Heart failure, one of the leading causes of connective tissue disease (CTD) mortality, has attracted increasing attention. Currently, no known study had focused on the effect of sacubitril/valsartan on right ventricular dysfunction and in the systemic disease induced heart disease. We aimed to observe the effect of sacubitril/valsartan on primary endpoints (6 minutes walking test and myocardial fibrosis) in CTD patients with right ventricular ejection fraction reduction (RV-HFrEF).

Patients with CTD frequently exhibit multi-organ pathophysiological and functional damage. Heart failure, one of the leading causes of CTD mortality, has attracted increasing attention. Mostly, patients with CTD present with nonspecific cardiac symptoms, normal ECG, and preserved left ventricular ejection fraction (LVEF) and therefore do not receive an early cardiac diagnosis and treatment. Pulmonary arterial hypertension (PAH), right ventricular (RV) dilatation and hypertrophy might become the first and the most frequent cardiac findings. Sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitors, is a "superstar" which inhibits both neprilysin and renin-angiotensin aldosterone system that closely related to the heart failure mechanism. It has been strongly recommended as class I drug in treating the patient with chronic HFrEF from 2017 ACC/AHA/HFSA heart failure guideline for the ability of dramatically reduce the cardiovascular mortality rate.

Cardiovascular magnetic resonance (CMR) is able to depict myocardial characteristics from structure to tissue properties using cine and late gadolinium enhancement (LGE) sequences. Newly developed imaging studies to date include T1 mapping and T1-derived extracellular volume estimation. All the previous studies in CTD have been restricted to patients with advanced cardiac involvement.

Together with clinical assessment and multi-imaging tests, the aim of the present study is going to observe the effect of sacubitril/valsartan on primary endpoints (6 minutes walking test and myocardial fibrosis) in CTD patients with RV-HFrEF.

Inclusion Criteria:

• Age between 18-75 years old.
• confirmed CTD（including systemic lupus erythematosus, myositis, polymyositis, systemic sclerosis, sarcoid, Sjögren's syndrome or mixed connective tissue disease）
• SLEDAI ≤ 6 in patients with SLE or ESR ≤ 30 in patients with SSc
• already have OPT for CTD at least 3 month
• RVEF ≤ 45%
• Providing written informed consent

Exclusion Criteria:

• Documented coronary artery disease or prior angiography for coronary artery disease (>50% stenosis).
• Patients with known congenital heart disease or other systemic diseases that might induce RVrEF.
• Patients with standard metallic contraindications to CMR or an estimated glomerular filtration rate < 30 ml/min/1.73 m2.