Speckle-tracking strain of the left atrium: a transoesophageal echocardiographic validation study
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AIMS: The aims of this study were (1) to evaluate the relationship between novel two-dimensional transthoracic indices of left atrial (LA) mechanical function (speckle-tracking- and tissue Doppler-derived parameters), conventional indices (A-wave peak velocity and velocity-time integral, and A' velocity), and transoesophageal echocardiographic parameters (LA appendage emptying velocity and spontaneous echocardiographic contrast); and (2) to assess to clinical feasibility of these novel transthoracic echocardiographic indices. METHODS AND RESULTS: Transthoracic echocardiography was performed immediately prior to or following clinically indicated transoesophageal echocardiography in 100 individuals. Longitudinal reservoir LA strain, and reservoir, conduit, and atrial contractile strain rate were measured by both speckle-tracking and tissue Doppler approaches. Inter- and intra-observer variability in 20 randomly selected cases was evaluated by the Bland-Altman technique. The time required per analysis for these novel transthoracic echocardiographic indices was recorded. In relation to LA appendage emptying velocity, the respective absolute r-values for speckle-tracking reservoir strain, and reservoir, conduit, and atrial contractile strain rate were 0.53 (P < 0.001), 0.40 (P < 0.001), 0.21 (P = 0.05), and 0.61 (P < 0.001). The absolute r-values for tissue Doppler reservoir strain, and reservoir, conduit, and atrial contractile strain rate were 0.57 (P < 0.005), 0.53 (P < 0.001), 0.022 (P = 0.8), and 0.46 (P < 0.001), respectively. In contrast, the r-values for A-wave peak velocity and velocity-time integral, and A' velocity were 0.20 (P = 0.01), 0.26 (P = 0.05), and 0.35 (P = 0.007), respectively. Speckle-tracking-derived parameters achieved the greatest area-under-the-receiver-operating characteristic curve in the identification of moderate-severe LA spontaneous echocardigraphic contrast and were more rapidly measured (P < 0.001), while exhibiting similar reproducibility to tissue Doppler-derived measures. CONCLUSION: Assessment of LA mechanical function using speckle-tracking echocardiography is a valid approach compared with transoesophageal echocardiography, and is clinically feasible.
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