Left Ventricular Apical Long-Axis Length and Ejection Fraction: A Proof-of-Concept Analysis

BACKGROUND: Accurate estimation of left ventricular ejection fraction (LVEF) is vital in cardiology practice for diagnostic, prognostic, and management decisions. The biplane Simpson method is the standard but can be subject to limitations, particularly in cases of poor image quality or when subjective interpretation is involved. This study aims to evaluate whether LVEF can be reliably estimated using simpler apical four-chamber views without the need for complex calculations. METHODS: A retrospective review of 260 echocardiographic studies from the University of Arkansas for Medical Sciences database was conducted. LVEF was calculated using the Simpson's biplane method and compared with longitudinal apical LV length measurements in systole and diastole. Statistical analyses, including regression and receiver operating characteristic (ROC) curves, were used to determine the relationship between LVEF and apical LV lengths. RESULTS: Patients were divided into two groups based on LVEF values (>50% normal, <50% reduced). Longitudinal apical LV length measurements demonstrated significant differences between the groups. Delta changes in LV length (>14 cm) showed high sensitivity (94.2%) and specificity (95.7%) in identifying normal LVEF. ROC analysis revealed that end-systolic lengths ≤7.3 cm could predict normal LVEF with good accuracy. CONCLUSIONS: Simple measurements of longitudinal apical LV length changes between systole and diastole can serve as a reliable surrogate for LVEF, offering a rapid bedside alternative to the biplane Simpson method. These findings highlight the potential for streamlining LVEF estimation, particularly in settings where time and resources are limited.