Based on prior knowledge, we can analyze the relationship between the feature "GEPAR_S_n" and the presence of chronic heart failure in myocardial infarction complications data.

In order to determine if chronic heart failure is present, we need to analyze the relationship between the use of anticoagulants in the ICU (GEPAR_S_n) and the presence or absence of chronic heart failure.

To do this, we can examine the distribution of the "GEPAR_S_n" feature for both the "yes" and "no" classes of chronic heart failure. By observing the possible values of the feature for each class, we can determine if there is any discernible pattern or relationship.

Here is the dictionary containing the possible values of the "GEPAR_S_n" feature for each class:

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

In this case, for the "no" class (patients without chronic heart failure), the only possible value of the "GEPAR_S_n" feature is "yes". This implies that patients who do not have chronic heart failure are likely to be using anticoagulants in the ICU.

For the "yes" class (patients with chronic heart failure), both "yes" and "no" values of the "GEPAR_S_n" feature are possible. This means that patients with chronic heart failure may or may not be using anticoagulants in the ICU.

Please note that this analysis is based on prior knowledge and may not cover all possible scenarios. The provided dictionary should give a general understanding of the relationship between the feature and the target variable.