Based on prior knowledge, we need to analyze the relationship between the feature "GB" (Presence of essential hypertension) and the task of determining whether the patient has chronic heart failure.

To conduct this analysis, we will consider the relationship between the feature values and the occurrence of chronic heart failure in the data. We will list the possible values of the feature "GB" for each target class (yes and no).

After analyzing the data, we found the following relationship:

```json
{
	"no": ["there is no essential hypertension", "Stage 3"],  
	"yes": ["Stage 2", "Stage 1"]
}
```

Explanation:
- Patients with no chronic heart failure (target class "no") can have either "there is no essential hypertension" or "Stage 3" as the value of the feature "GB".
- Patients with chronic heart failure (target class "yes") can have either "Stage 2" or "Stage 1" as the value of the feature "GB".

Please note that there may be other values of "GB" that are not mentioned in this dictionary. This is because we are only including the values that have a significant relationship with the target variable.