Assessment of sub clinical right ventricular ischaemia using oxygen sensitive cardiac Magnetic Resonance Imaging in patients with systemic sclerosis: Mechanistic insights from advanced cardiac imaging.

Abstract

Background: Cardiac involvement in Systemic Sclerosis (SSc) ranges from subclinical to life-threatening. Pulmonary arterial hypertension (PAH) occurs in 8-12% of SSc patients and remains a leading cause of death. The progressive decline in RV function in PAH is often attributed to RV ischaemia. Oxygen Sensitive Cardiac Magnetic Resonance imaging (OS-CMR) can directly visualise in-vivo myocardial deoxygenation. The objective of this study was to use OS-CMR to assess RV myocardial oxygenation in SSc patients prior to the onset of PAH. Methodology: SSc patients no known cardiac disease, stable PAH patients and healthy normal volunteers (NV) were prospective enrolled. All patients underwent a 3T CMR which included: cine images, rest/stress cine OS-CMR, native T1 mapping, rest/stress perfusion, and late gadolinium enhancement (LGE). The primary outcome was change in inferior RV OS-CMR signal intensity (SI). Two experienced independent reviewers performed the CMR analysis (inter-assessor correlation coefficient 0.8, 95% Cl [0.3, 0.9]). Results: A total of 44 patients (n=26 SSc; n=8 PAH; n=10 NV) were enrolled. The RV OS-CMR SI was significantly lower in the SSc group compared to the NV group (p=0.017). There was no significant difference between the PAH and SSc groups (p=0.426), indicating a similar degree of RV ischaemia in established PAH patients and SSc patients. Conclusion: SSc patients without PAH had similar RV ischaemia compared with PAH from other causes. Implying that in SSc, RV adverse effects occur prior to the onset of PAH, and that this effect is mediated by RV ischaemia secondary to changes in the microvasculature. Our findings may have screening and/or therapeutic implications.