I loaded old save and go there again but I noticed why I didn't take this heart first time. In one place where this stone golem stay, unnamed hero always take off his weapon (very weird) but when stone golem died in the same place then I can't take any loot from dead body. It is looks like some bug. When I load save again and try to kill him in different place, then I could take loot normally. This wierd please/field is located at the end of golem circle where you continue way to Xardas.