Based on prior knowledge, I will analyze the relationship between the feature "IBS_POST" and the task of determining whether the myocardial infarction complications data of this patient show chronic heart failure or not.

Since the feature "IBS_POST" represents the occurrence of coronary heart disease in recent weeks before admission to the hospital, it is possible that patients with certain categories of "IBS_POST" may have a higher likelihood of developing chronic heart failure. 

To analyze the relationship, I will examine the distribution of "IBS_POST" categories among patients with and without chronic heart failure.

Here is the dictionary with the specific details:

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

In this case, patients without chronic heart failure are likely to have "IBS_POST" categories of "there was no СHD" and "exertional angina pectoris". On the other hand, patients with chronic heart failure are likely to have "IBS_POST" category of "unstable angina pectoris".

Please note that this analysis is based on prior knowledge and might not capture all potential relationships between the feature and target accurately.