Objective: Visual estimation of left ventricular ejection fraction (LVEF) is still used in routine clinical practice. However, most of the studies evaluating the agreement between the visually estimated LVEF (ve-LVEF) and quantitatively measured LVEF (qm-LVEF) either have not used appropriate statistical methods or gold standard imaging modality. In this study, we aimed to assess the agreement between the ve-LVEF and qm-LVEF using contemporary statistical methods and cardiac magnetic resonance imaging (CMRI).
Methods: In 54 subjects who underwent 1.5-T CMRI, echocardiographic images were recorded after the CMRI procedure on the same day. Two independent observers estimated ve-LVEFs on echocardiographic records in a random and blinded fashion, and qm-LVEF was obtained by CMRI. Agreement between the ve-LVEF and qm-LVEF values and intra/interobserver ve-LVEF estimations were assessed using intraclass correlation coefficient (ICC), Bland-Altman analysis, and kappa statistics.
Results: There was a high agreement between the ve-LVEF and qm-LVEF (ICC 0.93, 95% confidence interval 0.88-0.96). Bland-Altman analysis also demonstrated a good agreement between ve-LVEF and qm-LVEF with ve-LVEF, on average, being 0.6% lower than that obtained by CMRI (mean -0.6, limits of agreement -10.5 and +9.3). A good agreement was also observed for LVEF categories ≤35%, 36%-54%, and ≥55% (unweighted kappa 0.71, linearly weighted kappa 0.76); and LVEF of <55% and ≥55% (kappa 0.80). Intra/inter observer agreement was good for ve-LVEFs (ICC value 0.96 and 0.91, respectively).
Conclusion: Visual approach for LVEF assessment may be used for rapid assessment of left ventricular systolic function in clinical practice, particularly in patients with good image quality.