Background/Purpose: Myocarditis is a life-threatening inflammatory disease increasingly reported in Systemic Sclerosis(SSc); the histological, clinical and prognostic features of SSc-myocardits have not been elucidated yet. We aimed to evaluate clinical, histological and prognostic features of SSc-myocarditis compared to patients with endomyocardial biopsy(EBM)-proven virus-negative myocarditis(VNM).

Methods: we enrolled 12 SSc patients with EBM-proven myocarditis(SSc-VNM), 12 patients with isolated VNLM(i-VNM) and 8 patients with VNLM in the context of other systemic autoimmune diseases(a-VNM), matched by age, gender and cardiovascular risk profile. On EMB, VNM was classified as acute, chronic and subacute, and the degree of fibrosis was scored as 0=absent,1=mild;2=moderate;3=severe. Clinical data, cardiac enzymes, echocardiogram, 24h-ECG-Holter and cardiac magnetic resonance(CMR), were obtained at baseline and at 3, 6 and 12 months, then during follow-up as clinically needed. Myocarditis-related complications(cardiac death, end-stage heart failure[HF], malignant arrhythmias or need for ICD-implantation) were recorded during a 1-year follow-up. Non parametric tests were used.

Results: clinical and demographic characteristics of our cohorts are represented in Table1. Clinical presentation did not statically differ between the 3 groups(p=ns), although dyspnoea class was significantly higher at presentation in SSc-VNLM patients compared to i-VNLM and a-VNLM (median 2 vs 0,p=0.047) and we found HF only in SSc-VNLM(25%). At CMR, myocardial oedema was more frequent in i-VNLM and a-VNLM, compared to SSc-VNLM(75% and 75% vs 8.3%,p=0.002), whereas late gadolinium enhancement(LGE) was present in all SSc-VNLM patients and in the majority of i-VNLM(87.5%) and a-VNLM(83.3%) patients(p=0.457). Levels of troponin T and NT-proBNP, left ventricular ejection fraction and number of ventricular ectopic beats on 24h-Holter did not differ between groups(p=ns). On EBM, acute myocarditis was diagnosed in 50% of both i-VNLM and SSc-VNLM patients, compared to 12.5% of a-VNLM patients(p=0.178); chronic myocarditis was diagnosed in 25% of both i-VNLM and SSc-VNLM patients, compared to 12.5% in a-VNLM patients(p=0.758), while subacute myocarditis was almost statically significantly more frequent in i-VNLM(75%), as compared to a-VNLM and SSc-VNLM patients(25% for both,p=0.063). The mean fibrosis score was significantly higher in SSc-VNLM patients(1.5±1.08) compared to a-VNLM(0.87±0.35) and i-VNLM(0.58±0.52)(p=0.046). As about the clinical outcome, the number of patients who died during follow-up due to cardiac complications (sudden cardiac death and HF) was significantly higher in SSc-VNLM patients(6 patients,50%), as compared to a-VNLM(0%) and i-VNLM(1 patient,8.3%)(p=0.006). Arrhythmic complications and need for ICD implantation were comparable between groups(25% and 8.3% in SSc-VNLM, 25% and 12.5% in a-VNLM, and 33.3% and 33.3% in i-VNLM,p=ns).

Conclusion: SSc-related myocarditis tends to present more frequently with HF and a higher dyspnoea class and to show higher degrees of fibrosis on EBM. These peculiar features are paralleled by a worst cardiac prognosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-sclerosis-myocarditis-has-unique-clinical-histological-and-prognostic-features-comparative-analysis-between-patients-with-endomyocardial-biopsy-proven-myocarditis/