International prospective cohort study of microvascular angina - Rationale and design.

Background: Patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery disease (CAD) frequently have coronary functional abnormalities, including coronary microvascular dysfunction. Those with the latter are grouped under the term "microvascular angina" (MVA). Although diagnostic criteria exist for MVA, as recently proposed by our COVADIS (COronary VAsomotor Disorders International Study) group and the condition has been increasingly recognized in clinical practice, the clinical characteristics and long-term prognosis of MVA patients in the current era remain to be fully elucidated.

Aims: In the present study, we aimed to prospectively assess the clinical characteristics and long-term prognosis of MVA subjects in the current era in an international, multicenter, observational, and prospective registry study.

Methods: A total of 15 medical centers across 7 countries (USA, UK, Germany, Spain, Italy, Australia, and Japan) enrolled subjects fulfilling the COVADIS diagnostic criteria for MVA as follows; (1) signs and/or symptoms of myocardial ischemia, (2) absence of obstructive CAD, and (3) objective evidence of myocardial ischemia and/or coronary microvascular dysfunction. The primary endpoint was the composite of major cardiovascular events (MACE), including cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, hospitalization due to heart failure or unstable angina. Between July 2015 and December 2018, a total of 706 subjects with MVA (M/F 256/450, 61.1 ± 11.8 [SD] yrs.) were registered. Subjects will be followed for at least 1 year.

Summary: The present study will provide important information regarding the clinical characteristics, management, and long-term prognosis of MVA patients in the current era.