Based on prior knowledge, chronic pneumonia in the anamnesis (feature zab_leg_04) may be related to the occurrence of chronic heart failure in a patient. To analyze the relationship between this feature and the task, we can examine the frequency distribution of values for the feature in each target class.

Here is the dictionary with the possible values of feature zab_leg_04 for each target class:

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

Based on the given feature description, the only possible values for feature zab_leg_04 are "no" and "yes".