A childhood belief about people

My grandpa died of a heart attack shortly before my birth. For years, I thought his heart was attacked by something, like tiny ants who entered his body with swords and such and attacked his heart and killed him. No matter who had this heart attack, that same army of ants would attack people's hearts, so my little head believed. Fortunately, I finally asked Dad, and he told me what happened, in little kid terms.