Based on the given feature "nr_04", which represents a persistent form of atrial fibrillation in the patient's medical history, we can analyze its relationship with the presence of chronic heart failure as the target variable.

Since chronic heart failure is the target variable, we can assume that the feature "nr_04" might be an important factor in determining the presence of chronic heart failure. However, without further domain-specific knowledge or a dataset to analyze, we cannot definitively state the relationship between the feature and the target.

Now, let's create a dictionary with the possible values of feature "nr_04" for each target class.

```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```

Please note that in this case, we only have two categories for the feature "nr_04" ("no" and "yes"). We include both categories in the dictionary, assuming that they cover all possible values of the feature.