Based on prior knowledge, the use of calcium channel blockers (ANT_CA_S_n) can potentially have an impact on the development of chronic heart failure in patients with myocardial infarction complications.

To analyze the relationship between the feature ANT_CA_S_n and the task of determining if the patient shows chronic heart failure, we can look at the possible values of ANT_CA_S_n for each target class (yes or no).

Here's a dictionary representing the analysis:

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

In this analysis, there is only one possible value for each target class. For the target class "no" (no chronic heart failure), the only value of ANT_CA_S_n is "no". Similarly, for the target class "yes" (chronic heart failure), the only value of ANT_CA_S_n is "yes".