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

Based on prior knowledge, it can be concluded that if the ECG rhythm at the time of admission to the hospital is atrial fibrillation (ritm_ecg_p_02 = "yes"), it is likely to be associated with chronic heart failure. On the other hand, if the ECG rhythm is not atrial fibrillation (ritm_ecg_p_02 = "no"), it is less likely to be associated with chronic heart failure. Therefore, the possible values of feature ritm_ecg_p_02 for the target class "no" are ["no"], and for the target class "yes" are ["yes"].