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

Based on the feature description, the feature "MP_TP_POST" indicates whether the patient had paroxysms of atrial fibrillation at the time of admission to the intensive care unit or prehospital stage. 
To analyze the relationship between this feature and the presence of chronic heart failure, we can consider the following scenarios:
- If the feature value is "no", it suggests that the patient did not have paroxysms of atrial fibrillation.
- If the feature value is "yes", it suggests that the patient had paroxysms of atrial fibrillation.

Given that the task is to determine whether the patient has chronic heart failure, there is no specific information available on how the presence of paroxysms of atrial fibrillation relates to chronic heart failure. Therefore, it is difficult to predict the relationship between the feature and the task accurately.

However, to create the dictionary, we can assume that the presence of paroxysms of atrial fibrillation might be associated with chronic heart failure. Hence, for the target class "no" (indicating no chronic heart failure), the feature value "no" is a possible value for MP_TP_POST. For the target class "yes" (indicating chronic heart failure), both "no" and "yes" can be possible values for MP_TP_POST.

Please note that this assumption is based on general knowledge and there might be other factors involved in determining the relationship between MP_TP_POST and chronic heart failure for this specific dataset.