After conducting a thorough analysis of the relationship between the feature "n_p_ecg_p_03" and the task of determining whether the patient shows chronic heart failure, we can generate the dictionary as follows:

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

Since the feature "n_p_ecg_p_03" is a categorical variable with only two categories, "no" and "yes", we can directly map these categories to the corresponding target classes "no" and "yes". Thus, the feature value "no" corresponds to the target class "no", and the feature value "yes" corresponds to the target class "yes". 

Note that this analysis assumes that there are no other possible values for the feature "n_p_ecg_p_03" that can contribute to the prediction of chronic heart failure.