Could tiny heart vessels hold the key to a common form of heart failure?

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

Inclusion Criteria: For the new cohort n=120 women undergoing coronary angiography: * Symptomatic angina or anginal equivalent * Age ≥ 18 * Participant is willing to give written informed consent For the cohort n=100 women and men hospitalized for HFpEF (defined by ESC guidelines): * Age ≥ 18 * Signs and symptoms of heart failure * Preserved ejection fraction, left ventricular ejection fraction (LVEF) ≥45% prior to study entry. * Structural evidence of cardiovascular abnormalities: elevated brain naturetic peptide, evidence of abnormal filling or relaxation, left ventricular hypertrophy, or an increased left atrial size * Evidence of elevated filling pressures: LVEDP or PCWP at rest \> 15 mmHg and/or with exercise ≥25 mmHg, exercise E/e' \>13, elevated BNP, or use of diuretic * Participant is willing to give written informed consent Exclusion Criteria: For the new cohort n=120 women undergoing invasive coronary angiography: * Obstructive CAD ≥ 50% luminal diameter stenosis in ≥ 1 epicardial coronary artery * STEMI within 3-7 days post MI, or Acute coronary syndrome/NSTEMI with with symptoms or signs of acute myocardial ischemia within the last 12 to 24 hours prior to the research procedure, as outlined in ACC/AHA guidelines. * Primary valvular heart disease clearly indicating the need for valve repair or replacement * Patients with concurrent cardiogenic shock or requiring inotropic or intra-aortic balloon support or LVEF\<45% * Prior or planned percutaneous coronary intervention or coronary artery bypass grafting for obstructive coronary atherosclerosis * Non-cardiac illness with a life expectancy \< four years * Unable to give informed consent * Chest pain which has an alternative non-ischemic etiology, i.e. pericarditis, pulmonary embolism, pleurisy, pneumonia, esophageal spasm, etc. * Contraindications to CMRI, such as internal cardiac defibrillator, untreatable claustrophobia or known angioedema * Contraindications to adenosine or regadenoson including severe COPD and asthma * End stage renal or liver disease * Women with intermediate coronary stenoses (\>20% but \<50% luminal diameter stenosis assessed visually at the time of angiography) will undergo clinically indicated fractional flow reserve (FFR) based on the judgment of the operator; those determined to have flow-obstructing stenosis will be excluded. * Documented allergy to gadolinium For the new cohort n=100 women and men hospitalized for HFpEF: * Current LVEF \<45% * STEMI within 3-7 days post MI, or Acute coronary syndrome/NSTEMI with with symptoms or signs of acute myocardial ischemia within the last 12 to 24 hours prior to the research procedure, as outlined in ACC/AHA guidelines. * Acute coronary syndrome (defined by ACC/AHA guidelines, including MI) within 3 months of entry. Patients who have had an MI or other event within the 6 months prior to entry unless an echo measurement performed after the event confirms a LVEF ≥45%. * Primary valvular heart disease (moderate regurgitation or\>mild stenosis), primary cardiomyopathies (hypertrophic, infiltrative or restrictive), constrictive pericarditis, high-output heart failure, and right ventricular myopathies) * Patients with concurrent cardiogenic shock or requiring inotropic or intra-aortic balloon support or current acute decompensated HF requiring therapy including due to trauma, infection. * Alternative reason for shortness of breath such as: significant pulmonary disease or severe COPD, hemoglobin (Hgb) \<10 g/dl, or body mass index (BMI) \> 40 kg/m2. * Systolic blood pressure (SBP) ≥ 180 mmHg at entry, or SBP \>150 mmHg and \<180 mmHg at entry unless the patient is receiving 3 or more antihypertensive drugs. * Prior or planned percutaneous coronary intervention or coronary artery bypass grafting for obstructive coronary atherosclerosis * Non-cardiac illness with a life expectancy \< four years * Unable to give informed consent * Contraindications to CMRI, such as internal cardiac defibrillator, untreatable claustrophobia or known angioedema * Contraindications to adenosine or regadenoson including severe COPD and asthma. * Obstructive stenoses (≥50% luminal diameter stenosis assessed visually at the time of research CTA) will be excluded from further analyses. Subjects with obstructive or borderline obstructive coronary CTA stenoses will be referred to their clinicians for further clinical care and clinical decision making. End stage renal or liver disease