Imitrex and mitral valve

Question...I have had migraines for most of my life, the first one I remember was when I was 7. I cannot stomach narcotic pain relievers and was thrilled when Imitrex came out. I took it for years. The only side effects I had were a warm rush, like an alcohol buzz, and sleepiness. Then, 5 years ago I was diagnosed with severe mitral regurgitation. My doctor took me off Imitrex right away and switched me to Maxalt, which I also love. It works great. I had open heart in 2001 to fix the mitral valve, then early in 2005 discovered I have tricuspid regurgitation. No surgery as of yet, thank God. I am on disability for the first heart problem and medicare and medical assistance will no longer cover the Maxalt, only the Imitrex. I took one the other day and almost had to go to the ER. I could barely move, breathe, or speak. Thankfully, after an hour or so, the symptoms subsided. But it really scared me. Now my doctor is giving me all the samples he can of Maxalt that they get in the office.
I am wondering if there is a connection between vavular disease and Imitrex? Has anyone had any of these problems?