Comparison of Tissue Doppler Velocities Obtained by Different Types of Echocardiography Systems: Are They Compatible?

Background: Both systolic and diastolic tissue Doppler (TD) velocities have an important diagnostic and prognostic role in cardiology. We aimed to compare TD velocities between two different echocardiography systems. Patients: Thirty-one consecutive patients (mean age: 65.2 +/- 17.5 years; 12 males) were enrolled. Methods: Systolic (Sa), early (Ea), and late (Aa) diastolic velocities were measured by TD at the lateral mitral annulus by a Sonos 2000 (Hewlett-Packard, Andover, MA, USA) and a Philips iE33 system. The E/Ea ratio was calculated. Results: Ea, Aa, and Sa velocities were higher when measured by the Sonos system (Ea: 13.2 +/- 4.1 cm/s vs. 8.3 +/- 3.6 cm/s; Aa: 14.8 +/- 3.8 cm/s vs. 9.3 +/- 2.3 cm/s; Sa: 15.2 +/- 3.6 cm/s vs. 8.4 +/- 2.0 cm/s; P < 0.0001 all). A significant correlation was found in Ea and in Ea/Aa (r = 0.84 and r = 0.85 resp; P < 0.0001 for both), and a weaker in Aa (r = 0.43; P = 0.02) between the machines. The Bland-Altman analysis showed broad limits of agreement between the measurements for Ea, Aa, and Sa (mean difference: 4.95 cm/s; 5.52 cm/s; 6.73 cm/s, respectively; limits: 0.64-9.25 cm/s; -1.39-12.39 cm/s; -0.37-13.83 cm/s, respectively). An E/Ea ratio > 5.6 by the Sonos system showed 75% sensitivity and 79% specificity for elevated left ventricular filling pressure, defined as E/Ea > 10 by the reference Philips system. Conclusions: Although diastolic TD velocities had excellent correlations between the two machines, there was a systematic overestimation by the Sonos system. Since the limits of agreement do not allow replacing the measurements, we suggest using the same echocardiographic equipment at patient follow-up. (Echocardiography 2010;27:230-235).