The Value of Measuring Retinal Vascular Density by Optical Coherence Tomography-Angiography (OCT-A) in Patients With Microvascular Angina Confirmed by Myocardial Microcirculatory Resistance Index (MRI).

Microvascular angina is thought to affect around 112 million patients worldwide. However, this figure is underestimated due to the difficulty of making the diagnosis. It is a pathology caused by an alteration in the microcirculation of the heart muscle, which is not detectable on a standard coronary angiogram. In view of its prognostic, therapeutic and medico-economic value, scientific societies currently recommend invasive measurement of the microcirculatory resistance index (MRI) to diagnose microvascular angina, in the absence of significant lesions on coronary angiography. Several research teams, including our own, have shown that cardiovascular risk is associated with alterations in the vascularization of the small vessels (microcirculation) of the retina. Unlike the study of cardiac vessels, the study of retinal microcirculation using fundus photography (OCT-A) is simple, rapid, non-invasive and inexpensive. It appears to be an interesting alternative to the measurement of IMR for the diagnosis of microvascular angina. This hypothesis has never yet been tested. The demonstration of an association between a decrease in retinal vascular density measured by OCT-A and an alteration in coronary microvascular function measured by IMR would pave the way for a completely non-invasive diagnosis of patients. This is an observational, cohort, prospective, single-center pilot study comparing people who have received an IMR measurement as part of INOCA. It is planned to include 158 participants. The overall follow-up period for each patient in the research is 12 months. In routine care, IMR is measured during coronary angiography in patients presenting with ischemia on a non-invasive test and/or stress symptoms such as angina or dyspnea, for whom coronary angiography does not reveal any significant epicardial lesion. Following this examination, two groups will be formed: a group with an IMR\<25 and a group with an IMR≥25. Clinically, the study aims to determine the