Based on your feature description "n_p_ecg_p_03" and the task of determining whether the patient has chronic heart failure, there are a few possibilities for the relationship between the feature and the target. Let's analyze it further:

1. If "n_p_ecg_p_03" is 'no':
   - It implies that there is no first-degree AV block on the patient's ECG at the time of admission.
   - This suggests that the patient may not have chronic heart failure.
   - However, this does not guarantee that the patient does not have chronic heart failure, as there could be other factors contributing to the condition.

2. If "n_p_ecg_p_03" is 'yes':
   - It indicates that the patient has a first-degree AV block on the ECG at the time of admission.
   - This could be indicative of a potential risk factor for chronic heart failure.
   - It is possible that patients with a first-degree AV block may be more likely to have chronic heart failure compared to those without.

Based on this analysis, we can create a dictionary with the following format:

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

The dictionary shows that the possible values for "n_p_ecg_p_03" for the target class 'no' is ["no"], indicating the absence of a first-degree AV block. Similarly, the possible values for the target class 'yes' is ["yes"], suggesting the presence of a first-degree AV block on the ECG.

Note that since the feature is categorical with only two possible values, there is no need to include other values in the dictionary as per your instructions.