CuzzA
Wetwork for Hire
It's a possibility though in that article it does say half of people who experience it have symptoms for a few minutes. I also recall reading a different article that nearly half of cardiac deaths happen when a person is sleeping so that could skew data.Heart Disease and Sudden Cardiac Death
From that article in Web MD:
Sudden cardiac death (SCD) is a sudden, unexpected death caused by a change in heart rhythm (sudden cardiac arrest). It is the largest cause of natural death in the U.S., causing about 325,000 adult deaths in the U.S. each year. SCD is responsible for half of all heart disease deaths.
Also, they list the risk factors. We don't know his health history, but he appears in photos to be fit. I can't say I know of a case personally where a healthy person has died in their thirties from a heart attack or cardiac arrest. I know it has happened, but I would assume if you don't have the risk factors the incidence is extremely low for a 37 year old. I agree it would certainly explain near instant unconsciousness.
Sadly, we will never know what actually happened. The only thing we can truly eliminate would be the condition of his breathing gas.
If there's anything to learn here though, I think it's important to ensure you are truly neutral on your stops. I recall when I first started diving I thought I was neutral on my safety stop, but in reality I was gently finning up. Now when I'm vertical (proper technique when fishing) I gently scissor my fins in and out to maintain balance and occupy my brain's impulse to kick.