Can't find it, if it exists
As far as I'm aware he had serious heart complications, not sure if that was fully aware of before he had fights with Dada 5000 or Shamrock. Problem was, he wasn't exactly training hard enough for fights, it's an accepted likelihood that he was doping throughout his MMA career too and was laid back in training which I doubt helped the condition he was in and would later expand into him needing a heart transplant.
It's worth noting Dada 5000 essentially died after the fight and had to be revived.