This one is going to be hard to determine the cause. The tackle itself didn’t appear to be related to anything that would cause a need for CPR. There was initial contact with Hamlin wrapping up the ball carrier and continued to rotate in a counter clockwise direction ball carrier in in a hug. There didn’t appear to be helmet contact and he landed with his head off the ground. Thoughts could lead to the possibility of a pregame injury.
A source tells FOX19 the Bills player, 24-year-old Damar Hamlin, has been intubated and is listed in critical condition at the University of Cincinnati Medical Center. Hamlin was given oxygen, placed on a stretcher, hooked up to an IV and eventually carried into an ambulance at the field. He required an automated external defibrillator on the field.
https://www.fox19.com/2023/01/03/bengals-bills-game-suspended-bills-damar-hamlin-critical-condition/
With Chuck Hughes, the autopsy revealed he had the heart of an 80-year old man.
Now I would hope these days, they do a much better job of screening players with potential heart conditions.