Background/Purpose: Myocardial involvement is a significant contributor to mortality in patients with Systemic Sclerosis (SSc). The objective of this study was to analyze the clinical characteristics of SSc patients with myocardial involvement (MI) and assess their outcomes after treatment modifications.

Methods: We conducted a retrospective study involving patients who met the ACR/EULAR 2013 Scleroderma criteria and were diagnosed with non-ischemic myocarditis. The study period spanned from July 2010 to May 2023. Cardiac MRI (CMR) scans were primarily conducted to evaluate cardiovascular symptoms, as well as to investigate abnormal findings in echocardiography and/or Holter monitoring.

Results: Our study included a total of 18 female SSc patients, diagnosed with non-ischemic myocarditis following CMR. The mean age at diagnosis was 50.6 years (SD 14.3), with a mean disease duration of 9.7 years (SD 7.3). The follow-up period since MI diagnosis was 3.6 years (SD 3). Notably, half of the patients (9/18) had early-stage disease, diagnosed within three years from the onset of SSc. No significant differences were found in the clinical characteristics between the two MI groups (early vs. established SSc), except for a slightly higher occurrence of gastrointestinal involvement noted in the early SSc group (p=0.058).Echocardiography performed at the time of MI diagnosis, revealed a slightly lower ejection fraction in patients with established SSc compared to those with early SSc (EF=55.6, SD 9.7 vs EF=60.6, SD 5.3), but this difference did not reach statistical significance. Diastolic dysfunction was identified in only three patients. Conversely, abnormal findings on 24-hour Holter monitoring were observed in 9 out of 18 patients (5/9 patients with early SSc). Regarding treatment modifications, 5 patients received cyclophosphamide as the initial treatment regimen for SSc myocarditis, while 10 patients were treated with rituximab. Concomitant use of corticosteroids was observed in 11 patients. In 6 out of the 18 patients, a second CMR was performed. The interval between the initial and second MRI varied, with a one-year interval in 4 patients, a 5-year interval in 1 patient, and a 10-year interval in 1 patient. Among these patients, myocarditis had resolved in 2 cases, both of whom were receiving a combination of Rituximab and corticosteroids. Improvement in T2-weighted parameters (T2 ratio), reflecting decrease of myocardial oedema, was observed in other 2 cases, undergoing combination therapy with rituximab and mycophenolate mofetil. Surprisingly, the remaining 2 patients who had initially received cyclophosphamide as the treatment for myocardial involvement showed no change in the cardiac MRI parameters.

Conclusion: The results of our study align with the theory that myocardial involvement in SSc can occur in both early and long-standing disease. The findings highlight the significance of early detection of SSc patients with myocarditis, as there is evidence suggesting that some patients may experience resolution of myocardial lesions. However, further studies are needed to determine the most appropriate treatment regimen and to investigate the potential use of cardiac MRI as a monitoring tool for treatment response.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/assessment-of-systemic-sclerosis-associated-myocarditis-a-single-center-case-series-study/