Why shouldn't you use Sumatriptan if you have Raynaud's syndrome?

Added 8 Jun 2010:

I am doing fairly well at preventing most of my migraines, because I know what my triggers are. I have been having migraines since I was a young girl. I drink a lot of water (I always have a water bottle with me). I try to not eat/drink too much sugar in the afternoon (which is a trigger for me). I stay away from cheap hot dogs as much as possible. I take a multivitamin daily and sometimes extra magnesium, which also helps. However, I cannot usually prevent the monthly migraine that happens to me at the beginning of my cycle. My hormones must fluctuate a lot then and this pretty much always triggers a migraine. I tried a few preventative migraine medications, but I did not notice any change. Imitrex starts working within a half-hour and it's usually gone within an hour. However, it really sounds like I should look for another way to get rid of it. I do not like the side effects from the medicine and from the first reply I received (about the possibility of a heart attack) is very scary. I am only 29.