See chilly’s response. Uncorrected, respiratory arrest will ultimately lead to cardiac arrest. Then too a multitude of events could lead to cardiovascular collapse without any underlying cardiac disease.The only thing that leads me to think she may have had an underlying cardiac issue is that they said they defibrillated her - that's not as common. Defibrillation is more often associated with cardiac events.
Obviously, deepest sympathies to her family and friends, no matter what. Definitely a tragedy, no matter the cause.