Cardiac magnetic resonance imaging before and after therapeutic interventions for systemic sclerosis-associated myocarditis

Objectives Cardiac magnetic resonance imaging (CMRI) is increasingly used to evaluate cardiac involvement in SSc. We assessed changes, including inflammatory and/or fibrotic myocardial lesions detected by CMRI, following therapeutic interventions for SSc-associated symptomatic myocarditis. Methods In this retrospective study, myocarditis was diagnosed by CMRI (2018 revised Lake Louise criteria) in 14 diffuse and 4 limited SSc patients [16/18 women, age 56 years (s.d. 11), disease duration 8 years (s.d. 11), 17/18 with lung involvement] with cardiac symptoms and abnormal findings on echocardiography (4/18) and/or in 24-hour Holter monitoring (12/14). CMRI was repeated after 8 months (s.d. 3) following administration of cyclophosphamide (n = 11, combined with corticosteroids in 3 and rituximab in 1), mycophenolate (n = 1), tocilizumab (n = 1), methotrexate/corticosteroids (n = 2), corticosteroids (n = 1) or autologous stem cell transplantation (n = 2). Results Functional cardiac improvement was evident by increases in left [by 5.8% (s.d. 7.8), P = 0.006] and right ventricular ejection fraction [by 4.5% (s.d. 11.4), P = 0.085] in the second CMRI compared with the first. Notably, late gadolinium enhancement, currently considered to denote replacement fibrosis, decreased by 3.1% (s.d. 3.8; P = 0.003), resolving in six patients. Markers of myocardial oedema, namely T2 ratio and T2 mapping, decreased by 0.27 (s.d. 0.40; P = 0.013) and 6.0 (s.d. 7; P = 0.025), respectively. Conversely, both T1 mapping, considered to reflect acute oedema and diffuse fibrosis, and extracellular volume fraction, reflecting diffuse fibrosis, remained unchanged. Conclusions CMRI may distinguish between reversible inflammatory/fibrotic and irreversible fibrotic lesions in SSc patients with active myocarditis, confirming the unique nature of primary cardiac involvement in SSc. Whether, and how, CMRI should be used to monitor treatment effects in SSc-associated myocarditis warrants further study.