Comparative validity of left ventricular ejection fraction measured by M-mode versus three-dimensional echocardiography: A prospective observational study

Background: Accurate assessment of left ventricular ejection fraction (LVEF) is essential for the diagnosis, risk stratification, and management of cardiovascular disease. Although M-mode echocardiography remains widely used due to its simplicity and accessibility, it relies on geometric assumptions and one-dimensional measurements. Three-dimensional (3D) echocardiography enables direct volumetric assessment without geometric assumptions and is recommended by contemporary imaging guidelines. This study aimed to evaluate the validity and agreement of M-mode–derived LVEF compared with 3D echocardiographic LVEF.

Methods: In this prospective observational study, 200 consecutive adult patients undergoing transthoracic echocardiography were enrolled. LVEF was measured using M-mode (Teichholz method) and 3D echocardiography. Correlation between methods was assessed using Pearson correlation coefficient. Agreement was evaluated using Bland–Altman analysis. Diagnostic performance of M-mode LVEF for identifying reduced systolic function (LVEF <50%) was assessed using receiver operating characteristic (ROC) analysis.

Results: A total of 200 patients were included, of whom 198 had complete paired measurements (mean age 57.1 ± 10.9 years; 69.7% male). Mean LVEF measured by M-mode was 51.1 ± 11.8%, whereas mean LVEF measured by 3D echocardiography was 54.5 ± 10.9%. M-mode–derived LVEF demonstrated a strong positive correlation with 3D LVEF (r = 0.911, p < 0.001). However, Bland–Altman analysis revealed a mean bias of −3.37% with wide limits of agreement (−12.95% to +6.20%), indicating poor agreement between methods. M-mode LVEF demonstrated excellent diagnostic performance for identifying reduced systolic function, with an area under the curve of 0.973. An optimal cutoff of 48% yielded a sensitivity of 98.4% and specificity of 82.5%.

Conclusions: Although M-mode–derived LVEF demonstrates strong correlation with 3D echocardiography, it shows significant bias and wide limits of agreement, limiting its clinical interchangeability. Three-dimensional echocardiography provides a more accurate and reliable assessment of left ventricular systolic function and should be preferred in contemporary clinical practice.