My dog died after epileptic seizure. What could be the cause of his death?

[princu_junior]

I had a labrador retriever and he had his first seizure when he was 3 years old. The doctor told us he had epilepsy and prescribed a medicine which has to be given 2 times a day. After that he still used to have the seizures and the frequency was usually 2-3 times in 3 months, and the seizures were usually cluster seizures. He had a cluster seizure 2 nights ago and died the next morning. He died aged 7.
Some other important things about him, i think he was not able to see certain things clearly, reason being, whenever i used to play catch with him he was never able to the catch the ball. He became inactive compared to the usual retriever, after the age of 2.
I went through different forums and it is stated everywhere that epilepsy does not kill dogs usually.
So i guess i just wanted to know wether epilepsy killed him or is there something I could have done like extra care or being more proactive towards his symptoms that could have saved him?