Coronary microvascular dysfunction (CMD) is emerging as an important entity in the evaluation of patients with suspected ischemic myocardial syndromes. Observational data suggest that CMD is associated with increased risk of major adverse cardiovascular events, including heart failure with preserved ejection fraction (HFpEF),1 in a manner that is independent of conventional risk factors and ischemic or atherosclerotic disease burden2 and mediated by the presence of myocardial injury3 and left ventricular (LV) diastolic dysfunction.1 The combination of CMD and LV diastolic dysfunction is independently associated with a greater than 5-fold increased risk of future HFpEF hospitalization.1 Findings from a growing number of international studies using invasive4,5 or noninvasive6 functional testing support the premise that CMD is much more common than previously acknowledged, including in patients with HFpEF.7