Left Atrial Deformation in Paediatric Dilated and Hypertrophic Cardiomyopathy: Insights from Two-Dimensional Speckle-Tracking Echocardiography

<b>Background</b>: Left atrial strain (LAS) derived from speckle-tracking echocardiography (STE) provides a sensitive, load-dependent measure of atrial function and ventricular filling pressures. Data on LAS in paediatric cardiomyopathies are still scarce; therefore, this study aimed to assess LA phasic function in dilated (DCM) and hypertrophic (HCM) cardiomyopathy and to determine its relationship with clinical and echocardiographic indices of disease severity. <b>Methods</b>: We conducted a cross-sectional case-control study that included 84 children (DCM n = 29, HCM n = 29, control n = 26) who underwent comprehensive clinical and echocardiography evaluation, including LAS parameters (reservoir-LASr; conduit-LAScd; and contractile-LASct). Group comparisons were performed using ANOVA or Kruskal-Wallis tests with post hoc adjustments, and correlations were analysed using Pearson's or Spearman's coefficients. Multivariable linear and logistic regression models were adjusted for age, body surface area (BSA), heart rate (HR), and blood pressure (BP) percentiles. <b>Results</b>: LASr and LAScd were significantly reduced in both cardiomyopathy groups compared with controls (<i>p</i> < 0.001), following a graded pattern (DCM < HCM < control). In DCM, lower LASr was independently associated with higher left atrial volume index (LAVi) and elevated E/E' ratio, whereas in HCM, septal hypertrophy (IVSd Z-score) and log NT-proBNP were dominant determinants of impaired LASr. In logistic regression, LASr (OR = 0.93, <i>p</i> = 0.016) and LAScd (OR = 1.21, <i>p</i> = 0.001) independently predicted severe NYHA/Ross functional class after covariate adjustment, while LASct showed no significant association. <b>Conclusions</b>: These findings demonstrate that LA reservoir and conduit strain are markedly impaired in paediatric cardiomyopathy and are strongly linked to structural remodelling and functional limitation, underscoring their value as sensitive non-invasive markers of disease severity.