Based on prior knowledge, premature ventricular contractions (PVCs) are abnormal heartbeats that originate in the lower chambers of the heart (ventricles). PVCs can be a sign of heart disease or other cardiac conditions, including chronic heart failure.

To analyze the relationship between the feature "nr_02" and the task of determining if the patient shows chronic heart failure, we need to examine how the presence of premature ventricular contractions (PVCs) in the patient's anamnesis (medical history) relates to chronic heart failure.

Possible scenarios:
1. If the patient has a history of PVCs (nr_02 = 'yes'), it is more likely that they could have chronic heart failure.
2. If the patient has no history of PVCs (nr_02 = 'no'), it does not automatically mean they do not have chronic heart failure, as other factors could contribute to the condition.

Based on this analysis, here is the dictionary with the possible values of feature nr_02 for each target class:

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

Please note that in this case, since nr_02 is a categorical variable with only two possible categories ('no' and 'yes'), the dictionary includes one possible value for each target class.