Based on my prior knowledge, patients with chronic heart failure may experience exertional angina pectoris as one of the symptoms. Therefore, the feature "STENOK_AN" may be related to the presence of chronic heart failure.

To analyze the relationship between the feature "STENOK_AN" and the presence of chronic heart failure, we can examine the distribution of the feature values for each target class.

Analyzing the data, we can create the following dictionary:

```json
{
    "no": ["never"],
    "yes": [
        "during the last year",
        "more than 5 years ago",
        "4-5 years ago",
        "one year ago",
        "two years ago",
        "three years ago"
    ]
}
```

Based on the preliminary analysis, patients without chronic heart failure (target class "no") only have a value of "never" for the feature "STENOK_AN". On the other hand, patients with chronic heart failure (target class "yes") have a range of values for the feature "STENOK_AN".

Please note that the chosen values depend on the available data and may vary in different datasets.