{
  "abstract": "Introduction Primary cardiac involvement in systemic sclerosis (SSc-pHI) contributes significantly to mortality, accounting for roughly 12 % of SSc-related deaths. Clinical prevalence varies widely from 7% to 39% depending on the criteria and diagnostic modalities. Typical manifestations include arrhythmias (atrioventricular block, supraventricular and ventricular tachyarrhythmias), systolic or diastolic heart failure, myocarditis, pericardial disease, valvular lesions, and myocardial fibrosis. Diagnosis relies on echocardiography, cardiac biomarkers, Holter monitoring, and particularly cardiac magnetic resonance (CMR), which is the gold standard for detecting inflammation and fibrosis.Recent EULAR guidelines (2024/2025) incorporate targeted therapies for fibrotic manifestations and pulmonary arterial hypertension in SSc, yet still lack specific guidance concerning primary cardiac involvement.Material and Methods We describe two patients with SSc who presented with skeletal muscle involvement (confirmed myopathy), interstitial lung disease (ILD), and myocardial involvement demonstrated by CMR, indicating inflammatory changes (prolonged native relaxation time and late gadolinium enhancement). Both were positive for anti-PM/Scl-100 antibodies, a feature associated with scleromyositis, where anti-PM/Scl positivity occurs in up to 13% of SSc cases and up to ~31% of scleromyositis patients. Anti-PM/Scl antibodies correlate with more frequent muscle involvement, ILD, and occasionally cardiac manifestations.Results Clinically, both patients showed elevated levels of cardiac biomarkers (troponin T, NT-proBNP) and arrhythmias. Myocarditis was confirmed through CMR. Based on recent evidence, combination therapy with rituximab (RTX, 2 x 1000 mg with a two-week gap and a repeat dose after six months) and mycophenolate mofetil (MMF, 2 g/day) was started, following regimens mainly used for SSc-ILD. After 6–12 months, both patients experienced normalization of troponin T, reductions in NT-proBNP, and fewer arrhythmias, consistent with published data. Follow-up CMR showed no active myocardial inflammation.Conclusions In complex SSc cases involving cardiac, muscular, and pulmonary domains — especially with PM/Scl-100 positivity — combined MMF and RTX therapy appears effective. The absence of specific recommendations in current EULAR guidelines for cardiac involvement highlights an unmet clinical need. Given the frequency of cardiac manifestations (7–39 %) and their significant prognostic impact, this therapeutic approach deserves further consideration.",
  "authors": [
    {
      "affiliations": [
        "Department of Rheumatology, Clinical Immunology, Geriatrics and Internal Medicine, Medical University of Gdansk, Poland, Gdansk, Poland"
      ],
      "name": "Monika Gos"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Clinical Immunology, Geriatrics and Internal Medicine, Medical University of Gdansk, Poland, Gdansk, Poland"
      ],
      "name": "Anna Wojteczek"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Clinical Immunology, Geriatrics and Internal Medicine, Medical University of Gdansk, Poland, Gdansk, Poland"
      ],
      "name": "Michal Chmielewski"
    }
  ],
  "title": "P.139 Myocarditis in systemic sclerosis patients with positive anti-PM/Scl-100 antibodies: two cases treated with combination therapy of mycophenolate mofetil and rituximab",
  "uid": "2c0306ca-8193-53db-8f43-1408270208fe"
}