It has been nearly 30 years since the first series of patients with the syndrome of heart failure with a preserved ejection fraction (HFpEF) was reported.1 It has proven to be a controversial topic. Because left ventricular (LV) EF is preserved, it was assumed that HFpEF results from altered diastolic properties. However, some argued that these patients did not truly have HF or had subtle forms of dilated HF. Symptomatic of this debate is reluctance to use the term diastolic HF (we prefer HFpEF because diastolic dysfunction is also present in HF with a reduced EF) as well as disagreement over the exact EF cutoff, that is, should a perfectly normal EF be required to diagnose HFpEF or does a modest reduction qualify? Article see p 1239 Although many questions remain, in the intervening years several features have emerged. HFpEF is a complex and extremely common syndrome, accounting for >50% of patients with HF.2–6 It is more prevalent in women, and its prognosis is similar to HF with a reduced EF. The clinical presentation ranges from dyspnea with physical activity to a pattern of restrictive cardiomyopathy, with marked elevations of right and left filling pressure at rest, often with considerable pulmonary hypertension (HTN). Essentially all patients with HFpEF have diastolic dysfunction,7 specifically, reduced LV passive compliance and/or slowed or incomplete relaxation. Various other cardiovascular abnormalities are common,3–6 including subtle abnormalities of systolic function. Although a small number of patients have HFpEF in association with specific cardiac diagnoses, for example, hypertrophic and infiltrative cardiomyopathy, constrictive pericarditis, all of which have profound effects on diastolic compliance, the vast majority have a history of HTN.3,4,8 In many patients, especially elderly women, HTN is exclusively systolic,9 resulting from reduced arterial …