A Prospective, Single-center, Randomized Controlled Clinical Study Evaluating the Efficacy and Safety of Hyperbaric Oxygen Therapy as an Adjunctive Treatment for Chronic Heart Failure

1. Study Design This is a prospective, single-center, randomized controlled clinical trial designed to evaluate the efficacy and safety of hyperbaric oxygen therapy as an adjunctive treatment for chronic heart failure. 2. Randomization After confirming eligibility, participants will be randomized in a 1:1 ratio via a web-based randomization system into either the experimental group (hyperbaric oxygen therapy plus standard medication) or the control group (standard medication alone). 3. Treatment Protocol Patients diagnosed with chronic heart failure at the center, who meet the criteria and have no absolute contraindications for hyperbaric oxygen therapy, will be enrolled. Specifically, the study will enroll patients with Heart Failure with Reduced Ejection Fraction (HFrEF, EF ≤40%) as per the latest guidelines. Experimental Group: Participants will receive hyperbaric oxygen therapy in addition to stable, guideline-directed medical therapy based on the "New Four Pillars" (ARNI/ACEI/ARB + Beta-blocker + MRA + SGLT2 inhibitor). Control Group: Participants will receive only the standard guideline-directed medical therapy ("New Four Pillars" as above) for chronic heart failure. All other aspects of care are identical to the experimental group, except for the hyperbaric oxygen therapy. Given that chronic heart failure requires long-term management, the hyperbaric oxygen protocol is divided into three courses to consolidate and maintain efficacy, as well as to improve patients' oxygen reserve capacity and tolerance. Each course consists of 10 sessions, with a one-month interval between courses. The hyperbaric oxygen treatment will be administered in a multi-place chamber at a pressure of 0.2 MPa (2 ATA). The session protocol is as follows: 20 minutes of compression, followed by two 30-minute periods of oxygen inhalation via mask, separated by a 10-minute air break, and finally 20 minutes of decompression. The total duration per session is 110 minutes. Sessions are conducted 5 times per week, making the total duration of each treatment course 14 days. 4. Follow-up After randomization and initiation of treatment, clinical follow-up visits will be conducted to collect data. For the experimental group, follow-ups will occur one day after the completion of each hyperbaric oxygen course. All participants (both groups) will undergo additional follow-ups at 3 months, 6 months, and 12 months after the complete hyperbaric oxygen treatment regimen.