Comprehensive Assessment of Myocardial Ischemia Mechanisms in the Catheterization Laboratory: Design and Rationale of the Advanced Invasive Diagnosis Strategy for Patients with Stable Coronary Syndromes Undergoing Coronary ANGIOgraphy - the AID-ANGIO Study.

BACKGROUND: The diagnostic yield of invasive coronary angiography (ICA) to identify obstructive coronary artery disease in the context of chronic coronary syndromes (CCS) is very low. Furthermore, myocardial ischemia may have a non-obstructive origin, which cannot be detected by ICA. METHODS: AID-ANGIO is an observational, prospective, single-cohort, multicenter study, intended to evaluate the diagnostic yield of adopting a hierarchical strategy to assess obstructive and non-obstructive causes of myocardial ischemia in an all-comers population of patients with CCS at the time of ICA. The primary endpoint will investigate the additional diagnostic value of such strategy over angiography alone regarding the identification of ischemia-generating mechanisms. SUMMARY: An estimated sample of consecutive 260 patients with CCS referred by their clinicians to ICA, will be enrolled. In a stepwise manner, a conventional ICA will be performed as the initial diagnostic tool. Those patients with severe-grade stenosis will not undergo further assessment and an obstructive origin for myocardial ischemia will be assumed. Subsequently, the remainder with intermediate-grade stenosis will be assessed with pressure guidewires. Those with a negative result from physiological evaluation and those without epicardial coronary stenosis will be further studied for ischemia of non-obstructive origin, including microvascular dysfunction and vasomotor disorders. The study will be conducted in two steps. Firstly, ICA images will be displayed to patient's referring clinicians, who will be asked to identify the existent epicardial stenosis, their angiographic severity and probable physiological relevance, together with a tentative therapeutic approach. Then, the diagnostic algorithm will continue to be applied and, considering the whole gathered information, a definite therapeutic plan will be consensually established by the interventional cardiologist and patient's referring clinicians. CONCLUSION: The AID-ANGIO study will assess the additional diagnostic yield of a hierarchical strategy over ICA alone to identify ischemia-generating mechanisms in patients with CCS and its impact on therapeutic approach. Positive results of the study might support a streamlined invasive diagnostic process for patients with CCS.