The study is designed as prospective registry. Patients with angina CCS II-IV undergoing assessment of microvascular function will be enrolled.~The study does not interfere with the medical standards at the sites with regards to patient treatment or follow-up care.~Study duration and schedule The duration of this study is expected to be 7 years. The subject recruitment is planned to start in January 2020 and end in January 2022. The actual overall study duration or subject recruitment period may differ from these time periods. Per-patient, the duration of participation will be up to 5 years. Patients will be evaluated at hospital discharge, at 12 months and 5 years (the latter two as telephone contacts).~Number of subjects and study centers It is planned to enroll 1000 subjects in the registry based on power calculations as described. Recruitment and treatment of subjects is expected to be performed in 10 study centers.~Primary endpoint The primary endpoint is the composite of cardiovascular death, myocardial infarction, rehospitalization for angina or heart failure, and unplanned coronary angiography at 12 months.~Secondary endpoints Each of the components of the primary endpoint Seattle Angina Questionnaire SAQ-7 Physical limitation scale SAQ-7 angina stability scale SAQ-7 angina frequency scale SAQ-7 angina quality of life EQ-5D-5L Beck depression inventory~The SAQ-7 angina frequency domain has been shown to correlate to improvements in microvascular function in the WISE study. SAQ-7-7 has been also used in a number of studies, including the ISCHEMIA study.~Other patient questionnaires are also standardized tests for the assessment of quality of life, depression and symptom severity in coronary artery disease studies.
The evidence above demonstrates that microvascular dysfunction is an important determinant of patient prognosis, which however remains poorly classified. Given the high burden of disease and the severity of the functional impairment in these patients, the lack of a clear definition for this disease has a potentially large clinical importance. It is important to better describe the phenotype of these patients, identify the predictors of prognosis, and determine the impact of diagnosis.