What is a normal ejection fraction?

A normal left ventricular ejection fraction is generally 55% or higher. Values of 50-54% are considered borderline/low-normal.

How is ejection fraction calculated?

EF (%) = (End-Diastolic Volume − End-Systolic Volume) ÷ End-Diastolic Volume × 100. These volumes are typically measured by echocardiography (biplane Simpson's method), cardiac MRI, or nuclear imaging.

What is HFrEF, HFmrEF, and HFpEF?

These are 2022 ACC/AHA/HFSA heart failure classifications based on ejection fraction: HFrEF (reduced) is EF ≤40%, HFmrEF (mildly reduced) is EF 41-49%, and HFpEF (preserved) is EF ≥50%, each with somewhat different treatment emphasis.

What EF qualifies for an ICD?

EF ≤35% despite at least 3 months of optimized guideline-directed medical therapy is a standard threshold for primary prevention implantable cardioverter-defibrillator (ICD) candidacy in appropriate patients.

Can ejection fraction improve with treatment?

Yes. Guideline-directed medical therapy can meaningfully improve EF over months, sometimes normalizing it entirely (HFimpEF, improved EF) — but evidence shows these patients should generally continue GDMT indefinitely, since stopping treatment commonly causes relapse.

Is a normal ejection fraction enough to rule out heart failure?

No. Heart failure with preserved ejection fraction (HFpEF) is common, especially in older adults, women, and patients with hypertension, obesity, or diabetes — a normal EF doesn't exclude heart failure when symptoms and other supporting findings (elevated natriuretic peptides, diastolic dysfunction) are present.

What causes a reduced ejection fraction?

Common causes include ischemic cardiomyopathy (from prior heart attacks), non-ischemic dilated cardiomyopathy, uncontrolled hypertension, valvular heart disease, chronic arrhythmias (tachycardia-induced cardiomyopathy), viral myocarditis, chemotherapy-related cardiotoxicity, and peripartum cardiomyopathy.

How accurate is echocardiography for measuring EF?

2D echo with biplane Simpson's method is generally accurate but relies on geometric assumptions and image quality; cardiac MRI is considered the more accurate and reproducible gold-standard reference method, particularly useful when EF is borderline near a treatment-changing threshold.

Heart failure with improved ejection fraction — a 2022 ACC/AHA/HFSA category for patients with previously reduced EF (≤40%) that has improved to above 40% with a ≥10-point increase from baseline following treatment. These patients should generally continue GDMT indefinitely.

Does ejection fraction predict prognosis?

Yes, generally — lower EF is associated with higher risk of hospitalization, arrhythmia, and mortality, though HFpEF also carries substantial morbidity and mortality risk despite a normal EF, so EF alone is not a complete prognostic picture.

Online Medical Tools — Ejection Fraction

Printed on 9/3/2026

For informational purposes only. This is not medical advice.

Cardiology

Ejection Fraction

Ejection fraction (EF) is the percentage of blood the left ventricle ejects with each contraction, and it's the single most-used metric for classifying heart failure type and guiding therapy selection. This calculator uses the volumetric formula (EDV − ESV) ÷ EDV, matching what echocardiography, cardiac MRI, and nuclear imaging report. Combine with the ACC/AHA Heart Failure Staging to place a patient's overall HF trajectory, and with Cardiac Output to distinguish a pure pump-function problem from a volume/rate problem. Assess cardiovascular risk more broadly with ASCVD Risk and NYHA Functional Class for symptom staging.

Formula: EF (%) = (EDV − ESV) ÷ EDV × 100

LV End-Diastolic Volume (EDV)

LV End-Systolic Volume (ESV)

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How It Works

Obtain end-diastolic and end-systolic left ventricular volumes

Ejection fraction requires two volume measurements of the left ventricle: end-diastolic volume (EDV), the LV volume at maximum filling just before contraction, and end-systolic volume (ESV), the LV volume remaining just after contraction. These are most commonly obtained from echocardiography using the biplane Simpson's method (tracing the endocardial border in two apical views), though cardiac MRI is considered the gold-standard reference method due to its superior accuracy and reproducibility, and nuclear imaging (MUGA scan, gated SPECT) and left ventriculography during cardiac catheterization are also used in specific clinical scenarios. The stroke volume (the amount of blood ejected per beat) is simply EDV minus ESV — this is the same stroke volume value used in cardiac output calculations, connecting ejection fraction to overall hemodynamic assessment.

Calculate the ejection fraction percentage

Ejection Fraction (%) = (EDV − ESV) ÷ EDV × 100. For example, an EDV of 120 mL and ESV of 50 mL gives a stroke volume of 70 mL and an ejection fraction of 58.3% — within the normal range. This formula expresses ejection fraction as the fraction of the ventricle's total diastolic volume that gets ejected with each beat, which is why it's a percentage rather than an absolute volume — a dilated ventricle with a large stroke volume can still have a reduced ejection fraction if its end-diastolic volume is proportionally even larger.

Classify using 2022 ACC/AHA/HFSA heart failure categories

The 2022 ACC/AHA/HFSA Heart Failure Guideline defines four EF-based categories that directly drive treatment decisions: HFrEF (heart failure with reduced ejection fraction, EF ≤40%) — the category with the strongest evidence base for GDMT (ACE-I/ARB/ARNI, beta-blocker, MRA, SGLT2 inhibitor — the 'four pillars'); HFmrEF (mildly reduced, EF 41-49%) — increasingly treated with similar GDMT to HFrEF based on more recent trial evidence; HFpEF (preserved, EF ≥50%) — where SGLT2 inhibitors are now the primary evidence-based therapy, with management otherwise focused on comorbidities (hypertension, obesity, atrial fibrillation); and HFimpEF (improved, previously reduced EF that has recovered to >40% with a ≥10-point increase) — a category recognizing that these patients still need to continue GDMT despite the improved number, since stopping therapy commonly causes relapse. A normal EF (≥55%) in a patient without heart failure symptoms doesn't require any specific heart-failure-directed therapy, though the underlying cause of any structural changes (hypertension, valve disease) should still be addressed.

Who Uses the Ejection Fraction

New Heart Failure Diagnosis and Classification

Cardiologists and hospitalists diagnosing HF

Calculate or confirm EF from the echo report to correctly classify a newly diagnosed heart failure patient into HFrEF, HFmrEF, or HFpEF — the single most important branch point for selecting guideline-directed medical therapy.

GDMT Initiation and Titration Decisions

Cardiologists and primary care managing chronic HF

EF classification directly determines which of the four GDMT pillars have strong trial evidence for a given patient, and tracking EF over serial echocardiograms shows whether therapy is achieving reverse remodeling.

Device Therapy Eligibility (ICD/CRT)

Electrophysiologists evaluating device candidacy

EF ≤35% despite optimized GDMT for at least 3 months is a key threshold for primary prevention implantable cardioverter-defibrillator (ICD) eligibility, and EF ≤35% with wide QRS is central to cardiac resynchronization therapy (CRT) candidacy.

Preoperative Cardiac Risk Assessment

Anesthesiologists and surgeons evaluating surgical candidates

A reduced EF is an independent risk factor for perioperative cardiac complications and informs decisions about preoperative optimization, monitoring intensity, and anesthetic approach for major surgery.

Cardio-Oncology Surveillance

Cardio-oncology teams monitoring chemotherapy patients

Serial EF monitoring during and after cardiotoxic chemotherapy (anthracyclines, trastuzumab) detects early cardiotoxicity — a drop of ≥10 percentage points to a value below 53% is a common threshold triggering cardioprotective intervention or chemotherapy modification.

Pro Tips

A single EF value doesn't distinguish cause — always pair with clinical context

A reduced EF can result from ischemic cardiomyopathy, non-ischemic dilated cardiomyopathy, valvular disease, tachycardia-induced cardiomyopathy, or peripartum cardiomyopathy, among others — the number alone doesn't tell you the etiology, which is essential for both prognosis and treatment beyond standard GDMT.

HFmrEF patients often respond to the same GDMT as HFrEF

Subgroup analyses of major HF trials (and more targeted contemporary trials) show that patients in the 41-49% range generally benefit from the same four-pillar GDMT approach as HFrEF, which is why the 2022 guidelines grouped their treatment recommendations more closely than earlier classifications did.

HFimpEF patients need to stay on GDMT even after EF normalizes

The TRED-HF trial and subsequent evidence show that patients whose EF recovers with treatment (HFimpEF) commonly relapse if GDMT is withdrawn — improved EF reflects successful treatment, not cure, and therapy should generally continue indefinitely absent a strong reason to stop.

Different imaging modalities can report meaningfully different EF values for the same patient

Cardiac MRI is generally considered more accurate and reproducible than 2D echo (which relies on geometric assumptions), and can report an EF several percentage points different from a same-day echo. When EF is borderline near a treatment-changing threshold (e.g., 34% vs 36% for ICD eligibility), consider confirming with a second modality.

EF can be technically difficult to measure accurately in certain patients

Poor acoustic windows (obesity, COPD), irregular rhythms (atrial fibrillation causing beat-to-beat volume variability), and foreshortened apical views all reduce measurement reliability on 2D echo — 3D echo or cardiac MRI can be considered when accuracy is critical and initial imaging quality is suboptimal.

EF ≥55% doesn't rule out heart failure — consider HFpEF

A substantial proportion of heart failure patients, particularly older adults, women, and those with hypertension, diabetes, or obesity, have heart failure with preserved ejection fraction — normal EF does not exclude heart failure when symptoms and other objective evidence (elevated natriuretic peptides, diastolic dysfunction, structural changes) are present.

Common Questions About Your Results

No — this is a common and important misconception. This patient now falls into the HFimpEF (improved EF) category, and evidence strongly suggests continuing GDMT indefinitely, since withdrawal commonly leads to relapse of both symptoms and reduced EF. The improvement reflects that the treatment is working, not that the underlying cardiomyopathy has resolved. Continue all four GDMT pillars unless there's a specific contraindication that has developed.

Ranges are common when the echocardiographer uses visual/qualitative 'eyeballing' assessment rather than formal biplane Simpson's tracing, or when image quality limits precision. When a range spans a treatment-relevant threshold (like 45-50%, spanning HFmrEF and HFpEF), it's reasonable to request a repeat study with formal volumetric tracing, or consider cardiac MRI for a more precise number if the classification will change management meaningfully.

Yes — this is exactly the HFpEF (heart failure with preserved ejection fraction) scenario, where the ventricle contracts normally but has impaired relaxation and filling (diastolic dysfunction), or where symptoms arise from a combination of comorbidities (obesity, atrial fibrillation, hypertension, pulmonary hypertension) rather than a primary EF-reducing process. A normal EF should never be used alone to exclude a heart failure diagnosis when the clinical picture and natriuretic peptide levels suggest otherwise.

Not necessarily — some patients have asymptomatic (or 'Stage B') reduced EF, sometimes discovered incidentally, without ever developing overt heart failure symptoms, particularly with prompt GDMT initiation. However, reduced EF is a significant risk factor for eventual symptomatic progression, arrhythmia, and mortality, which is why GDMT is recommended even in asymptomatic patients with EF ≤40%.

Clinical Content Trust

Last reviewed:: April 21, 2026
Guideline version:: General evidence framework v2026.04
Source set version:: Primary-source set v1

How to Interpret Your Result

EF ≥55% is normal, 50-54% is borderline, 41-49% is HFmrEF, and ≤40% is HFrEF per 2022 ACC/AHA/HFSA criteria. Classification directly determines which guideline-directed medical therapies have the strongest evidence base for a given patient.

When to Use This Tool

Use whenever LV end-diastolic and end-systolic volumes are available from echocardiography, cardiac MRI, or nuclear imaging, to calculate or confirm ejection fraction and classify heart failure type for treatment planning.

Limitations

Accuracy depends on imaging quality and modality — 2D echo relies on geometric assumptions and can be affected by poor acoustic windows or irregular rhythms. A normal EF does not exclude heart failure (HFpEF), and EF alone does not indicate the underlying etiology of cardiomyopathy.

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.

Changelog

April 21, 2026 · trust-baseline
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