Outcomes of myocarditis in systemic sclerosis: A 3-year follow-up.

Background and Objectives: The clinical course, the outcomes of myocarditis, and the imaging progression of cardiac magnetic resonance imaging (MRI) in systemic sclerosis (SSc) are still unknown. We aimed at defining changes in cardiac MRI findings, the clinical course, and the outcomes of SSc patients previously defined as having myocarditis by cardiac MRI. Methods: This prospective cohort study included SSc patients, who had previously been diagnosed with myocarditis through cardiac MRI at the Scleroderma Clinic of Khon Kaen University, between 2018 and 2020 and had had annual follow-ups of cardiac MRI for at least 3 years. Data on demographics, clinical characteristics, cardiac MRI findings, treatment regimens, and outcomes were collected. Serial cardiac MRI on a yearly basis was analyzed to assess changes in myocardial involvement over the 3-year period. Results: Ten SSc patients diagnosed with myocarditis via cardiac MRI were included. Most belonged to the diffuse cutaneous subset with a mean age of 58.3±8.6 years and were mildly symptomatic. Initial cardiac MRI findings showed myocardial edema and hyperemia in all patients and eight patients had had pre-existing myocardial scars, suggesting disease chronicity. Treatment for concomitant interstitial lung disease involved steroids with either cyclophosphamide or mycophenolate mofetil in 6 patients. Outcomes of myocarditis were stable, improving, and worsening in 4, 4, and 2 patients, respectively. There was no complete resolution of the cardiac MRI indices for myocarditis, and none had had major cardiac events. Conclusion: Although SSc myocarditis on cardiac MRI may improve or show stability, the changes remained persistent. Among patients with SSc and mildly symptomatic myocarditis, the efficacy of steroids and immunosuppressive therapy is inconclusive. Over a 3-year follow-up, the prognosis had been acceptably good with no cardiac events.