I just called my vet and spoke with a tech. If you're referring to heart worm, which cats do get, Frontline also claims to kill mosquitoes which cause heartworm.

From what I know, Frontline and Advantage kill flea, flea eggs and ticks. Revolution kills fleas, flea eggs, ticks, mosquitoes and earmites.

Another way to see if the cats have worms is to look. Yeah, yeah, I know it's gross. I've looked in both poo and vomit. If you see what looks like string and it's moving, take him to the vet.