```json
{
	"no": ["no"],  
	"yes": ["yes"]
}
```
Based on the feature description, there are two possible values for the FIB_G_POST feature: "no" and "yes". The feature indicates whether the patient had ventricular fibrillation at the time of admission to the intensive care unit. 

To determine if the patient is showing chronic heart failure, we would need additional information related to chronic heart failure, as the FIB_G_POST feature alone does not provide direct information about chronic heart failure.