```json
{
	"no": ["no"], 
	"yes": ["yes"]
}
```
Based on the given feature, the possible values for feature nr_03 are 'no' and 'yes'. It appears that the values for this feature directly correspond to the target class. The value 'no' indicates that there are no paroxysms of atrial fibrillation in the patient's medical history, while the value 'yes' suggests the presence of such paroxysms. Therefore, if the feature value is 'yes', it implies that the patient does show chronic heart failure, and if the feature value is 'no', it implies the absence of chronic heart failure.