This record contains raw data related to the article "Structural and functional abnormalities of left-sided cardiac chambers in Barlow’s disease without significant mitral regurgitation". Aims This study aims to explore the presence of left ventricular (LV) and left atrial (LA) morphological and functional abnormalities in patients with Barlow’s disease (BD) without significant mitral regurgitation (MR) and to investigate whether these abnormalities may predict MR progression. Methods and results Consecutive patients with BD were retrospectively identified from two tertiary centres; those with MR graded from trivial to mild-to-moderate were selected and matched with healthy controls in a 1:1 ratio. Conventional and speckle-tracking echocardiographic data were collected. The development of moderate-to-severe or greater MR was evaluated on follow-up echocardiograms. Patients with BD (n = 231) showed increased LV dimensions and indexed LV mass (LVMi) in comparison with controls (P < 0.001); LV remodelling worsened with higher MR severity and was accompanied by an increased prevalence of eccentric LV hypertrophy (eLVH). Moreover, BD patients had larger LA volumes and more impaired LA reservoir strain vs. controls (P < 0.001), while LV strain was similar between the two groups. Multivariable linear regression analyses in the overall population identified BD and MR grade as independent predictors of remodelling markers (LV dimensions, LVMi, and LA volume) and BD as independent correlate of LA strain. MR progression was observed in 51 BD subjects (out of 170 patients with available follow-up). On Cox regression analysis, age, eLVH, mild-to-moderate MR, and mitral annular disjunction (MAD) emerged as independent predictors of MR progression. Conclusion BD patients without significant MR show early LV and LA remodelling, together with reduced LA strain. MR progression was associated with eccentric LV remodelling, MAD, and MR severity.