Primary and secondary HFpEF. The exact prevalence of HFpEF is unknown. It is estimated at approximately 40% of patients with heart failure (HF) have reduced EF% (LVEF ≤40%), 20% have LVEF between 40% and 49%, and the remaining have preserved left ventricular ejection fraction (LVEF ≥50%) or HFpEF. Patients with HFpEF can be distinguished in 2 subgroups based on whether a specific cause can be identified or not. Secondary causes of HFpEF include valvular heart disease, hypertrophic cardiomyopathy, restrictive/infiltrative cardiomyopathies, constrictive pericarditis and other conditions. Primary HFpEF refers to a condition in which a primary impairment in myocardial relaxation or compliance exists. The prevalence of HFpEF in its primary and secondary forms is not represented in epidemiological scale. HF = heart failure; HFmEF: HE with mid-range ejection fraction; HFpEF = HF with preserved ejection fraction; HFrEF = HF with reduced ejection fraction.