```json
{
    "no": ["no"],
    "yes": ["yes"]
}
```
Based on the given feature description, we can analyze the relationship between the feature "endocr_03" (Thyrotoxicosis in the anamnesis) and the task of determining if the patient has chronic heart failure. Since the feature is binary, it can take two possible values: "no" and "yes".

In relation to the task, we can consider the following possibilities:
- If the feature value is "no", it suggests that there is no history of Thyrotoxicosis in the patient's medical history. In this case, it is likely that the patient does not have chronic heart failure.
- If the feature value is "yes", it indicates that the patient has a history of Thyrotoxicosis. This may contribute to the development or presence of chronic heart failure.

Therefore, it is important to consider the values of the feature "endocr_03" when determining the presence of chronic heart failure. The provided dictionary reflects the possible values of the feature for each target class ("no" and "yes") for chronic heart failure.