```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```
Since the feature "ritm_ecg_p_02" is categorical with two possible values, "no" and "yes", the relationship between this feature and the occurrence of chronic heart failure can be determined directly. If the value of "ritm_ecg_p_02" is "no", it indicates that the patient did not have atrial fibrillation at the time of admission to the hospital, and therefore, chronic heart failure may not be present. If the value is "yes", it indicates that the patient did have atrial fibrillation, and there may be a higher likelihood of chronic heart failure.