Based on my prior knowledge, the presence of Complete RBBB (Right Bundle Branch Block) on an ECG at the time of admission to the hospital is not specific to chronic heart failure. RBBB can occur due to various reasons and may or may not be related to chronic heart failure.

However, to generate the dictionary as requested, I will assume that there might be some relationship between the feature and the target variable. Here is the dictionary:

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

Please note that in this dictionary, I have included all possible values of the feature "n_p_ecg_p_12" for the target classes "no" and "yes". Since the feature itself does not directly indicate chronic heart failure, the list for the "no" target class only contains the value "no". The list for the "yes" target class includes both "no" and "yes" to cover all possibilities.

Please keep in mind that the actual relationship between this feature and chronic heart failure would require further analysis and possibly additional features to make a more accurate prediction.