```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```
Based on the given feature description, the feature "n_p_ecg_p_12" is a categorical variable with two possible values: "no" and "yes". 

To analyze the relationship between this feature and the task of determining if the patient has chronic heart failure, we can consider the medical significance of Complete RBBB (Right Bundle Branch Block) on ECG.

ECG (Electrocardiogram) is a test that measures the electrical activity of the heart. Complete RBBB refers to a delay or blockage of the electrical impulse in the right bundle branch of the heart's electrical conduction system. This can indicate various cardiac conditions.

A patient with Complete RBBB on ECG at the time of admission might have a higher likelihood of chronic heart failure. However, without further information or additional features, it is difficult to predict the presence of chronic heart failure with certainty based solely on this feature.

As the feature "n_p_ecg_p_12" only has two possible values, "no" and "yes", we can create a dictionary with these values as the possible values for each target class:
```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```
Note: This assumes that each target class has at least one corresponding value of the feature.