Based on my prior knowledge, arrhythmia in the anamnesis can be a potential risk factor for chronic heart failure. Therefore, it is likely that the presence of arrhythmia in the patient's history (nr_11 feature) is associated with chronic heart failure (target variable).

To analyze the relationship between feature nr_11 and the task of identifying chronic heart failure, we can examine the distribution of nr_11 values in the dataset for each class of the target variable.

Here is the dictionary with the details of the relationship between nr_11 and chronic heart failure:

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

Based on the available information, there is only one value for nr_11 in both target classes. For the target class "no," the only possible value is "no," indicating the absence of arrhythmia in the anamnesis. Similarly, for the target class "yes," the only possible value is "yes," indicating the presence of arrhythmia in the anamnesis.

Please note that since there is only one value in each target class, this analysis may not provide sufficient evidence to make a definitive conclusion regarding the relationship between nr_11 and chronic heart failure. Further data exploration and analysis would be beneficial to gain more insights.