No yearly vaccinations given here. I also do not use chemical flea, tick or heartworm preventative.
There are also natural cures for heartworm, including:Even I, who has a pet peeve against overmedication for heartworm, do it seasonally. It's very rare in my area, but better safe than sorry. I use a seasonal, minimal dosing schedule.
Even if all you do is annual testing without ever using preventative, if the dog comes up positive you'll have to put them on monthly medication for a full year (at least) to clear it up. So that sort of defeats the purpose of not wanting to overmedicate for it!