Contrast-Enhanced Echocardiographic Measurement of Left Ventricular Wall Thickness in Hypertrophic Cardiomyopathy: Comparison with Standard Echocardiography and Cardiac Magnetic Resonance

Abstract

Background: Left ventricular wall thickness (LVWT) measurement is key in the diagnostic and prognostic assessment of hypertrophic cardiomyopathy (HCM). Recent investigations have highlighted discrepancies in LVWT by cardiac magnetic resonance (CMR) and standard echocardiography (S-Echo) in this condition. The aim of this study was to elucidate the role of contrast-enhanced echocardiography (C-Echo) to optimize LVWT measurement in patients with HCM.

Methods: Fifty patients with HCM were prospectively enrolled, undergoing S-Echo, C-Echo, and CMR. Blinded LVWT measurements were performed according to a 16-segment left ventricular model using all three imaging techniques. Agreement between both echocardiographic modalities and CMR (as the reference technique) at the segmental level was tested using Bland-Altman analyses. Reproducibility on segmental measurements by S-Echo and C-Echo was also investigated.

Results: Patients' mean age was 47 ± 21 years, and 35 (70%) were men. Maximal mean LVWT by S-Echo (20.1 ± 3.8 mm) was greater than the values derived using C-Echo (17.6 ± 4.0 mm, P < .01) and CMR (17.7 ± 4.5 mm, P < .01), with no statistically significant difference between the latter two. Segmental Bland-Altman models demonstrated globally smaller bias and narrower 95% limits of agreement for C-Echo compared with S-Echo. Across all left ventricular segments, LVWT by C-Echo was 2.4 mm lower (range, 1.0-2.5 mm) than that derived by S-Echo, which accounted for a 25% intertechnique difference. Regarding maximal LVWT, the mean absolute difference between C-Echo and S-Echo was 3.0 ± 1.9 mm (range, 0.0-7.9 mm), which represented a 15% intertechnique change. Data analyses demonstrated globally less intra- and interobserver variability in segmental LVWT derived from C-Echo compared with S-Echo.

Conclusions: C-Echo rendered LVWT measurements closer to those derived by the reference technique (CMR) and improved reproducibility compared with S-Echo. C-Echo represents a suitable tool for LVWT measurement in patients with HCM as an alternative to CMR whenever this is not available or possible.

Keywords: Cardiac magnetic resonance; Contrast echocardiography; Hypertrophic cardiomyopathy; Left ventricular wall thickness; Transthoracic echocardiography.