A comparative evaluation of transesophageal and transthoracic echocardiography for measurement of left ventricular systolic strain using speckle tracking

Objective: The authors hypothesized that the measurement of strain by speckle tracking with transesophageal echocardiography (TEE) is feasible and comparable to transthoracic echocardiography (TTE). Design: A prospective observational comparative study. Setting: A university hospital. Participants: Adult patients undergoing elective cardiac surgery. Interventions: Structured intraoperative TTE and TEE examination. Measurements and Main Results: Images were obtained after the induction of anesthesia from 25 patients to enable speckle tracking of the left ventricle in comparable short- and long-axis (SAX and LAX) views using TTE and TEE. Left ventricular strain was measured offline using both modalities and correlation assessed using the Pearson test with assessment of bias using the Bland-Altman method. Significantly more segments were tracked by TEE than TTE in LAX views but not SAX views. Correlation was moderate between TTE and TEE (r = 0.5-0.6) for longitudinal strain in the LAX views, whereas it was poor for regional radial strain (r = 0.07). Correlation for global circumferential strain was higher for the apical SAX views (r = 0.7) than the basal or mid- SAX views. Speckle tracking by TEE showed excellent reproducibility with small bias. Conclusions: Strain measured by speckle tracking in TEE correlated moderately with TTE for global strain and poorly for regional strain. This may be explained by differences in scanning frequency and other imaging factors. Nevertheless, because of the high degree of reproducibility, it may be a useful tool to quantify intraoperative changes in ventricular function with TEE. However, equivalence between TTE and TEE cannot be assumed, and limits of comparability should be recognized.