There's no reason why all of the tales of Curzon's death can't be true. They will all fit. It probably went like this:
- Curzon and Arandis do some serious knockin' boots. It's strong enough to cause Curzon to have a heart attack.
- However the attack isn't immediately fatal. Curzon is taken to a hospital where the doctors try to treat him (Curzon yelling all the way) but it doesn't work, they know he's going to die.
- Thus the doctors leave and Curzon calms down enough to let the symbiont be transplanted from him to Jadzia.