Based on prior knowledge, a first-degree AV block on ECG at the time of admission to the hospital can be an indication of chronic heart failure. 

To analyze the relationship between the feature, n_p_ecg_p_03, and the task of determining whether the myocardial infarction complications data of this patient shows chronic heart failure, we can examine the distribution of the feature's categories for each target class.

Here is a dictionary describing the possible values of the feature n_p_ecg_p_03 for each target class:

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

In this case, there are only two possible values for the feature, "no" and "yes". The "no" category indicates that the patient does not have a first-degree AV block on ECG at the time of admission to the hospital, while the "yes" category indicates that the patient does have a first-degree AV block on ECG at the time of admission to the hospital.

Please note that the dictionary includes all possible values for each target class, as specified in the given feature description.