```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```
Based on the given feature description and task, it appears that the feature "endocr_03" represents whether the patient has a history of Thyrotoxicosis. 

Since we are trying to determine whether the patient has chronic heart failure or not based on myocardial infarction complications data, it is difficult to predict the relationship between the feature "endocr_03" and the target variable.

In this case, there are two possible values for the feature "endocr_03": "no" and "yes". 

However, since we don't have any prior knowledge about the relationship between "endocr_03" and chronic heart failure, we cannot make any specific statements about the possible values of the feature for the target classes. Therefore, the dictionary contains only the possible values of the feature without any additional details.