Echocardiography is the imaging modality most frequently used to assess left ventricular ejection fraction(EF). However, the accuracy of the EF can be limited by the technical quality of the examination and observer variability. Recently, tissue Doppler was applied to acquire signals of myocardial systolic function, including systolic ejection velocity(Sa) and the systolic isovolumic acceleration rate(IVA). In that regard, IVA was reported in animal studies to be the ideal noninvasive index, because it was not affected by preload and afterload and provided a reliable assessment of contractility when examined against invasive gold standards. However, a paucity of data is available about its clinical application. We undertook this investigation to examine Sa and IVA in 40 normal subjects and 52 patients with depressed EF referred for echocardiographic examination, aiming to identify the signal with the highest reproducibility and the most accurate detection of depressed EF. Sa had the least inter- and intraobserver variabilities(3± 1.5% and 2.5± 1% , respectively), and IVA had the highest variability(8.1± 2.1% and 6.8± 2% , respectively). Although Sa and IVA were significantly lower in patients with depressed EF(p< 0.05), Sa had the best correlation with EF(r=0.65, p< 0.03) and Sa of< 7 cm/s was the most accurate(p< 0.05 vs IVA) in identifying patients with EF< 45% (sensitivity 93% , specificity 87% ). In conclusion, Sa velocity is the most suitable signal for clinical application as a surrogate for left ventricular EF, given its accuracy and reproducibility. Echocardiography is the imaging modality most frequently used to assess left ventricular ejection fraction (EF). However, the accuracy of the EF can be limited by the technical quality of the examination and observer variability. Recently, tissue Doppler was applied to acquire signals of myocardial systolic function, including systolic ejection velocity (Sa) and the systolic isovolumic acceleration rate (IVA). In that regard, IVA was reported in animal studies to be the ideal noninvasive index, because it was not affected by preload and after load and provided a reliable Assessment of contractility when examined against invasive gold standards. However, a paucity of data is available about its clinical application. We undertook this investigation to examine Sa and IVA in 40 normal subjects and 52 patients with depressed EF referred for echocardiographic examination, aiming to identify the signal with the highest reproducibility and the most accurate detection of depressed EF. Sa had the le (3 ± 1.5% and 2.5 ± 1% respectively), and IVA had the highest variability (8.1 ± 2.1% and 6.8 ± 2%, respectively). Although Sa and IVA were significantly lower in patients with Sa had the best correlation with EF (r = 0.65, p <0.03) and Sa of <7 cm / s was the most accurate (p <0.05 vs IVA) in identifying patients with EF <45 % (sensitivity 93%, specificity 87%). In conclusion, Sa velocity is the most suitable signal for clinical application as a surrogate for left ventricular EF, given its accuracy and reproducibility.