Clinical Features and Associated Factors of Lupus Myocarditis: A Case‐Control Study

OBJECTIVES: This study aimed to explore the clinical characteristics of patients with lupus myocarditis (LM) and to evaluate the efficacy of rituximab (RTX) in LM treatment. METHODS: The medical records of all patients with LM admitted to our hospital between January 2012 and March 2025 were retrospectively analyzed. Two control groups were established by randomly matching patients by sex and age at a 1:1 ratio: patients with systemic lupus erythematosus (SLE) without LM and patients with non-SLE myocarditis. The SLE disease activity index 2 K (SLEDAI 2 K) score and Systemic Lupus Erythematosus Disease Activity Score (SLE-DAS) were calculated to evaluate SLE disease activity. RESULTS: A total of 22 patients with LM were enrolled. Patients with LM had a higher incidence of lupus nephritis and a higher positivity rate for anti-SSB antibodies than those with SLE without LM. Furthermore, patients with SLE with LM had significantly higher SLE-DAS than those without LM, although no statistical difference in SLEDAI 2 K score was observed between the groups. Wall motion abnormalities, valvular regurgitation, and decreased left ventricular ejection fraction (LVEF) were more frequent in patients with LM than in those with non-SLE myocarditis. All patients with LM received corticosteroid treatment, with three of them receiving RTX in addition to standard therapy. With a median follow-up of 4 (range, 1-24) months, 2 patients (9.1%) died due to heart failure, and the remaining 20 achieved symptom remission. Moreover, 13 patients underwent follow-up echocardiography, which showed a significant improvement in LVEF. The three patients treated with RTX achieved clinical improvement within a mean of 2 weeks, enabling rapid glucocorticoid tapering. CONCLUSIONS: Patients with LM more frequently present with lupus nephritis and positive anti-SSB antibodies, are more likely to have echocardiographic abnormalities, and exhibit a higher mortality rate. In addition, RTX is a promising drug for LM treatment.