reflected by the EuroQol group 5-Dimensions (EQ-5D), Seattle Angina Questionnaire, Illness perception, treatment satisfaction questionnaires and functional status questionnaires; angina medication and adherence. Value: This research will provide new insights into the conundrum of angina in patients without obstructive CAD or structural heart disease.