Based on prior knowledge, paroxysms of atrial fibrillation in the anamnesis (feature nr_03) could potentially be related to chronic heart failure. Atrial fibrillation is a type of arrhythmia that can contribute to the development of heart failure. Therefore, there might be a higher likelihood of chronic heart failure in patients who have experienced paroxysms of atrial fibrillation in their medical history.

Here is the dictionary containing the relationship between feature nr_03 and the task of determining if the patient has chronic heart failure:

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

Since the feature nr_03 only has two possible values, "no" and "yes", we can directly map these values to the target classes "no" and "yes" respectively.