And then he was dead.
( Is it a good thing to know that you are going to suddenly die? )
I think they are saying that sudden cardiac death wasn't so sudden. The signs were there if the people knew how to read them. If there is a family history, these symptoms should never be ignored.
The point is that if there are warning signs, people need to pay attention, and take their medicines and go to emergency, when these symptoms appear and NOT wait until they "suddenly" die.
For a long time, it was thought that there are no warning signs. A couple of hours is enough time to allow people to get to the emergency room and/or call paramedics, and hopefully get to the hospital and save their lives.