BACKGROUND: Automated border detection(ABD) is a new echocardiographic modality providing continuous on-line measurements of left ventricular(LV) cavitary ares, volume, and ejection fraction(EF) throughout the cardiac cycle. Previous study showed that LV volume and EF measurements with ABD system approximate manually traced LV volume and EF obtained with conventional 2-dimensional echocardiography. But further clinical validation needs a comparison of LV function between the ABD system and established methods. The purpose of this study is to compare EF, peak ejection rate(PER) and peak filling rate(PFR) between on-line ABD system and the gated cardiac blood pool scinitigraphy. METHOD: 27 patients with an apical 4 chamber view of LV in which at least 75% of the endocardium was clearly seen were selected for this study. They had a normal sinus rhythm and underwent echocardiographic study on the same day of or one day before gated cardiac blood pool scintigraphic study. The off-line estimation of LV volume was performed by the method of disc, after manually tracing the endocardial border on the apical 4 chamber view and EFoff was calculated. Also on that view the ABD system was turned on, and EFABD, PEABD, PEABD were calculated automatically from LV volume curve. They were compared with EFRI, PERRI, and PERRI obtained by the gated cardiac blood pool scintigraphy. RESULTS: 1) EFoff and EFABD were highly correlated with EFRI(r=0.78, 0.90 respectively : p<0.001). The mean difference between EFRI and EFoff was 4+/-9%, and the limits of agreement between EFRI and EFoff were -16~22%, EFoff were less than EFRI(p<0.05). The mean difference between EFRI and EFABD was 5+/-7%, and the limits of agreement between EFRI and EFoff were -9~+19%. EFABD was also less than EFRI(p<0.05). 2) PERABD and PERABD were highly correlated with PERRI and PERRI(r=0.74, 0.60, respectively ; p<0.001). The mean difference between PERRI and PERABD was -0.1+/-0.7EDV(enddiastolic volume)/sec, and the limits of agreement were -1.5~+1.3EDV/sec. PEABD was slightly greater than PERRI(p>0.05). The mean difference between PERRI and PEABD was -0.8+/-0.8EDV/sec, and the limits of agreement were -2.4~+0.8EDV/sec. PEABD were greater than PERRI(p<0.01). CONCLUSION: EF, PER, PER measurements by the ABD system and the gated cardiac blood pool scintigraphy have significant correlations. Thus ABD echocardiography is a useful method for assessement of LV function.