Choosing Apical Long-axis Instead of Two-chamber View Gives More Accurate Biplane Echocardiographic Measurements of Left Ventricular Ejection Fraction: A Comparison with Magnetic Resonance Imaging

Background We sought to evaluate whether the use of apical long-axis (APLAX) rather than two-chamber (2CH) view, in combination with four-chamber (4CH) view, improved accuracy of biplane echocardiographic measurements of left ventricular (LV) ejection fraction (EF), using magnetic resonance imaging (MRI) as a reference standard. Methods One hundred consecutive cardiac patients underwent cardiac MRI and 2D-echocardiography. Standard apical LV views were digitally acquired with baseline tissue harmonic imaging and low-power contrast echocardiography. Echo and MRI LV volumes were calculated by manual tracing and disc summation methods. Results Feasiblity for biplane volume measurements increased with the use of APLAX. Precontrast limits of agreement (LOA) for EF compared to MRI were −19.1 to 9.0 % (EF units) using 2CH, narrowing to −14.6 to 6.7% using the APLAX. With contrast, corresponding LOAs narrowed from −10.5 to 6.1%, to −7.3 to 3.8%, respectively. The improved accuracy with APLAX was evident regardless of image quality, previous MI and regional LV dyssynergy. Both intra- and interobserver variability improved by substituting 2CH with APLAX view. Conclusion Using APLAX rather than 2CH in combination with 4CH view improved feasibility, accuracy and reproducibility of biplane echocardiographic EF measurements in cardiac patients, even with optimisation of endocardial borders by contrast.