```json
{
    "no": ["no"],
    "yes": ["yes"]
}
```
Based on the given feature and task, the n_r_ecg_p_05 feature is a categorical variable with two possible categories: "no" and "yes". 

In this analysis, the feature is suggestive of the presence of paroxysms of atrial fibrillation on the ECG at the time of admission to the hospital. 

For the target class "no", the only possible value for n_r_ecg_p_05 is "no". This means that when there are no complications of myocardial infarction, chronic heart failure is not observed.

For the target class "yes", the only possible value for n_r_ecg_p_05 is "yes". This means that when there are complications of myocardial infarction, chronic heart failure is observed.

Therefore, the dictionary representing the relationship between the feature n_r_ecg_p_05 and the target variable (chronic heart failure) can be represented as shown above.