Two-dimensional global and segmental longitudinal strain: are the results from software in different high-end ultrasound systems comparable?

To compare the peak global longitudinal myocardial strain (PGLS) and peak segmental longitudinal myocardial strain (PSLS) values by speckle-tracking echocardiography (STE) obtained using two different echocardiography devices. STE is an emerging quantitative ultrasound technique that allows an accurate evaluation of global and segmental myocardial function. However, there is a lack of standardization of the acquired data among different manufacturers. Sixty-three subjects, mean age 56.2±10.4 years, underwent complete echocardiographic studies with two different devices (Philips IE33 and General Electric VIVID E9) performed by the same operator. Thirty-one of them had known cardiac disease, with estimated left ventricular ejection fraction <50%, while 32 were free of any cardiovascular disease (control subjects). All images were digitally stored and analyzed using off-line post processing with QLAB 9 and EchoPAC 11 Software packages. PSLS and PGLS were calculated. A strong relationship between QLAB and EchoPAC was found for PGLS (r=0.91, P<0.001), PSLS-4 chamber (CH; r=0.79, P<0.001), PSLS-2CH (r=0.73, P<0.001), and PSLS-3CH (r=0.78, P<0.001) QLAB. Bland-Altman analysis showed absolute differences vs average of -0.16, -0.37, -0.21, and -0.16 for PGLS, PSLS-4CH, PSLS-2CH, and PSLS-apical long-axis views respectively. Segmental analysis showed a good agreement between the apical segments, whereas poor correlations were found for the basal segments. Receiver operating characteristic curve analysis showed that cutoff values for PGLS of -17.5 and -17.75% with Philips or GE systems gave a sensitivity and specificity of 93.5 and 87.5%, and 90 and 87.5%, respectively, in the discrimination of the patients from the controls. Both Philips and GE echo stations were found to give comparable results for PGLS, with approximately the same cutoff values, suggesting that their PGLS results may be interchangeable.