Characterization of the Left Ventricular Myocardium in Systemic Sclerosis

Background/Objectives: Cardiac involvement in systemic sclerosis (SSc) ranges from subclinical to severe. While pulmonary artery hypertension (PAH) is well-documented, the mechanism of left ventricular (LV) ischemia remains unclear. Oxygen-sensitive cardiovascular magnetic resonance (OS-CMR) imaging offers a novel approach to assessing myocardial oxygenation and ischemia. This study evaluated the changes in myocardial deoxygenation in response to stress using LV OS-CMR in SSc patients without known cardiac disease. Methods: We prospectively recruited SSc patients without prior cardiac disease or risk factors, and age- and sex-matched healthy volunteers (HVs). All participants underwent transthoracic echocardiography (TTE) and 3T CMR, including native T1 mapping, rest/stress OS-CMR, stress perfusion, and late gadolinium enhancement (LGE). The primary outcome was a change in the LV OS-CMR signal intensity (SI) after adenosine stress. Results: Thirty-three participants (23 SSc, 10 HV) were enrolled. SSc patients had significantly lower global LV OS-CMR SI compared to HV (13.4 ± 6.5 vs. 19.5 ± 3.6, p = 0.011). OS-CMR SI change ≤ 10% was observed in at least one segment in 20 (87%) SSc patients and globally in 12 (52%). LGE was present in 5 (22%) patients, and 18 (78%) had ≥1 abnormal T1 mapping segment. LV global longitudinal strain (GLS) was reduced in SSc patients compared to the HVs (-19.04 ± 3.86 vs. -21.92 ± 3.72, p = 0.045). All HVs had normal CMR and TTE findings. Conclusions: SSc patients without known cardiovascular disease or PAH demonstrated subclinical LV ischemia with an impaired myocardial oxygenation response to stress. They further demonstrated LV myocardial deformation abnormalities and LV diffuse fibrosis when compared to an age-matched control group. Our findings support the presence of early coronary microvascular dysfunction and LV myocardial fibrosis in this population, which may explain the adverse cardiovascular risk seen in this population, independent of the presence of PAH.