I find that the genetic component is very difficult to evaluate in that there are lots of reasons for people to have heart attacks at younger ages in previous generations.
The important things for your husband are:
1)does he have concerning symptoms (chest pain, shortness of breath)
2)is he overweight?, have high blood pressure?
3)does he exercise?, smoke?
4)he should have a fasting lipid profile
All of these will help figure out his cardiac risk and the need (or not) for a stress test.
Thank you again for your time. I guess my real worry is that my husband's great-grandfather, grandfather, and dad were all in good health, non-smokers, and not overweight when this happened to them.
Thanks again! I will make sure to start with the fasting lipid profile....