Abstract
IntroductionAngina with no obstructive coronary artery disease (ANOCA) is a common syndrome with unmet clinical needs. Microvascular and vasospastic angina are relevant but may not be diagnosed without measuring coronary vascular function. The relationship between cardiovascular magnetic resonance (CMR)-derived myocardial blood flow (MBF) and reference invasive coronary function tests is uncertain. We hypothesise that multiparametric CMR assessment will be clinically useful in the ANOCA diagnostic pathway.Methods/analysisThe Stratified Medical Therapy Using Invasive Coronary Function Testing In Angina (CorMicA) trial is a prospective, blinded, randomised, sham-controlled study comparing two management approaches in patients with ANOCA. We aim to recruit consecutive patients with stable angina undergoing elective invasive coronary angiography. Eligible patients with ANOCA (n=150) will be randomised to invasive coronary artery function-guided diagnosis and treatment (intervention group) or not (control group). Based on these test results, patients will be stratified into disease endotypes: microvascular angina, vasospastic angina, mixed microvascular/vasospastic angina, obstructive epicardial coronary artery disease and non-cardiac chest pain. After randomisation in CorMicA, subjects will be invited to participate in the Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) substudy. Patients will undergo multiparametric CMR and have assessments of MBF (using a novel pixel-wise fully quantitative method), left ventricular function and mass, and tissue characterisation (T1 mapping and late gadolinium enhancement imaging). Abnormalities of myocardial perfusion and associations between MBF and invasive coronary artery function tests will be assessed. The CorCMR substudy represents the largest cohort of ANOCA patients with paired multiparametric CMR and comprehensive invasive coronary vascular function tests.Ethics/disseminationThe CorMicA trial and CorCMR substudy have UK REC approval (ref.16/WS/0192).Trial registration numberNCT03193294.
Highlights
Angina with no obstructive coronary artery disease (ANOCA) is a common syndrome with unmet clinical needs
What does this study add? ►► Novel cardiovascular magnetic resonance (CMR) methods for measuring myocardial blood flow have not been validated in patients with ANOCA and underlying microvascular and vasospastic angina. ►► The Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) substudy represents the largest cohort of ANOCA patients with paired multiparametric CMR and comprehensive invasive coronary vascular function tests
Assessment of microvascular resistance (IMR), microvascular vasodilatory capacity (resistance reserve ratio (RRR)), epicardial and microvascular vasodilatory capacity (CFR), endothelial function and epicardial coronary artery disease (CAD) (fractional flow reserve (FFR)) will be performed. Following these invasive tests of coronary artery function, patients will be classified into the following ANOCA disease endotypes: (1) microvascular angina; (2) vasospastic angina; (3) mixed microvascular angina and vasospastic angina; (4) obstructive epicardial CAD; and (5) non-cardiac chest pain
Summary
Ischaemic heart disease is the leading cause of mortality standardised by age and sex.[1]. Microvascular vasodilatory capacity (CFR), endothelial function (acetylcholine provocation testing) and epicardial CAD (fractional flow reserve (FFR)) will be performed Following these invasive tests of coronary artery function, patients will be classified into the following ANOCA disease endotypes (table 1): (1) microvascular angina; (2) vasospastic angina; (3) mixed microvascular angina and vasospastic angina; (4) obstructive epicardial CAD; and (5) non-cardiac chest pain. The CorCMR substudy of the CorMicA clinical trial presents a unique opportunity to assess and validate the diagnostic accuracy of fully quantitative stress perfusion CMR in patients with ANOCA and comprehensive invasive coronary artery function testing. The diagnostic accuracy of the perfusion CMR metrics for abnormal invasive tests of coronary artery function (IMR >25, CFR
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