What is the clinical significance of a left ventricular ejection fraction of 50% and what assessment and management steps are recommended?

Ejection Fraction of 50%: Clinical Significance and Management

Classification and Immediate Interpretation

An ejection fraction of exactly 50% represents the lower threshold of normal left ventricular systolic function and warrants careful clinical assessment to determine if the patient has heart failure and to identify any underlying cardiac pathology. 1, 2

• Normal LVEF is defined as 50-70% (midpoint 60%) by the American College of Cardiology/American Heart Association, with the European Society of Cardiology citing a reference range of 53-73% (mean 63 ± 5%) 2
• An EF of exactly 50% sits at the boundary: it meets criteria for preserved EF (HFpEF ≥50%) but represents the lowest end of normal function 1, 2
• This borderline value requires serial measurements rather than relying on a single assessment, as EF varies between imaging modalities, interpreters, and clinical states 2, 3

Critical Diagnostic Considerations

Determine if Heart Failure is Present

The presence of an EF of 50% alone does not establish or exclude heart failure. You must assess:

• Clinical symptoms and signs: breathlessness, fatigue, ankle swelling, elevated jugular venous pressure, pulmonary crackles, peripheral edema 3
• Elevated natriuretic peptides: BNP >35 pg/mL or NT-proBNP >125 pg/mL support a heart failure diagnosis 1, 3
• Echocardiographic evidence of diastolic dysfunction: E/e′ ≥15, elevated filling pressures, increased left atrial volume index, or increased LV mass index 1, 3

Recognize the Dynamic Trajectory

A single EF measurement of 50% is inadequate for clinical decision-making because patients at this threshold exist on a dynamic trajectory—either improving from reduced EF or deteriorating toward it. 1, 3

• If the patient previously had EF <40% and now measures 50%, this represents heart failure with improved EF (HFimpEF) and the patient should continue HFrEF-directed therapy (ACE inhibitors/ARBs, beta-blockers, mineralocorticoid receptor antagonists, SGLT2 inhibitors) to prevent relapse 1
• If the patient is deteriorating from a higher EF, serial measurements are essential to detect progression toward HFmrEF (41-49%) or HFrEF (≤40%) 1, 3

Assessment Algorithm

Step 1: Verify Measurement Quality

• Confirm the EF was measured using the biplane method of discs (modified Simpson's rule) from apical four-chamber and two-chamber views, which is the recommended technique 2
• Avoid linear measurement methods (Teichholz, Quinones) that rely on geometric assumptions and are unreliable in abnormally shaped ventricles 2
• Consider 3D echocardiography if available, as it is more accurate than 2D methods 2

Step 2: Assess for Confounding Factors

Load-dependent conditions can artificially affect EF measurements:

• Hypovolemia or dehydration can artificially elevate EF 2
• Small ventricular cavity may produce artificially high calculations 2
• Reduced afterload (e.g., mitral regurgitation) can mask systolic dysfunction 2
• Atrial fibrillation or tachycardia make measurements less reliable—average multiple cardiac cycles 2

Step 3: Identify Underlying Etiology

Aggressively evaluate for the cause of borderline systolic function: 3

• Ischemic heart disease: coronary angiography or stress testing if indicated
• Valvular disease: assess for aortic stenosis, aortic regurgitation, or mitral regurgitation 4
• Hypertension: particularly systolic hypertension in elderly patients 5
• Cardiomyopathy: dilated, hypertrophic, or restrictive patterns

Step 4: Consider Advanced Functional Assessment

When EF is borderline but dysfunction is suspected, assess global longitudinal strain (GLS): 2

• GLS <-16% indicates mild depression of systolic function 2
• GLS <-10% indicates severe reduction 2
• GLS detects subclinical LV dysfunction before EF impairment and is highly feasible and reproducible 2

Management Strategy

If Heart Failure is Present (HFpEF with EF = 50%)

• Control systolic hypertension aggressively 5
• Avoid fluid overload 5
• Treat underlying causes (ischemia, valvular disease, hypertension) 3
• Consider guideline-directed medical therapy, though evidence is less robust than for HFrEF 6, 5

If Patient Has Improved from HFrEF to EF = 50%

Continue all HFrEF-directed therapies (ACE inhibitors/ARBs, beta-blockers, mineralocorticoid receptor antagonists, SGLT2 inhibitors) to prevent relapse 1

Specific Valvular Considerations

In severe aortic regurgitation with EF = 50%:

• This represents an indication for surgery if the patient is symptomatic or has LV end-diastolic diameter >70 mm or LV end-systolic diameter >50 mm (or >25 mm/m² BSA) 4

In severe aortic stenosis with EF = 50%:

• Preserved EF (≥50%) with severe AS and symptoms is a class I indication for aortic valve intervention 4

Common Pitfalls to Avoid

• Do not assume EF = 50% is "normal enough" to ignore: this value sits at the threshold and requires investigation 1, 2
• Do not rely on a single measurement: obtain serial assessments using the same equipment and methodology 2, 3
• Do not discontinue HFrEF therapy if the patient has improved to EF = 50% from a lower baseline 1
• Do not overlook diastolic dysfunction: assess left atrial size and diastolic parameters if heart failure symptoms are present, as diastolic dysfunction can coexist with preserved systolic function 2
• Do not assume higher EF always means better function: EF is load-dependent and cannot distinguish between preload, afterload, and intrinsic contractility 2

Follow-Up Protocol

• Serial echocardiography every 6-12 months if heart failure is present 4
• Repeat natriuretic peptides to track disease trajectory 1
• Monitor for symptom development or progression 3
• Reassess underlying etiology if EF declines below 50% 3