Among patients with chronic heart failure, those with a left ventricular ejection fraction (LVEF) ≤40% are considered to have heart failure with reduced ejection fraction (HFrEF). Patients with a LVEF ≥50% are considered to have heart failure with preserved ejection fraction (HFpEF). Those with a LVEF of 41-49% are an intermediate group more similar to patients with HFpEF.