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

Based on the given feature "Premature atrial contractions in the anamnesis" (nr_01) and the task of determining whether the patient's myocardial infarction complications data show chronic heart failure, the feature values can be divided into two categories: "no" and "yes". 

If the patient's myocardial infarction complications data does not show chronic heart failure, the value of nr_01 would be "no". On the other hand, if the patient's myocardial infarction complications data does show chronic heart failure, the value of nr_01 would be "yes".

Therefore, there are two possible values for the feature nr_01: "no" and "yes".