Hi and welcome to HCM.
I am sorry about your husband. If you mean coronary arteries blockage then I dont know what is so mysterious to you . It seems like he had a fatal heart attack
. YOu cant know did he have pain before death occured,it can last for 1-2 minutes. It is not uncommon that people dont have angina pectoris
or any other chest pain
before heart attack. It depends from man to man. Wish you good health.