Left atrial structural and functional remodelling in Fabry disease and cardiac amyloidosis: A comparative analysis

Background: Fabry disease (FD) and transthyretin cardiac amyloidosis (TTR CA) are cardiomyopathies with hypertrophic phenotype that share several features, including left atrial (LA) enlargement and dysfunction, but direct comparative data are lacking. Aim of the present study was to perform a comparative analysis of LA remodelling between the two diseases. Methods and results: In this prospective study, a total of 114 patients (31 FD and 83 TTR CA) were included; all of them had left ventricular hypertrophy (LVH), defined as left ventricular (LV) wall thickness ≥ 12 mm. Despite similar degree of LVH, patients with TTR CA showed worse LV systolic and diastolic function. LA maximal volume index was not significantly different between the two groups (p = 0.084), while patients with TTR CA showed larger LA minimal volume index (p = 0.001). Moreover, all phases of LA mechanics were more impaired in the TTR CA group vs FD (reservoir: 6.9[4.2–15.5] vs 19.0[15.5–29.5], p < 0.001). After excluding patients with atrial fibrillation (AF), these differences remained clearly significant. In multivariable regression analyses, LA reservoir strain showed an independent correlation with TTR CA, controlling for demographic characteristics, AF and LV systolic and diastolic performance (p ≤ 0.001), whereas LV global longitudinal strain did not. Finally, among echocardiographic parameters, LA function demonstrated the highest accuracy in discriminating the two diseases. Conclusions: TTR CA is characterized by a more advanced LA structural and functional remodelling in comparison to patients with FD and similar degree of LVH. The association between TTR CA and LA dysfunction remains consistent after adjustment for potential confounders.