```json
{
    "no": ["no"],
    "yes": ["yes"]
}
```
Based on the given feature description and task, it appears that the only possible value for the feature `ritm_ecg_p_04` is either "no" or "yes". Therefore, for the target class "no", the possible values of the feature would be ["no"], and for the target class "yes", the possible values of the feature would be ["yes"].