Clinical spectrum and outcomes of pericardial and myocardial disease in systemic sclerosis: a multicentre case series and literature review

Objectives: Cardiac involvement is a leading cause of morbidity and mortality in systemic sclerosis (SSc) yet is often underdiagnosed. Early recognition is crucial but published data remains limited. This study aimed to characterize the clinical presentation, diagnostic features, and outcomes of SSc patients with acute primary heart involvement. Methods: This multicentre retrospective case series included patients meeting the 2013 ACR/EULAR SSc classification criteria with clinically significant pericardial effusion or myocardial involvement, identified across tertiary rheumatology centres in Portugal (Coimbra, Lisbon, and Porto) and Spain (León). A complementary literature review was performed to identify additional published cases. Results: Of 23 screened cases, 6 met the inclusion criteria. The literature review identified 13 additional reports, totalling 19 patients. In 8 (42.1%) of patients, heart involvement was either the initial manifestation or occurred concurrently with the diagnosis of SSc. Pericardial disease (n=6) often presented as tamponade requiring emergent pericardiocentesis. Myocardial involvement (n=13) was classified as acute myocarditis (AM) in 9 (69.2%) and chronic inflammatory cardiomyopathy (CIC) in 4 (30.8%). Cardiac magnetic resonance showed late gadolinium enhancement in 9 (72.7%) and myocardial oedema in 4 (36.4%); however, both were absent in two biopsy-confirmed AM cases. Cyclophosphamide was the second most common therapy after corticosteroids. Two patients died during hospitalization, with three more deaths during long-term follow-up. Conclusion: Severe cardiac manifestations in SSc frequently occur early in the disease, presenting as tamponade or myocardial involvement. Reliance solely on imaging may lead to myocarditis underdiagnosis. Distinct clinical profiles between AM and CIC point toward separate phenotypes with unique prognostic and therapeutic considerations. Large-scale, prospective studies are essential to refine early diagnostic approaches and optimize treatment.