Hi, DJ,
Yes, certain things associated with heart attacks, such as cholesterol levels, produced by the body, are hereditary.
http://www.netdoctor.co.uk/ate/heart...od/203470.html
There are many liinks on the web about it. The above is just one.
My other Dad passed away at 56 with heart disease, but I'm 64 now. His parents had no history of the disease.
I do wish your uncle well, and a swift recovery, from whatever it might be. Running an EKG, checking the heart beats, is normal for chest pain, as well as other tests.