Objective:To evaluate the global and segmental myocardial work in patients with cardiac amyloidosis (CA) by left ventricular pressure-strain loop (PSL) noninvasively.Methods:Eighteen patients with CA in Beijing Chao-Yang Hospital from March 2018 to December 2020 were included as CA group, 20 healthy subjects were selected as control group. The global longitudinal strain (GLS) and mechanical dispersion (MD) of left ventricle were analyzed by two-dimensional speckle tracking imaging. The left ventricular PSL was used to assess global work index (GWI), global constructive work (GCW), global waste work (GWW), and global work efficiency (GWE). The mean value of left ventricular basal, mid and apical myocardial work index (MWI), constructive work (CW), waste work (WW) and work efficiency (WE) were calculated and compared between the two groups.Results:①Compared with the control group, GLS was decreased and MD was increased in CA group (all P<0.05). ②GWI, GCW, GWW and GWE were decreased in CA group compared with the control group (all P<0.05). ③In CA group, the MWI, CW and WE of the basal, mid and apical segments were lower than those of control group (all P<0.05), WW of the basal and mid segments were lower than those of apical segment(all P<0.05). The impairment of MWI, WW and WE in basal and mid segment were more significant than those of apical segment (all P<0.05). ④GWI, GCW and GWE were positively correlated with GLS ( r=0.854, 0.816, 0.748; all P<0.001) and LVEF ( r=0.674, 0.634, 0.650; all P<0.01), and negatively correlated with MD ( r=-0.657, -0.672, -0.710, all P<0.01). GWI and GCW were negatively correlated with E/e′ ( r=-0.493, -0.539; all P<0.05). Conclusions:The global, basal, mid and apical left ventricular myocardial work indices are decreased in CA patients. MWI, CW and WE show an apical sparing pattern. Quantitative assessment of myocardial work by PSL may provide more valuable information for CA patients.