```json
{
	"no": ["no"],  
	"yes": ["yes"]
}
```
Since the feature "n_r_ecg_p_06" represents the persistent form of atrial fibrillation on the electrocardiogram (ECG) at the time of admission to the hospital, there are only two possible categories: "no" - indicating the absence of persistent atrial fibrillation, and "yes" - indicating the presence of persistent atrial fibrillation.
Therefore, the possible values for the feature "n_r_ecg_p_06" for the target class "no" are ["no"], and for the target class "yes" are ["yes"].