Heart failure is a complex group of clinical syndromes in which the filling or ejection capacity of the ventricles is impaired due to structural or functional abnormalities of the heart. As the end stage of many cardiovascular diseases, heart failure has become the last battleground for cardiovascular physicians in the 21st century due to its high incidence and lower 5-year survival rate for patients with clinical symptoms than for common malignancies. Even with the standard treatment protocols recommended by current guidelines, the rehospitalization rate and morbidity and mortality rates of heart failure patients are still at high levels. In China, the number of patients with heart failure is 1-2% of the total population. Not only does heart failure significantly reduce the quality of life of patients and impose a great economic burden on their families and society, but it also poses a high risk of death. 1. What is the vulnerable period of heart failure Although most heart failure patients can be discharged with significant improvement in symptoms and signs after systematic treatment during hospitalization, the patient’s heart function damage is still not fully recovered during this period out of instability, and there is still a possibility of recurrence in the early stage after discharge. Two to three months after discharge, heart failure patients have to go through a “vulnerable period”. The vulnerable period, as the name implies, is an extremely dangerous time for the patient and should be taken seriously as they are prone to re-hospitalization. Numerous studies have shown that exacerbation of cardiac insufficiency is an important pathophysiological basis for death or hospital readmission in heart failure patients during the vulnerable period. In addition, heart failure patients with acute episodes of cardiac insufficiency usually require intensive in-hospital treatment with intravenous vasoactive drugs, which are gradually reduced until discontinued when cardiac function improves, and evidence-based oral medications are started. The fact that oral medications are still in the adjustment phase in patients with heart failure during the vulnerable period is another reason for the higher risk of adverse events. The treatment regimen during this period has a critical impact on the long-term prognosis of heart failure patients. Optimizing the treatment regimen during this period may better improve the patient’s cardiac function and reduce the risk of follow-up, while delaying the initiation of effective drug therapy may lead to a poor prognosis. 3. How to deal with the risk For patients with heart failure, physicians need to assess their organ function, consider the coexistence of multiple diseases, pay attention to the synergistic drug response, and start treating heart failure from the primary cause. In addition, for patients who already have symptoms of heart failure and potential heart failure, it is recommended to: (1) find a regular cardiologist (someone who has experience in heart failure treatment) to keep an eye on the changes of heart structure and function throughout the whole process, and to guide related treatment, cardiac rehabilitation and chronic disease management; (2) have regular cardiac ultrasound to understand whether the heart is enlarged and developing, once every 3-6 months, preferably with the same cardiac ultrasonographer; have regular (3) Patients with heart failure symptoms are advised to have BNP testing regularly to guide their heart function, which can better prevent symptomatic heart failure attacks or recurrence. After discharge from hospital, heart failure patients should pay attention to regular medication, water and salt restriction, monitoring of their condition, and moderate exercise; for heart failure symptoms, patients must be detected early, intervene early, treat early, and focus on prevention rather than mending after the occurrence of heart failure to get twice the result with half the effort as possible.