Based on my prior knowledge, I can analyze the relationship between the feature "IBS_POST" and the target variable of chronic heart failure. 

First, I will examine the possible values of the feature "IBS_POST":

- "there was no СHD": This category suggests that the patient did not have any coronary heart disease before admission to the hospital. It is possible that patients without coronary heart disease are less likely to develop chronic heart failure.
- "exertional angina pectoris": This category indicates the presence of exertional angina pectoris before admission. This condition involves chest pain or discomfort during physical activity or exertion, which may be a sign of underlying coronary heart disease. It is possible that patients with exertional angina pectoris have an increased risk of chronic heart failure.
- "unstable angina pectoris": This category suggests the presence of unstable angina pectoris before admission. Unstable angina pectoris is a severe form of angina that occurs even at rest or with minimal exertion. It is considered a medical emergency and is often associated with a higher risk of complications, including chronic heart failure. 

Based on this analysis, I can create a dictionary with the following format:

```json
{
	"no": ["there was no СHD"],
	"yes": ["exertional angina pectoris", "unstable angina pectoris"]
}
```