To calculate something like "60% heart failure chance" right after birth doesn't seem to possible to me. Too much depends on environment, bad luck and habits. That "60%" would have a deviation of 50 or something and be nearly useless. That said the basic idea will certainly come true. Some things are at least partly genetic and medicine will probably be able to test this at some point. In vitro fertilization is probably where it's used first.
You really nailed the entire movies premise with this it seems. The main character isn't "suited" for his desire, but pursues it anyway, and overcomes his genetic labeling.
Gattaca is a place that exists because your environment, luck, and habits are all controlled to some extent. Imagine a rat in a cage - stimulated to exercise, rest, learn, eat, exactly what you want, when you want. You can eliminate nearly all of the variables if you wish. Think of Gattaca in this way and Ethan Hawks character is a "Neo". Great movie!
