Pancarditis and fibrosis as hallmarks of lupus myocarditis: clinical features, imaging findings and outcomes

OBJECTIVES: To describe and compare the clinical features, imaging findings and outcomes of lupus myocarditis (LM) patients with those of active systemic lupus erythematosus (SLE) without myocarditis (SLE-non-LM) and acute myocarditis non-autoimmune (AM-non-AI) patients. METHODS: This was a retrospective cohort study including 32 LM patients diagnosed between 2005 and 2022, matched 1:1 by age and sex with active SLE-non-LM and AM-non-AI groups. SLE patients (EULAR/ACR 2019) had clinically suspected myocarditis by European Society of Cardiology criteria, confirmed by cardiac magnetic resonance (CMR) imaging (Updated Lake Louise criteria). Clinical, laboratory, electrocardiographic, echocardiographic and CMR findings, as well as outcomes, were compared across groups with a 2-year follow-up. RESULTS: LM patients presented with higher rates of fever and cardiogenic shock compared with AM-non-AI. Echocardiography revealed significantly more wall motion abnormalities (71.9% vs 25.0%, P < 0.001), reduced left ventricular ejection fraction (56.3% vs 18.8%, P = 0.002), pulmonary hypertension (37.5% vs 3.1%, P = 0.001) and valvular abnormalities (65.5% vs 3.1%, P < 0.001). On CMR, LM patients had a higher prevalence of late gadolinium enhancement (65.6% vs 37.5%, P = 0.024) and higher rates of pericardial involvement and valvular regurgitation. Pancarditis was identified exclusively in LM patients (65.6% vs 0%, P < 0.001). Outcomes were worse in LM, with increased ICU admission (28.1% vs 6.3%, P = 0.043) and invasive mechanical ventilation (25.0% vs 3.1%, P = 0.027). However, 2-year mortality was comparable between LM and AM-non-AI groups. CONCLUSION: LM is a distinct and severe phenotype of SLE, characterized by pancarditis and unique imaging features. Echocardiography and CMR are pivotal in early recognition, with prognostic implications.