After conducting a thorough analysis of the relationship between the feature "STENOK_AN" and the task of determining whether the patient has chronic heart failure, the following observations can be made:

- Patients who have experienced exertional angina pectoris in the anamnesis "never" are less likely to have chronic heart failure.
- It is challenging to predict whether patients who have experienced exertional angina pectoris in the anamnesis "during the last year" or "more than 5 years ago" will have chronic heart failure.

Based on this analysis, the dictionary representing the relationship between the feature and the task can be created as follows:

```json
{
	"no": ["never"],
	"yes": ["during the last year", "more than 5 years ago"]
}
```

Please note that the dictionary only includes the values of the feature that are more indicative of the target class, and not all possible values.