sudden death in Epilepsy

I had a gran mal seizure once and my heart stopped and I quit breathing. I was lucky enough to have a nurse close by who gave me CPR and got me going again and I happened to be just outside the VA hospital. All I knew is I woke up in ER and the doctor told me how lucky I was.

Sudden Unexpected Death in Epilepsy (SUDEP) is defined as the sudden, unexpected, witnessed or unwitnessed, non-traumatic and non-drowning death in a person with epilepsy, with or without evidence for a seizure, and excluding documented status epilepticus, in which postmortem examination does not reveal a structural or toxicological cause for death.
The major known risk factor established for SUDEP is the presence and frequency of generalized tonic-clonic seizures. People who have more than 3 generalized tonic-clonic seizures per year have a 15-fold increased risk of SUDEP. Nocturnal seizures may also increase risk, because of difficulty breathing sometimes present following a seizure. Unwitnessed nocturnal seizures and breathing difficulties that occur following a seizure can cause SUDEP.
More detail can be found in the link that I provided.

I never heard of it. What is it.