assessment of light-chain amyloidosis using 3D speckle tracking echocardiography: Differentiation from other forms of myocardial hypertrophy

Background. Cardiac amyloidosis (CA) is an infiltrative disease primarily caused by extracellular tissue deposition of amyloid fibrils in the myocardial interstitium. Over half of affected patients show cardiac involvement at diagnosis, and this condition is the most important prognostic factor in the natural progression of the disease. The aim of the present study was to examine left ventricular (LV) rotational mechanics in biopsy-proven CA by three-dimensional speckle-tracking echocardiography (3DSTE). Methods. Ten patients (67.9±10.3 years) with CA, 10 patients (68.6±11.7 years) with systemic arterial hypertension (HTN), 10 patients (59.9±13.8 years) with hypertrophic cardiomyopathy (HCM), and 10 age-matched normal controls were studied by conventional echocardiography and 3DSTE. LV longitudinal strain and systolic and diastolic strain rate were obtained in the basal, mid and apical segments of septal and lateral walls in apical 4-chamber view. Circumferential and radial strain and averaged LV rotation and rotational velocities from the base and apex were also determined. Results. LV longitudinal and circumferential strain were reduced in CA patients compared to controls (-14.6% vs -19.7%, p =.005, and -16.9% vs -27.1%, p =.013, respectively) with the most prominent impairment at the basal segments. Peak basal rotation (-5.1±1.4 vs -6.8±2.2degree, p =.001), peak apical rotation (8.7±3.1 vs 10.8±3.4degree, p <.05), and peak untwisting rate (64.3±11 vs 79.3±14degree/s, p =.02) were significantly lower compared to controls. Significant impairment of peak basal rotation was shown in CA patients compared to HTN (p<.05) and HCM patients (p<.01). Comparison of ROC curves for detecting CA showed that the AUC using basal rotation was significantly larger than the other echocardiographic parameters used for diagnosing CA (AUC 0.95, 95% CI 0.87-0.98). Conclusions. Different aspects of LV rotational mechanics are shown in CA, with significant basal hyporotation being the most frequent pattern. This pattern could identify early cardiac involvement and help to differentiate patients with CA from patients with other causes of increased LV wall thickness.