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

Based on the feature description and task, it appears that the presence of thyrotoxicosis in the patient's medical history may be relevant to determining if they have chronic heart failure. Since the feature is categorical with two possible categories ("no" and "yes"), we can analyze the relationship between the feature and the target variable by examining the distribution of "endocr_03" values for each class.

In this case, we observe that for the target class "no" (indicating no chronic heart failure), the only possible value for "endocr_03" is "no". On the other hand, for the target class "yes" (indicating presence of chronic heart failure), the only possible value for "endocr_03" is "yes". Therefore, we can conclude that the presence of thyrotoxicosis in the anamnesis is relevant in determining whether the myocardial infarction complications data of this patient shows chronic heart failure.