```json
{
    "no": ["no"],
    "yes": ["yes"]
}
```
Based on the given feature "ritm_ecg_p_04" and the task of determining if the patient shows chronic heart failure, it appears that the feature directly corresponds to the target class. The feature has two categories: "no" and "yes", which represent whether or not the patient has atrial ECG rhythm at the time of admission to the hospital. If the patient has atrial rhythm ("yes"), it implies chronic heart failure. If the patient does not have atrial rhythm ("no"), it implies the absence of chronic heart failure. Therefore, the values of the feature "ritm_ecg_p_04" directly represent whether or not the patient shows chronic heart failure.