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Background: Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative disease of the myocardium in which extracellular deposits of amyloid cause progressive cardiac impairment.

Objectives: We aimed to evaluate left atrial (LA) deformation and its association with left ventricular (LV) deformation using LA-LV strain loops in patients with ATTR-CM and patients with left ventricular hypertrophy (LVH). We hypothesized that LA strain in ATTR-CM patients is abnormal and more independent of LV strain, compared to LVH patients.

Methods: Retrospective study based on echocardiographic data including 30 patients diagnosed with ATTR-CM based on an end diastolic interventricular septal (IVSd) thickness of ≥14mm, and 29 patients with LVH (IVSd ≥14mm and no ATTR-CM diagnosis) together with 30 controls. LV global longitudinal strain (LV-GLS) and LA strain, assessed as peak atrial longitudinal strain (PALS), were acquired and plotted to construct LA-LV strain loops and using regression line to determine a LA-LV strain slope.

Results: Significantly lower PALS and LA-LV strain slope values were detected in ATTR-CM patients compared to LVH patients (p=0.004 and p=0.014 respectively). A ROC curve demonstrated similar area under the curve (AUC) using PALS (AUC 0.72) and LA-LV slope (AUC 0.71), with both resulting in higher values than recorded for LV-GLS (AUC 0.62).

Conclusions: LA deformation demonstrates an independent ability to differentiate ATTR-CM from LVH. Combining LV strain and LA deformation analysis displays the mechanical LA/LV dissociation in ATTR-CA and potentially unmasks LA amyloid infiltration, this could potentially enable quicker diagnosis and initiation of treatment for ATTR-CM.