I'm a retired radiologist with a huge experience performing coronary CT angiography (CCTA). This is an amazingly accurate exam, superior to cardiac catheterization and stress tests. Radiation dose from this exam has been dramatically reduced in recent years,

Having seen thousands of these studies I can state that many people have severe coronary artery disease at young ages (in their thirties). They are at risk for sudden death. Often they come in for the exam because a parent or sibling died prematurely either recently or at the same age as they are now.

What's interesting, in my experience, is that very often when siblings get the exam, the one with obvious risk factors such as obesity, smoking, diabetes, etc has a normal exam result and the sib with no risk factors (other than maybe sharing a bad family history) has severe disease.

Read about CCTA http://goo.gl/o1RvD5