HRT/Testosterone and Heart Disease

Upon reading many clinical research publications I have noticed that some medical professionals believe there may be a link between heart disease and low testosterone.  One study reported that a good portion of CAD people suffer from hypogonadism as well.

I have a few questions.  Does low testosterone lead to heart disease or does heart disease cause low testosterone levels (which is the chicken and the egg so to speak)?  Are their any dangers for a person with heart disease partaking in hormone replacement therapy?  I am curious what you guys think about heart disease and its relationship to testosterone (or lack there-of).  Also, would HRT therapy for an individual with Bicuspid Aortic Valve disease have any issues?

Thanks!