Experts now classify atrial fibrillation, also called A-fib, into the following types:
Paroxysmal: This means the heart goes into A-fib but within seven days returns to a normal rhythm. The person may or may not experience symptoms during this time.
Persistent: This refers to atrial fibrillation that's lasted at least seven days but not more than a year.
Permanent: This refers to atrial fibrillation that's lasted more than a year. It can also refer to atrial fibrillation of several months' duration if attempts to return the heart to the normal "sinus" rhythm have either failed or won't be pursued.
Atrial fibrillation tends to progress from paroxysmal to persistent and permanent, especially as people get older.