Based on the given feature "n_r_ecg_p_04" and the task of determining if the patient has chronic heart failure, we need to analyze the relationship between the feature and the target variable. 

It is not explicitly mentioned in the feature description how "Frequent premature ventricular contractions on ECG at the time of admission to hospital" is related to chronic heart failure. However, based on prior knowledge, frequent premature ventricular contractions (PVCs) can be a sign of heart rhythm abnormalities and can be associated with various cardiac conditions, including chronic heart failure. 

To analyze the relationship between the feature and the target variable, we can consider the following:

1. If the value of the feature "n_r_ecg_p_04" is "yes" (indicating the presence of frequent PVCs on ECG at the time of admission), it may suggest a higher likelihood of chronic heart failure.
2. If the value of the feature "n_r_ecg_p_04" is "no" (indicating the absence of frequent PVCs on ECG at the time of admission), it may suggest a lower likelihood of chronic heart failure.

However, without additional information or data, it is not possible to definitively determine the relationship between the feature and the presence of chronic heart failure. The feature alone cannot provide a conclusive answer to the task.

Based on this analysis, we can generate the following dictionary:

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

Note: In this case, since the feature only has two possible categorical values ("yes" or "no"), we include them in the dictionary for each target class.