Objectives: The aim of this study was to explore the left ventricular (LV) deformation changes and the potential impact of/ndeformation on outcome in patients with proven light-chain (AL) amyloidosis and LV hypertrophy./nBackground: Cardiac involvement in AL amyloidosis patients is associated with poor outcome. Detecting regional cardiac/nfunction by advanced non-invasive techniques might be favorable for predicting outcome./nMethods: LV longitudinal, circumferential and radial peak systolic strains (Ssys) were assessed by speckle tracking imaging/n(STI) in 44 biopsy-proven systemic AL amyloidosis patients with LV hypertrophy (CA) and in 30 normal controls. Patients/nwere divided into compensated (n = 18) and decompensated (n = 26) group based on clinical assessment and followed-up/nfor a median period of 345 days./nResults: Ejection fraction (EF) was preserved while longitudinal Ssys (LSsys) was significantly reduced in both compensated/nand decompensated groups. Survival was significantly reduced in decompensated group (35% vs. compensated 78%,/nP = 0.001). LSsys were similar in apical segments and significantly reduced in basal segments between two patient groups./nLSsys at mid-segments were significantly reduced in all LV walls of decompensated group. Patients were further divided into/n4 subgroups according to the presence or absence of reduced LSsys in no (normal), only basal (mild), basal and mid/n(intermediate) and all segments of the septum (severe). This staging revealed continuously worse prognosis in proportion to/nincreasing number of segments with reduced LSsys (mortality: normal 14%, mild 27%, intermediate 67%, and severe 64%)./nMid-septum LSsys,11% suggested a 4.8-fold mortality risk than mid-septum LSsys$11%. Multivariate regression analysis/nshowed NYHA class and mid-septum LSsys were independent predictors for survival./nConclusions: Reduced deformation at mid-septum is associated with worse prognosis in systemic amyloidosis patients with/nLV hypertrophy.