It can be acquired by searching the body of a dead Sasquatch.
Sometimes, the player will not be given the loot prompt after killing a sasquatch, thus not being able to loot Sasquatch heart. It is said that reloading a save may fix this.
|Hey there, cowboy. It looks like this little ol' article is a bit puny.|
I reckon you could impress me by adding to it. Don't be shy now.
If you're logged in, it'll help you earn them fancy achievements, too.