Heterogeneous myocardial contraction detected by speckle tracking echocardiography in systemic lupus erythematosus is associated with complement protein C4: a cross-sectional study from a Swedish tertiary referral centre.

Although systemic lupus erythematosus (SLE) is associated with an increased risk of cardiovascular disease, conventional echocardiographic measures often fail to detect early myocardial dysfunction. This study assesses left ventricular mechanical dispersion (LVMD) and its associations with vascular pathology in patients with SLE, with the focus on complement proteins. A cross-sectional study was conducted on 55 patients with SLE, categorised into sub-groups with skin and joint involvement, lupus nephritis (LN), and antiphospholipid syndrome (APS), along with 31 age- and sex-matched healthy controls. Speckle tracking echocardiography was used to assess myocardial function, including global longitudinal strain (GLS) and LVMD. The vascular pathology of each subject was evaluated using carotid and central arteries ultrasound to assess the intima-media thickness (IMT) and atherosclerotic plaque burden. LVMD was significantly increased in patients with SLE compared with the controls (p < 0.001), with APS patients displaying the highest values (median, 51 ms vs. 36 ms in controls). GLS did not differ between the groups. APS and LN patients exhibited mild right ventricular impairment. Higher LVMD values correlated with increased IMT in the internal carotid artery (p = 0.04) and aortic arch (p < 0.001), as well as with increased atherosclerotic plaque burden (p = 0.04). In multivariable regression analysis, complement protein C4 was an independent predictor of LVMD, suggesting a link between overall systemic inflammation and myocardial dysfunction in SLE. Our findings highlight the importance of speckle tracking echocardiography in uncovering sub-clinical cardiac dysfunction in SLE and call for additional research on complement-directed therapies to prevent atherosclerotic inflammation.