Observer Variation in the Echocardiographic Measurement of Maximum Atrial Septal Excursion: A Comparison of M-Mode with Two-Dimensional or Transesophageal Echocardiography

Background: Atrial septal aneurysm is typically diagnosed by transthoracic two-dimensional or transesophageal echocardiography (2DE or TEE). Such techniques are highly dependent on visual inspection which predisposes to observer variation. This study compares inter-and intraobserver variations in the measurement of maximum atrial septal excursion (MASE) obtained using transthoracic M-mode echocardiography (MME) with that obtained using 2DE or TEE. Methods: Consecutive patients with highly mobile atrial septal motion by visual inspection during 2DE or TEE were studied. MASE was estimated visually on 2DE or TEE. MME tracings were obtained with the cursor bisecting the parabola formed by the atrial septum at its maximum deviation from the midline. Electronic calipers were used to measure MASE for all echocardiographic techniques. Two observers provided two measurements each. Observer variation was determined by assessing standard deviation and confidence intervals of inter-and intraobserver differences. Results: Interobserver analysis showed standard deviations of 0.077 cm (95% CI 0.065-0.094) for MME and 0.280 cm (95% CI 0.242-0.334) for 2DE or TEE. Intraobserver analysis showed standard deviations of 0.08 cm (95% CI 0.068-0.101) for MME and 0.318 cm (95% CI 0.274-0.381) for 2DE or TEE. The mean magnitude of measured MASE was 0.44 cm higher with MME than with 2DE or TEE (95% CI 0.068-0.101). Conclusions: MME assessment of MASE is associated with substantially lower inter-and intraobserver variation than 2DE or TEE assessment. The magnitude of MASE is substantially higher with MME than with 2DE or TEE. (ECHOCARDIOGRAPHY, Volume 26, November 2009)