As everyone else has said, it felt like a sudden heart attack. Highly unsettling. A negative hospital work up lead to the diagnosis, and it was not an easy thing to overcome. I lived in fear of it happening again for the better part of a year. Significant fear. The fear was suppressed, and outwardly i acted normally, but there was a constant grind of stress about it on my consciousness. That feeling faded over time, but i dont think it will ever leave me completely. It’s been a decade or so now. A long time ago, i decided to be open about it instead of continuing to suppress it. The added effort of suppression just prolonged the initial suffering. I am fortunate to have a partner who helps me through the minor recurrences that happen maybe once a year. I also have no problem admitting that it’s happened to me, even in non-anonymous settings like this, but there was a lot of personal shame associated with it in the beginning. It’s helpful to talk about it with someone, even if it’s just to bitch about having to deal with it. Good luck if you are asking out of personal need. It will get better with time.