The effect of community-acquired pneumonia on myocardial injury in systemic lupus erythematosus: Insights from cardiac magnetic resonance

Objectives Myocardial injury (MInj) in systemic lupus erythematosus (SLE) has been observed in several studies. However, clinical predictors of MInj remain unclear. We aim to explore the effects of community-acquired pneumonia (CAP) on MInj in SLE patients according to cardiac magnetic resonance (CMR) T1 mapping. Methods SLE patients with or without CAP and healthy controls underwent CMR screening. The CMR protocol included: cines, T1- and T2 mapping, and late gadolinium enhancement (LGE). Clinical characteristics, CMR findings, and T1 mapping measuremments were compared between subgroups. Clinical assessment was performed on the subjects. Results Thirty-eight SLE patients were screened, including 18 patients with CAP (CAP group) and 20 age- and gender-matched patients without CAP (non-CAP group) as well as 26 healthy controls. The platelet count of CAP group was higher than the non-CAP group (p = 0.015). Compared with the health control group, native T1 was higher in the CAP group (p < 0.001) and the non-CAP group (p = 0.002). ECV was higher in the CAP group (p < 0.001) and the non-CAP group (p = 0.002). The LV ejection fraction (p = 0.049) and RV ejection fraction (p = 0.026) of the CAP group was lower than that of the healthy control group, whereas no significant difference was observed between non-CAP and healthy control groups. Conclusions This is the first study that assesses the effects of CAP on MInj of SLE patients by CMRI T1 mapping. We highlight SLE patients with CAP who are at increased risk of MInj, manifesting as myocardial inflammation, diffuse myocardial fibrosis, and decreased ventricular function.