Evaluate the Effect of Injectable Neucardin on the Cardiac Function of Subjects With Chronic Systolic Heart Failure

Inclusion Criteria: 1. Aged 18-75 years, male or female; 2. Confirmed diagnosis of heart failure, in stable condition currently, NYHA class II-III, left ventricular ejection fraction (LVEF)≤40% (measured by echocardiography with modified Simpson's method at Screening 1, and measured by CMR at Screening 2 and baseline); 3. Male NT-proBNP ≤1700 pg/ml or female NT-proBNP≤4000 pg/ml (detected by Roche kit in the central laboratory at screening 1); 4. Receiving standard basic therapeutic medication for heart failure for more than 3 months, at the target dose or maximum tolerated dose for more than 1 month, or no change in dose within the last 1 month; 5. Understand and sign the informed consent form. Exclusion Criteria: 1. Atrial fibrillation during the screening period; 2. Conditions limiting CMR examination, such as installation of pacemakers, ICDs, CRTs or other similar devices contraindicated for CMR, or have claustrophobia; 3. Hypertrophic cardiomyopathy with outflow tract obstruction, constrictive pericarditis, significant and uncorrected valvular heart disease (severe regurgitation or severe stenosis or valvular disease requiring surgery), congenital heart disease requiring surgery but not yet undergoing surgical treatment, primary pulmonary hypertension or secondary severe pulmonary hypertension (≥ 70 mmHg); 4. Right heart failure due to lung disease; 5. Subjects with chronic heart failure complicated with acute hemodynamic disturbance or acute decompensation within recent 1 month (symptoms and signs indicate chronic heart failure is aggravated, and intravenous drug therapy may be required); 6. Angina pectoris within 3 months; 7. Myocardial infarction within the past 6 months; 8. Cerebrovascular accident, revascularization (PCI or other surgery), cardiac surgery, carotid artery or other large vessel surgery within the past 6 months; 9. Prepare to install pacemaker, ICD, CRT or other similar devices within 6 months; 10. History of heart transplantation, use of ventricular assist device (VAD) or preparation for heart transplantation, VAD; 11. Diagnosis of peripartum or chemotherapy-induced cardiomyopathy within the past 12 months; 12. Serious arrhythmia (sustained ventricular tachycardia or other conditions meet the criteria according to the investigator's judgement ); 13. Clinical diagnosis of pericardial effusion, pleural effusion or B ultrasound showed pericardial effusion (greater than 50ml or 3 mm) or pleural effusion (greater than 200ml or 10 mm); 14. Liver or kidney dysfunction, chronic liver disease may have a potential impact on liver function, non-heart failure induced bilirubin or alkaline phosphatase \> 2 times the upper limit of normal, aspartate aminotransferase or alanine aminotransferase \> 3 times the upper limit of normal, eGFR calculated using the MDRD method \< 30 ml/min/1.73m2 ; 15. Systolic blood pressure \< 90 mmHg or \> 160 mmHg; 16. Blood K + \< 3.2 mmol/L or \> 5.5 mmol/L; 17. Subjects with an absolute change in LVEF \> 5% as detected by CMR between screening 2 and baseline; 18. Women of childbearing age who are planning to become pregnant within 2 years (women of childbearing age are defined as all women with physiological capability to become pregnant), and pregnant or lactating women; 19. Patients whose survival time is expected to be less than 6 months as judged by the investigator; 20. Those who have participated in any drug clinical trial within the previous 3 months; 21. Severe neurological disorders (Alzheimer's disease, progressive parkinsonism); 22. The subjects with tumor history or is suffering from tumor now, or with precancerous lesions confirmed by pathological examination (such as breast ductal carcinoma in situ, or cervical dysplasia), or with malignant mass found by examination (physical examination, X-ray examination or B ultrasound examination or other means); 23. The subjects with proliferative glands or adenomas that are found to have endocrine activity that affects cardiac function or endocrine function detected by examinations (physical examination, X-ray examination, B ultrasound examination or other means), such as pheochromocytoma, thyromegaly, etc. (patients with euthyroid thyroid or normal thyroid function do not need to be excluded); 24. The subject, in the judgment of the Investigator, is unable to complete the study or to comply with the requirements of the study (for administrative or other reasons).