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Left Ventricular Ejection FractionEdit

Left ventricular ejection fraction (LVEF) is a fundamental measure of how well the left ventricle—the heart’s main pumping chamber—expels blood with each beat. It is calculated as the fraction of blood ejected from the left ventricle during systole relative to its filling volume at end-diastole, expressed as a percentage. In clinical practice, LVEF is a central parameter for diagnosing, staging, and guiding treatment in a wide range of heart conditions.

Normal values for LVEF are typically in the range of about 55% to 70%. Values lower than the normal range indicate varying degrees of systolic dysfunction, with lower fractions associated with worse prognosis and higher risk of heart failure–related events. LVEF is most commonly estimated via imaging, especially two-dimensional echocardiography, but can be measured more precisely with three-dimensional echocardiography or cardiac magnetic resonance imaging (MRI). In practice, imaging-based estimates are subject to variability due to technical factors and loading conditions, so serial measurements and clinical context are essential.

Physiology and measurement

  • The left ventricle fills during diastole and ejects blood during systole. LVEF reflects the heart’s systolic performance but is influenced by preload (volume status) and afterload (vascular resistance).
  • Imaging methods:
    • Echocardiography is the workhorse method, using calculations such as the biplane Simpson’s rule to estimate volumes and derive LVEF.
    • Cardiac MRI is often considered the reference standard for measuring ventricular volumes and function, providing high accuracy and reproducibility.
    • CT and other modalities can also contribute when MRI is unavailable.
  • Categories of systolic function based on LVEF:
    • Heart failure with reduced ejection fraction (HFrEF): typically defined as LVEF ≤ 40%.
    • Heart failure with mid-range ejection fraction (HFmrEF): LVEF 41–49%.
    • Heart failure with preserved ejection fraction (HFpEF): LVEF ≥ 50%.
  • Practical considerations:
    • LVEF is a load-dependent parameter; rapid changes in blood pressure, volume status, or medications can shift the value.
    • Inter-observer and intra-observer variability can occur, underscoring the value of repeat studies and complementary imaging when needed.

Clinical significance and management implications

  • Prognosis: LVEF provides important prognostic information in a wide array of heart diseases, including ischemic heart disease, dilated cardiomyopathy, and valvular disorders. Lower LVEF generally signals higher risk for heart failure hospitalization, arrhythmias, and mortality.
  • Guiding therapy:
    • In HFrEF, several classes of medications have demonstrated survival and morbidity benefits, including angiotensin-converting enzyme inhibitors or ARBs, beta-blockers, and mineralocorticoid receptor antagonists. More recently, SGLT2 inhibitors have shown additional value across a broad spectrum of heart failure patients.
    • Device therapy decisions, such as implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT), often use LVEF as one of the key criteria to identify candidates (for example, LVEF ≤ 35% in certain patients with systolic dysfunction).
    • In HFpEF and HFmrEF, treatment focuses more on controlling comorbidities (hypertension, diabetes, obesity), relieving symptoms, and addressing volume status, since the evidence base for mortality reduction by drugs is more limited than in HFrEF.
  • Imaging-guided decisions: When LVEF falls into a threshold that prompts specific interventions, clinicians integrate the value with symptoms, comorbidities, rhythm status, and imaging findings to tailor therapy.

Controversies and debates

  • Thresholds and terminology: The use of discrete LVEF cutoffs to define heart failure phenotypes (HFrEF, HFmrEF, HFpEF) is clinically useful but imperfect. Patients near category boundaries may differ in prognosis and response to therapy, and some experts argue for individualizing thresholds rather than rigid ranges.
  • LVEF as a sole endpoint: Critics have noted that LVEF, while informative, is not the sole determinant of patient outcomes. Clinical status, quality of life, and other measures (e.g., biomarkers, functional capacity) are essential in management decisions. Advocates argue that LVEF remains a powerful, objective tool for risk stratification and selecting evidence-based therapies.
  • Access and cost considerations: Therapies that improve outcomes in HFrEF—such as ACE inhibitors, beta-blockers, MRAs, SGLT2 inhibitors, and certain devices—can be expensive or require careful monitoring. A policy emphasis on broad access to guideline-directed medical therapy is debated in systems that balance cost with population health gains. Proponents of limited expansion argue for prioritizing high-value care, while critics warn against delaying treatment for patients who could benefit.
  • Woke criticisms of guidelines: Some observers claim that clinical guidelines are influenced by political or cultural agendas in addition to science. Proponents of the guidelines respond that recommendations are grounded in large, randomized trials and decades of clinical experience; while industry funding and conflicts of interest warrant transparency, the convergent evidence across diverse populations reduces the likelihood that policy would be driven by nonclinical concerns alone. Critics of this line argue that overly broad guidelines can stifle individualized care; supporters counter that standardized, evidence-based practices improve overall outcomes and resource use when applied judiciously. In any case, the core purpose of LVEF–related guidelines is to better identify patients who will benefit from proven therapies and monitoring strategies.
  • Population diversity and observational limits: Research shows that outcomes with LVEF-based therapies can vary by age, comorbidity burden, and other factors. This has led to calls for more personalized approaches that go beyond a single measurement, while still recognizing the value of LVEF as a cornerstone of assessment.

See also