Based on prior knowledge, we can analyze the relationship between the feature "ANT_CA_S_n" (Use of calcium channel blockers in the ICU) and the task of determining if the patient has chronic heart failure.

Since the feature is categorical with two possible categories ('yes' and 'no'), we can examine how each category is related to the presence or absence of chronic heart failure:

1. If the value of "ANT_CA_S_n" is 'yes', it means that the patient used calcium channel blockers in the ICU.
    - If the patient has chronic heart failure, it is possible that the use of calcium channel blockers in the ICU is a treatment for managing the condition. Therefore, some patients with chronic heart failure may have the value 'yes' for this feature.
    - If the patient does not have chronic heart failure, it is less likely that the use of calcium channel blockers in the ICU is related to the condition. Therefore, the rate of patients without chronic heart failure having the value 'yes' for this feature might be lower.

2. If the value of "ANT_CA_S_n" is 'no', it means that the patient did not use calcium channel blockers in the ICU.
    - The absence of calcium channel blockers may be unrelated to chronic heart failure.
    - Therefore, the rate of patients with and without chronic heart failure having the value 'no' for this feature might not vary significantly.

Based on this analysis, let's create the dictionary:

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

The above dictionary suggests that patients with both chronic heart failure and without chronic heart failure can have the value 'yes' for the feature "ANT_CA_S_n".