Why testestrone replacement has risk for heart attack and stroke?

Testosterone: At the present time, the FDA has NOT concluded that there is an increased risk for heart attack and stroke if prescribed properly. Testosterone is a hormone essential to the development of male growth and masculine characteristics. Testosterone products are FDA-approved only for use in men who lack or have low testosterone levels in conjunction with an associated medical condition. http://www.fda.gov/Drugs/DrugSafety/ucm383904.htm