Systemic lupus erythematosus (SLE) is associated with an increased risk of cardiovascular disease. The purpose of the current study was to explore the amount of energy loss (EL) using vector flow mapping (VFM) in the detection of early stage left ventricular (LV) dysfunction among patients with SLE. Eighty-nine patients with SLE and fifty-six healthy controls were enrolled. SLE patients were further divided into inactive (SLEDAI ≤ 4, n = 43) and active (SLEDAI ≥ 5, n = 46) subgroups. A prosound F75 echocardiography machine was used for echocardiographic examination. Intra-cardiac flow images were analysed by a VFM workstation. Compared with the healthy group, the inactive SLE group had increased diastolic EL values (38.05 mW/m vs. 33.02 mW/m, p = 0.010). However, the systolic EL values were comparable between the inactive SLE group and the control group (26.07mW/m vs 23.15 mW/m, p = 0.105). The active SLE group exhibited significantly higher diastolic (104.13 mW/m vs 33.02 mW/m, p < 0.001) and systolic (48.83 mW/m vs 23.15 mW/m, p < 0.001) EL values than the control group. The most notable correlation was observed between the values of the diastolic EL and SLEDAI in the inactive SLE group (r = 0.633, p < 0.001) and in the active SLE group (r = 0.824, p < 0.001). LV-dissipative EL assessed by using VFM is useful and feasible for estimating lesions of LV systolic and diastolic function in active SLE patients with preserved left ventricular ejection fraction. Increased disease activity may lead to increased risk of LV dysfunction.