My cat has tested positive for heartworm, what are the next steps?

X-rays, monitoring, and bracing owners that this cat may go into a fatal crisis when this heartworm dies (they live about two years). There's not a whole lot you can do to prevent that. Despite the best of efforts, those cats die. Sometimes specialists can surgically/manually remove heartworm, but it’s costly. How often it's done, I'm not sure. It's probably a pretty risky procedure, too, I would think.