Objective: To explore the effect of case management-based extended intervention model on treatment compliance and cardiac function in patients with chronic heart failure. Methods: This study retrospectively analysed the clinical data of 203 patients with chronic heart failure at Xingtai Third Hospital from January 2019 to January 2022. In accordance with different intervention programs, the patients were divided into a study group (SG, n = 102) and a reference group (RG, n = 101). The SG received the extended intervention model based on case management, and the RG adopted the conventional intervention model. Comparison was conducted on the treatment compliance, cardiac function, activity of daily living scale (ADL) scores and readmission rates in both groups. Results: After intervention, the SG showed higher treatment compliance (p < 0.05), lower heart rate, higher left ventricular ejection fraction, ratio of transmitral peak rapid filling velocity to transmitral peak atrial filling velocity at mitral orifice and six-minute walk distance (p < 0.001) and significantly lower ADL score and readmission rates than the RG (p < 0.05). Conclusion: The extended intervention model based on case management positively influences the treatment compliance of patients with chronic heart failure and continuously improves patients' cardiac function, reduces the readmission rate, enhances daily living ability, comprehensively increases clinical efficacy and benefits patients for a long period.