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

Based on the information provided, the feature "nr_01" represents the presence or absence of premature atrial contractions in the patient's medical history. To determine if it is indicative of chronic heart failure, we need to analyze the relationship between this feature and the target variable.

In this case, since the feature is categorical with two possible values ("no" and "yes"), we can examine the occurrence of these values for both the "no" and "yes" classes of the myocardial infarction complications data. 

After analyzing the data, we find that for the "no" class, the only value for feature "nr_01" is "no". Similarly, for the "yes" class, the only value for feature "nr_01" is "yes". Therefore, the presence of premature atrial contractions in the anamnesis is indicative of chronic heart failure in this particular dataset.