Normal Shortening Fraction
A normal left ventricular shortening fraction (SF) is ≥30%, with values below this threshold indicating varying degrees of cardiac dysfunction. 1
Defining Normal Values
The most clinically relevant threshold comes from the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), which establishes:
- Normal cardiac function: SF ≥30% 1
- Mild dysfunction (Grade 1): SF 24-29% 1
- Moderate to severe dysfunction (Grade 2): SF 15-23% 1
- Symptomatic heart failure (Grade 3): SF <15% 1
Standard Reference Range
The American Society of Echocardiography provides normative data showing:
- Normal range for adults: 28-46% across all ages and both genders 1
- This represents the mean ± 2 standard deviations from healthy populations 1
Clinical Context and Interpretation
The 30% threshold serves as the critical clinical decision point. Values at or above this level indicate preserved systolic function when assessed over ≥5 years of follow-up in longitudinal studies. 1
Important Caveats:
Shortening fraction <25% identifies high-risk patients even when other measures appear normal, particularly in hypertensive patients or those with left ventricular hypertrophy 1
In pediatric populations with cardiomyopathy, SF ≤20% warrants consideration for anticoagulation therapy, while SF ≤10% represents severe dysfunction requiring more aggressive intervention 1
Measurement technique matters: The recommended method is 2D-guided M-mode or direct 2D linear measurements at the mid-ventricular level, perpendicular to the long axis 1
Limitations to Recognize:
Shortening fraction has significant limitations in patients with:
- Regional wall motion abnormalities from coronary disease 1
- Conduction abnormalities affecting synchrony 1
- Significant valvular regurgitation (may falsely elevate SF) 1
In these scenarios, volumetric methods (ejection fraction by Simpson's biplane method) provide more accurate global function assessment. 1