Based on my prior knowledge, AST (Aspartate Aminotransferase) is an enzyme found in high levels in the liver, heart, and muscle cells. Elevated levels of AST in the blood could indicate liver disease, muscle damage, or heart attack.

To determine the appropriate ranges of values for AST_BLOOD, I would consider the normal range of AST levels in the blood. On average, the normal range for AST in adult males is 10 to 40 units per liter (U/L), and for adult females, it is 9 to 32 U/L. However, it's important to note that these ranges can vary slightly depending on the laboratory and individual factors.

To analyze the relationship between AST_BLOOD and the presence of chronic heart failure in myocardial infarction complications, I would compare the AST_BLOOD values for patients with chronic heart failure (target class 'yes') and those without chronic heart failure (target class 'no').

Here's a dictionary representing the relationship between AST_BLOOD and the target class:

```json
{
	"no": [20.5, 18.2, 15.9, 22.1, 13.7], 
	"yes": [30.4, 28.6, 25.3, 35.9, 32.2]
}
```

In this case, I have included 5 typical AST_BLOOD values for both the 'no' and 'yes' target classes. The values provided are arbitrary and for demonstration purposes only. The actual values would depend on the specific data and analysis conducted.