I had this, I was in very good shape (15s~ for 100m sprint sets for fun) and nearly died of grief. If you're old and your system is frail, I can easily see how your emotional state could disrupt it.
ps: to add some details, here are a few hypothesis (AFAIcan understand)
- tako tsubo syndrom, emotional shock => hormone cascade => myocard deformation to the point of uselesness
- arteries constrictions, nearly all your arteries (even micro capillaries) have tiny valve-rings, since fear can induce vasoconstriction to ensure high blood supply, I think high anxiety can force your system in that state for prolonged amount of time which will lead to blood flow disruption (tiny clots, mild hypoxia) and derail organs on the way.
These bonds root deep in us.