Assessing left atrial dysfunction in cardiac amyloidosis using LA-LV strain slope.

Aims: Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative disease of the myocardium in which extracellular deposits of amyloid cause progressive cardiac impairment. 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 LV hypertrophy (LVH). We hypothesized that LA strain in ATTR-CM patients is abnormal and more independent of LV strain, compared to LVH patients.

Methods and results: Retrospective study based on echocardiographic data including 30 patients diagnosed with ATTR-CM based on an end-diastolic interventricular septal (IVSd) thickness of ≥14 mm, and 29 patients with LVH (IVSd ≥ 14 mm 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 used regression line to determine a LA-LV strain slope. 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 receiver operating characteristic (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).

Conclusion: 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 cardiac amyloidosis and potentially unmasks LA amyloid infiltration; this could potentially enable quicker diagnosis and initiation of treatment for ATTR-CM.