After analyzing the relationship between the feature "GEPAR_S_n" and the task of determining whether the patient shows chronic heart failure, we can create the following dictionary:

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

Explanation:
Based on prior knowledge, if the patient has chronic heart failure, it is unlikely that the patient will be using anticoagulants in the ICU ("GEPAR_S_n" value = "yes"). Therefore, the possible values for the feature "GEPAR_S_n" when the target class is "no" are ["yes"].

On the other hand, if the patient does not have chronic heart failure, it is likely that the patient might or might not be using anticoagulants in the ICU ("GEPAR_S_n" value can be either "yes" or "no"). Therefore, the possible values for the feature "GEPAR_S_n" when the target class is "yes" are ["no"].

Please note that this analysis is based on limited information and assumptions. It is always recommended to perform a comprehensive analysis using actual data before making any conclusive statements.