Based on prior knowledge, the use of beta-blockers (B_BLOK_S_n) in the ICU may have an impact on the development of chronic heart failure (CHF) as a complication of myocardial infarction (MI). Beta-blockers are commonly prescribed to patients with MI to improve survival and prevent the occurrence of CHF.

To analyze the relationship between the feature B_BLOK_S_n and the presence of CHF, we can examine the distribution of beta-blocker usage in patients with and without CHF.

Here's the analysis of the relationship between the feature B_BLOK_S_n and the presence of chronic heart failure (CHF):

- For patients with no chronic heart failure (target class: "no"): 
    - Possible values of feature B_BLOK_S_n: ["no", "yes"]
    
- For patients with chronic heart failure (target class: "yes"): 
    - Possible values of feature B_BLOK_S_n: ["no", "yes"]

Based on this analysis, we can create a dictionary with the following format:

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

Please note that the values "no" and "yes" in the dictionary are presented as strings in lists as per the requested format.