Based on prior knowledge, the feature "endocr_02" represents obesity in the patient's medical history. To determine if there is a relationship between "endocr_02" and the presence of chronic heart failure in the myocardial infarction complications data, we need to analyze the distribution of "endocr_02" values for each target class.

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

In this case, since "endocr_02" is a binary categorical variable with only "no" and "yes" as possible values, we can directly map them to the target classes "no" and "yes" respectively. There is no need for further analysis as the relationship is clear-cut.