Based on my prior knowledge, paroxysms of atrial fibrillation in the anamnesis (feature nr_03) can be a potential risk factor for chronic heart failure. Atrial fibrillation is a common arrhythmia that can lead to the development and progression of heart failure over time. Therefore, it is possible that patients with a history of atrial fibrillation paroxysms (nr_03 = 'yes') may have a higher likelihood of developing chronic heart failure.

Here is the analysis of the relationship between the feature nr_03 and the occurrence of chronic heart failure:

- If the patient has a history of paroxysms of atrial fibrillation (nr_03 = 'yes'), it is more likely that they may have chronic heart failure.
- If the patient does not have a history of paroxysms of atrial fibrillation (nr_03 = 'no'), it is less likely that they have chronic heart failure.

Based on this analysis, here is the dictionary with the possible values of feature nr_03 for each target class:

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

This dictionary indicates that for the target class "no" (indicating no chronic heart failure), the only possible value of feature nr_03 is "no". For the target class "yes" (indicating the presence of chronic heart failure), the only possible value of feature nr_03 is "yes".