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

Based on the feature description, the feature "MP_TP_POST" represents whether the patient had paroxysms of atrial fibrillation at the time of admission to the intensive care unit or at a prehospital stage. 

To analyze the relationship between this feature and the task of determining chronic heart failure, we can look at whether the presence or absence of paroxysms of atrial fibrillation is associated with chronic heart failure.

The possible values of the feature are "no" and "yes". In the case that the patient does not have chronic heart failure, the only possible value of the feature would be "no". In the case that the patient does have chronic heart failure, the possible value of the feature can be either "no" or "yes".

Therefore, the dictionary representing the relationship between the feature "MP_TP_POST" and the task of determining chronic heart failure is as follows:
```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```
Please note that the dictionary only includes the values of "MP_TP_POST" that are relevant to the target class.