The clinical feasibility of 18F-FMBG cardiac PET imaging will be observed in sympathetic nervous system activity in patients with heart failure, predicted cardiac events, guided ICD implantation, and evaluated therapy efficiency.

This is a prospective, single-center clinical study, using18F-meta-fluorobenzylguanidine (18F-MFBG) cardiac PET imaging to present the sympathetic nerve status in heart failure, including ICD implantation. Through follow-up, we analyze the correlation between the distribution of the tracer in the heart and the functions and progression of the patients, including the occurrence of ventricular arrhythmias and sudden cardiac death, And further investigate the guiding value of 18F-MFBG cardiac sympathetic nerve imaging in the screening of ICD implantation patients, including primary and secondary prevention, reducing the cost of ICD implantation and related complications. Furthermore, to evaluate the therapy efficacy for these patients with heart failure using 18F-MFBG cardiac imaging has been considered.

Inclusion Criteria:

• 1. Clinically confirmed patient with chronic heart failure, LVEF ≤ 40%, cardiac function NYHA 2-3 grade, survival period greater than 1 year, evaluated by the Heart Failure Center of Sichuan Provincial People's Hospital.
• 2. Chronic heart failure patients were evaluated by the Cardiology Department of Sichuan Provincial People's Hospital 5-10 days before ICD implantation.
• 3. All patients above have signed an informed consent form.

Exclusion Criteria:

• 1. Heart failure, heart function NYHA levels ⅠOR Ⅳ.
• 2. The patient has already implanted ICD or CRT.
• 3. Heart transplant patients.
• 4. Patients with malignant tumors.
• 5. Heart valve disease.
• 6. Myocardial infarction occurred within the past three months.
• 7. The patient has contraindications for ICD implantation surgery.
• 8. The patient does not cooperate or is unwilling to conduct the study.

enrolling patients with chronic heart failure with a heart function of NYHA Class II-III.