Mystery chest pain: study digs deeper to find hidden heart problems

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Suspected ischemic heart disease and is referred to undergo clinically indicated invasive coronary angiography * No obstructive coronary artery disease (CAD) as defined by operator visual assessment with (1) angiographically normal coronary arteries OR (2) non-obstructive CAD with angiographic stenosis \< 50%, or greater than or equal to 50 but \< 70% with FFR greater than or equal to 0.81 or RFR greater than or equal to 0.90 * Willing to comply with specified follow-up evaluations. The participant or legally authorized representative has been informed of the nature of the study, agrees to its provisions, and has been provided written informed consent approved by the appropriate Institutional Review Board (IRB) or Ethics Committee (EC) Exclusion Criteria: * Pregnant or nursing * Any myocardial infarction at index presentation or within 90 days prior to enrollment, defined as any electrocardiogram diagnostic for myocardial infarction OR elevation in serum troponin greater than the upper limit of the site-defined reference range * Known left ventricular ejection fraction \< 50% or cardiogenic shock requiring pressors or mechanical circulatory assistance (e.g., intra-aortic balloon pump, left ventricular assist device, other temporary cardiac support blood pump) * Renal insufficiency, defined as estimated glomerular filtration rate (eGFR) \<30 mL/min/1.73 m2 (by the Modification of Diet in Renal Disease equation) or dialysis at the time of screening * Prior percutaneous coronary intervention * Planned percutaneous coronary intervention (PCI) * Prior coronary artery bypass graft surgery * Prior ST-elevation myocardial infarction * History of hypertrophic cardiomyopathy * History of infiltrative heart disease (e.g., cardiac amyloidosis) * New York Heart Association Class IV congestive heart failure * Severe mitral regurgitation * Severe aortic stenosis * Severe pulmonary hypertension (Mean pulmonary artery pressure greater than or equal to 35mmHg or echocardiographic right ventricular systolic pressure greater than or equal to 60mmHg) * Known history of unrepaired or repaired congenital heart disease * Past or pending heart transplant, or on the waiting list for organ transplant * Known other medical illness or known history of substance abuse that may cause non-compliance with the protocol, or is associated with a life expectancy of less than 1 year * Current or planned participation in a study of an investigational therapy * Angiographic stenosis in any major epicardial vessel ≥ 70% by visual estimate * Angiographic stenosis in any major epicardial vessel greater than or equal to 50% and \< 70% by visual estimate with FFR less than or equal to 0.80 or RFR less than or equal to 0.89