YOU SAID:
My grandfather died due to heart disease.
INTO JAPANESE
私の祖父は心臓病で亡くなりました。
BACK INTO ENGLISH
My grandfather died of heart disease.
INTO JAPANESE
私の祖父は心臓病で亡くなりました。
BACK INTO ENGLISH
My grandfather died of heart disease.
That didn't even make that much sense in English.