Subclinical myocardial inflammation and diffuse fibrosis are common in systemic sclerosis - a clinical study using myocardial T1-mapping and extracellular volume quantification

Background: Systemic sclerosis (SSc) is characterised by multi-organ tissue fibrosis including the myocardium. Diffuse myocardial fibrosis can be detected non-invasively by T1 and extracellular volume (ECV) quantification, while focal myocardial inflammation and fibrosis may be detected by T2-weighted and late gadolinium enhancement (LGE), respectively, using cardiovascular magnetic resonance (CMR). We hypothesised that multiparametric CMR can detect subclinical myocardial involvement in patients with SSc. Methods: 19 SSc patients (18 female, mean age 55 +/- 10 years) and 20 controls (19 female, mean age 56 +/- 8 years) without overt cardiovascular disease underwent CMR at 1.5T, including cine, tagging, T1-mapping, T2-weighted, LGE imaging and ECV quantification. Results: Focal fibrosis on LGE was found in 10 SSc patients (53%) but none of controls. SSc patients also had areas of myocardial oedema on T2-weighted imaging (median 13 vs. 0% in controls). SSc patients had significantly higher native myocardial T1 values (1007 +/- 29 vs. 958 +/- 20 ms, p < 0.001), larger areas of myocardial involvement by native T1 > 990 ms (median 52 vs. 3% in controls) and expansion of ECV (35.4 +/- 4.8 vs. 27.6 +/- 2.5%, p < 0.001), likely representing a combination of low-grade inflammation and diffuse myocardial fibrosis. Regardless of any regional fibrosis, native T1 and ECV were significantly elevated in SSc and correlated with disease activity and severity. Although biventricular size and global function were preserved, there was impairment in the peak systolic circumferential strain (-16.8 +/- 1.6 vs. -18.6 +/- 1.0, p < 0.001) and peak diastolic strain rate (83 +/- 26 vs. 114 +/- 16 s-1, p < 0.001) in SSc, which inversely correlated with diffuse myocardial fibrosis indices. Conclusions: Cardiac involvement is common in SSc even in the absence of cardiac symptoms, and includes chronic myocardial inflammation as well as focal and diffuse myocardial fibrosis. Myocardial abnormalities detected on CMR were associated with impaired strain parameters, as well as disease activity and severity in SSc patients. CMR may be useful in future in the study of treatments aimed at preventing or reducing adverse myocardial processes in SSc.