Based on prior knowledge, the ST_Slope feature can be related to the presence of heart disease in the following way:

- Up Slope: It is generally associated with a higher likelihood of heart disease. It indicates a rapid rise of ST segment during exercise, which may be indicative of insufficient blood flow to the heart.
- Flat Slope: It may be related to a lower likelihood of heart disease. It indicates that there is no significant ST segment elevation or depression during exercise, suggesting normal blood flow to the heart.
- Down Slope: It is also associated with a higher likelihood of heart disease. It indicates a slow decrease of the ST segment during exercise, which may be indicative of an abnormal flow of blood to the heart.

Based on this analysis, the dictionary can be generated as follows:

```json
{
	"no": ["Flat"],
	"yes": ["Up", "Down"]
}
```

Please note that with the given feature description, all possible ST_Slope values ('Up', 'Flat', 'Down') have been considered and only the relevant ones to predict the target class have been included in the dictionary.