Visual estimation versus quantitative assessment of left ventricular ejection fraction: A comparison by cardiovascular magnetic resonance imaging

Purpose The aim of this study was to compare the visual and quantitative assessment for left ventricular ejection fraction (LVEF) in normal subjects and patients with impaired LV function. Methods One hundred subjects (40 normal subjects, 40 patients with ischemic cardiomyopathy, and 20 patients with nonischemic cardiomyopathy) were investigated using a 1.5-T cardiovascular magnetic resonance imager. Images were acquired by a fast gradient-echo sequence with steady-state free precession using the standard short-axis method. Left ventricular EF was calculated from the sums of the outlined areas using the Simpson rule. Interobserver variability between the calculated and the visual EF was assessed. Analyses were performed randomly and blinded by 2 independent observers. Results Left ventricular EF was significantly underestimated by the visual read in all 3 groups (mean difference: normal subjects -2.6%+/- 2.6%, ischemic cardiomyopathy -1.7%+/- 2.1%, and nonischemic cardiomyopathy -1.2%+/- 2.1%; P <=.02). The difference was larger in normal subjects than in patients with cardiomyopathy (P=.04). The interobserver variability was smaller for the quantitative assessment than for the visual estimation. Conclusion Left ventricular EF is underestimated by visual estimation compared with the quantitative assessment. The visual approach for EF assessment may be used for rapid assessment of left ventricular function in clinical practice where accuracy is of less concern. For most accurate analysis, the quantitative standard short axis approach is required.