Heart failure with reduced ejection fraction (HFrEF) 40 Also referred to as systolic HF. Randomized controlled trials have mainly enrolled patients with HFrEF, and it is only in these patients that efficacious therapies have been demonstrated to date. II. Heart failure with preserved ejection fraction (HFpEF) 50 Also referred to as diastolic HF. Several different criteria have been used to further define HFpEF. The diagnosis of HFpEF is challenging because it is largely one of excluding other potential noncardiac causes of symptoms suggestive of HF. To date, efficacious therapies have not been identified. a. HFpEF, borderline 41 to 49 These patients fall into a borderline or intermediate group. Their characteristics, treatment patterns, and outcomes appear similar to those of patients with HFpEF. b. HFpEF, improved >40 It has been recognized that a subset of patients with HFpEF previously had HFrEF. These patients with improvement or recovery in EF may be clinically distinct from those with persistently preserved or reduced EF. Further research is needed to better characterize these patients. EF indicates ejection fraction; HF, heart failure; HFpEF, heart failure with preserved ejection fraction; and HFrEF, heart failure with reduced ejection fraction. Table 4. Comparison of ACCF/AHA Stages of HF and NYHA Functional Classifications ACCF/AHA Stages of HF (37) NYHA Functional Classification (38) A At high risk for HF but without structural heart disease or symptoms of HF None B Structural heart disease but without signs or symptoms of HF I No limitation of physical activity. Ordinary physical activity does not cause symptoms of HF. C Structural heart disease with prior or current symptoms of HF I No limitation of physical activity. Ordinary physical activity does not cause symptoms of HF. II Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in symptoms of HF. 