Sorry I don't have any dog-related info to share, but my sister and I both suffer from it -- mostly when we get clostrophobic. For me it's not a big deal at all. I haven't passed out for about two years, which is probably because I am rarely in crowded places.
My sister, however, takes regular rides in the ambulance because she seems to always faint on the Metro in the morning. She may have an underlying congenital heart defect (which her doctors were alerted to when her EKG results were consistently off after a VS episode last month). So for my sister the VS could save her life, without those EKGs she would still be walking around thinking it was just VS. (We are still waiting on number of test results to see what she will need.)
Sending good vibes to your Lahti. I know this is near impossible with dogs, but trying to prevent the vomiting (since that seems to be the trigger) would be what I would focus on, and maybe finding out if smelling salts can help dogs regain consciousness? You could carry them like an epi-pen for emergencies.
It's just a better life with dogs.