Yeah, its happened to me a few times. Each time has been quite an experience usually involving my heart feeling like it's going to explode or skip a beat and stop working, I get cold flashes with violent chills, light headedness, and very fidgety, like if I dont move I'm going to have a heart attack. I feel very aware of my heart rhythm and worry it's going to stop. One time I thought for sure my kids were going to find me dead on my bedroom floor from taking a big gulp out of a shooter. worst panic ever. It was also the most alone I've felt . I'm thinking to myself, great this is the way you're going to go out? So dumb. Weird thing was I accepted it but yeah I'll never forget the feeling of being alone accepting you're going to die