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

Based on the feature "B_BLOK_S_n", there are two possible values: "no" and "yes". 

If the patient has chronic heart failure, the value of "B_BLOK_S_n" would be "yes". Hence, the only possible value for the feature "B_BLOK_S_n" in the case of chronic heart failure is "yes".

If the patient does not have chronic heart failure, the value of "B_BLOK_S_n" would be "no". Therefore, the only possible value for the feature "B_BLOK_S_n" in the case of no chronic heart failure is "no".

Therefore, the dictionary will have "no" mapped to ["no"] and "yes" mapped to ["yes"].