Distinctive clinical traits of lupus-related myocarditis: a multicentre retrospective study.

Objectives: Cardiovascular involvement in systemic lupus erythematosus (SLE) is frequent but little is known about possible distinctive traits of SLE-related myocarditis (myoSLE) in comparison to patients with SLE (onlySLE) or myocarditis alone (onlyMyo).
Methods: A retrospective analysis was performed comparing patients with myoSLE (n = 25) from three centres with consecutive patients with onlySLE (n = 279) and onlyMyo (n = 88). SLE patients were dichotomised by disease duration ≤1 vs >1 year into recent onlySLE/early myoSLE vs longstanding onlySLE/late myoSLE. Further stratification into disease duration of 1-5, 5-10 and >10 years was also performed. SLE disease activity index 2000 (SLEDAI-2K) was used to estimate disease activity. Myocarditis was diagnosed through biopsy or magnetic resonance.
Results: Women were significantly more frequent among myoSLE than among onlyMyo (72% vs 43%; p= 0.013). Compared with onlyMyo, myoSLE patients had a higher frequency of conduction abnormalities (22% vs 5%; p= 0.046) and presented with numerically higher frequencies of left ventricular function compromise (48% vs 30%), along with higher pro-brain natriuretic peptide levels. Inflammation markers were higher in myoSLE compared with onlyMyo and to patients with onlySLE with >10 years of disease duration. SLEDAI-2K was significantly higher in late myoSLE than in longstanding onlySLE. Antiphospholipid syndrome was more frequent in myoSLE than in onlySLE. Multivariate analysis showed an association among myoSLE, anti-beta-2-glycoprotein I antibodies (aB2GPI, p= 0.014) and a higher number of involved British Isles Lupus Assessment Group domains in patient history (p= 0.003).
Conclusion: myoSLE has unique clinical traits compared with other forms of myocarditis and is associated with aB2GPI and a more severe SLE course.
(© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)