Definition of Severely Reduced Left Ventricular Ejection Fraction
A left ventricular ejection fraction (LVEF) below 30% is considered severely reduced according to current clinical guidelines.
Classification of Left Ventricular Ejection Fraction
The European Society of Cardiology (ESC) classifies heart failure based on LVEF as follows:
- HFrEF (Heart Failure with reduced Ejection Fraction): LVEF < 40%
- HFmrEF (Heart Failure with mildly reduced Ejection Fraction): LVEF 40-49%
- HFpEF (Heart Failure with preserved Ejection Fraction): LVEF ≥ 50%
Within the HFrEF category, LVEF < 30% is specifically recognized as severely reduced ejection fraction 1.
Clinical Significance of Severely Reduced LVEF
Severely reduced LVEF (< 30%) has important clinical implications:
Mortality risk: Patients with LVEF < 30% have significantly higher mortality rates compared to those with higher ejection fractions
Treatment decisions: Several therapeutic interventions are specifically indicated for patients with LVEF < 30%:
- Combined surgery for secondary mitral regurgitation and coronary artery bypass grafting should be considered in symptomatic patients with LVEF < 30% requiring coronary revascularization 1
- Isolated surgery for non-ischemic regurgitant mitral valve in patients with severe functional mitral regurgitation and LVEF < 30% may be considered in selected patients 1
Mode of death: When LVEF is severely depressed (< 15-20%), the prevailing mode of cardiac death is often non-sudden, or when sudden, it is frequently related to bradyarrhythmias or electromechanical dissociation rather than ventricular tachyarrhythmias 1
Prognostic Implications
The relationship between LVEF and prognosis is not always linear:
- Once LVEF falls below 20%, it may no longer be a strong predictor of mortality, as other factors such as peak VO₂ become more important prognostic indicators 2
- LVEF has a strong dose-dependent relationship with right ventricular ejection fraction (RVEF), with LVEF < 17% associated with significantly higher odds of abnormally low RVEF (< 20%) 3
Clinical Considerations
When managing patients with severely reduced LVEF:
- Early intervention: Consider that LVEF deterioration often begins before conditions like aortic stenosis become severe, and accelerates after valve area reaches critical thresholds 4
- Monitoring: Patients with LVEF ≤ 55% and ischemic etiology are at higher risk of transitioning from preserved to reduced ejection fraction over time 5
- Treatment optimization: Evidence-based medical therapy including ACE inhibitors like lisinopril has been shown to improve outcomes in patients with reduced LVEF 6
Key Takeaway
While various thresholds exist in different contexts, an LVEF < 30% is consistently recognized as severely reduced across major cardiovascular guidelines and has significant implications for treatment decisions and prognosis.