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

Based on the feature description and the task, it appears that the feature `zab_leg_02` represents the presence or absence of chronic bronchitis in the patient's medical history. To determine if this feature is related to the presence of chronic heart failure, we need to analyze the relationship between `zab_leg_02` and the target variable.

Given the limited information provided, it is difficult to predict how this specific feature might be related to the target variable. However, we can assume that if a patient has a history of chronic bronchitis (value "yes" for `zab_leg_02`), it might suggest a higher risk of chronic heart failure. On the other hand, if a patient does not have a history of chronic bronchitis (value "no" for `zab_leg_02`), it might indicate a lower risk of chronic heart failure. 

Please note that these assumptions are based on general knowledge and prior experience, and a thorough statistical analysis would be required to confirm these relationships.