Heart failure with improved ejection fraction (HFimpEF) describes a person who previously had heart failure with reduced ejection fraction, but whose heart-pumping measurement later improves.

Ejection fraction is the percentage of blood the left ventricle ejects with each contraction. A low EF reflects impaired systolic pumping function.

For example, someone whose EF was 30% during dilated cardiomyopathy and rises to 45% after treatment has HFimpEF. This is distinct from simply having an EF of 45% without a prior documented EF ≤40%. The ACC summary of the AHA/ACC/HFSA guideline uses this definition.

Why it happens Improvement may follow:

Key point: improved does not mean cured.
Even if symptoms resolve and EF normalizes, the underlying vulnerability often remains and heart failure can recur. Therefore, guidelines advise continuing the medications used for reduced-EF heart failure, if tolerated, rather than stopping them solely because EF has improved. This typically includes an ARNI/ACE inhibitor/ARB, evidence-based beta blocker, mineralocorticoid-receptor antagonist, and SGLT2 inhibitor when appropriate. The 2022 guideline specifically states that patients whose LVEF improves to >40% should continue HFrEF treatment.

Textbook context: partial EF recovery above 40% is common in chronic dilated cardiomyopathy with neurohormonal therapy and, when indicated, cardiac resynchronization therapy. Harrison’s Principles of Internal Medicine, 22e, section on heart failure.