This reminds me of something:
“He died of natural causes. His heart stopped when I shoved a knife into it.”
The point being that you can’t always get the full picture of someone’s cause of death if you just look at what caused the cessation of life. Because, after all, everyone who has ever died (and who ever will die in an organic body) died of cellular death (there is a Latin term for this, but I can’t think of it right now). Knowing that tells you nothing, however. You have to know why the person’s cells died. ‘Pneumonia’ is a more accurate cause, but it could also ignore a root cause. Like AIDS. Likewise, cardiac arrest is often the end result of cocaine abuse. Yes, cardiac arrest killed the person, but the cardiac arrest was caused by a $1000-a-day cocaine habit.
On the other hand, it is possible to get too far into root causes. For example, cocaine abuse could be caused by emotional disturbances, which could be caused by a bad home life. So, do we say that a bad home life killed the guy on the slab? No, we say cardiac arrest is the immediate cause of death, the cardiac arrest being caused by cocaine abuse.
Okay, the root point of this is that while the immediate cause of death might be on file, it could tell you next to nothing about what actually caused his death.