Apparently, it’s good for your heart, too!
Amazing. Wonder if we’ll see a new round of Viagra commercials starring Bob Dole saying how good it is for your heart? (Followed by him starring in Pepsi spoofs of those a short time later.)
I had heard that the family of drugs Viagra is derived from are heart medication, and that they had kind of stumbled onto the, erm, utility of the drug by accident.
What Incubus said.
It was one of those quirky side effects of the heart meds in the first place that led medical researchers to add yet another to their list.
Shame many of the heart patients wouldn’t have been able to put the side-effect to good use for fear of exacerbating their coronary symptoms but. 
Riiiight. Next you’ll be trying to tell me that hair growth was only a side effect of Rogaine! Yes, I know they both were heart meds, but come on, when you hear someone talking about Viagra, do you really think, “I bet he’s taking it for his heart.”?