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

Based on the feature description and the task, it seems that the target variable is whether the patient shows chronic heart failure or not. The feature, "B_BLOK_S_n", represents the use of beta-blockers in the intensive care unit (ICU) and is a categorical variable with two categories: "no" and "yes". 

From the provided information, it is unclear how the use of beta-blockers in the ICU is related to chronic heart failure. Without any prior knowledge, it is difficult to predict if one category of the feature is more likely to be associated with chronic heart failure compared to the other.

Considering this, it is not possible to analyze the relationship between the feature and the target variable using only the given information. The dictionary provided includes the possible values for both target classes ("no" and "yes"), but it is not possible to further determine their relationship without additional information or analysis.