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

Based on the given feature description and task, the feature "n_p_ecg_p_12" represents the presence or absence of complete right bundle branch block (RBBB) on an electrocardiogram (ECG) at the time of admission to the hospital. 

To determine if the myocardial infarction complications data of this patient show chronic heart failure, we need to examine the relationship between the feature "n_p_ecg_p_12" and the target variable. However, the given feature description does not provide enough information to establish a clear relationship. Since the feature is categorical with only two possible values: "no" and "yes", we can assume that "yes" represents the presence of complete RBBB on the ECG, while "no" indicates its absence.

Hence, the dictionary representation of the feature "n_p_ecg_p_12" for the target class is:

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

Note: It is important to recognize that without further information or additional features, it might not be possible to accurately predict chronic heart failure based solely on the presence or absence of complete RBBB on the ECG.