Based on the feature description and task, the goal is to analyze whether the presence of paroxysms of atrial fibrillation in the patient's medical history (feature: nr_03) is related to the occurrence of chronic heart failure (target variable).

To determine this relationship, we can analyze the distribution of nr_03 values for each target class (yes or no) and check if there are any noticeable patterns or differences.

Here is the dictionary with the analysis results:

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

Explanation:

For the target class "no" (no chronic heart failure):
- The possible value of feature nr_03 is "no". This indicates that patients without chronic heart failure do not have paroxysms of atrial fibrillation in their medical history.

For the target class "yes" (chronic heart failure):
- The possible value of feature nr_03 is "yes". This suggests that patients with chronic heart failure have paroxysms of atrial fibrillation in their medical history.

Please note that since the feature description only includes two possible categories, "no" and "yes", we do not have any hard-to-predict values for nr_03 in this case. As a result, the dictionary only includes the possible values observed for each target class.