Background: Myocarditis is an uncommon but serious manifestation of systemic lupus erythematosus (SLE). This study aimed to investigate clinical characteristics and outcomes of lupus myocarditis (LM) and to determine risk factors of LM in hospitalized Chinese patients with SLE.
Methods: We conducted a retrospective case-control study. A total of 25 patients with LM from 2001 to 2012 were enrolled as the study group, and 100 patients with SLE but without LM were randomly pooled as the control group. Univariable analysis was performed using Chi-square tests for categorical variables, and the Student's t-test or Mann-Whitney U-test was performed for continuous variables according to the normality.
Results: LM presented as the initial manifestation of SLE in 7 patients (28%) and occurred mostly at earlier stages compared to the controls (20.88 ± 35.73 vs. 44.08 ± 61.56 months, P = 0.008). Twenty-one patients (84%) experienced episodes of symptomatic heart failure. Echocardiography showed that 23 patients (92%) had decreased left ventricular ejection fraction (<50%) and all patients had wall motion abnormalities. A high SLE Disease Activity Index was the independent risk factor in the development of LM (odds ratio = 1.322, P < 0.001). With aggressive immunosuppressive therapies, most patients achieved satisfactory outcome. The in-hospital mortality was not significantly higher in the LM group than in the controls (4% vs. 2%,P = 0.491).
Conclusions: LM could result in cardiac dysfunction and even sudden death. High SLE disease activity might potentially predict the occurrence of LM at the early stage of SLE. Characteristic echocardiographic findings could confirm the diagnosis of LM. Early aggressive immunosuppressive therapy could improve the cardiac outcome of LM.