Patent ID: 7899531

Claim:
A method for use in an implantable medical device implanted within a patient, said method comprising: training the device to distinguish between sleep time atrial fibrillation and non-sleep time atrial fibrillation by: acquiring patient activity information using the device, wherein the patient activity information comprises vagal nerve activity information, information sufficient to indicate if a patient is asleep and information sufficient to indicate if a patient is in an activity state other than asleep; acquiring patient electrocardiogram information using the device, wherein the information is sufficient to indicate if the patient is experiencing atrial fibrillation; upon detection of an episode of atrial fibrillation, associating the acquired vagal nerve activity information with sleep time atrial fibrillation if the acquired patient activity information indicates that the patient is asleep at the time of atrial fibrillation detection, or associating the acquired vagal nerve activity information with non-sleep time atrial fibrillation if the acquired patient activity indicates that the patient is in an activity state other than asleep at the time of atrial fibrillation detection; subsequent to the training, upon occurrence of sensed vagal nerve activity associated with sleep time atrial fibrillation, selecting an anti-atrial fibrillation therapy and calling for delivery of the selected anti-atrial fibrillation therapy to prevent and/or terminate atrial fibrillation classified as sleep time atrial fibrillation; and subsequent to the training, upon occurrence of sensed vagal nerve activity associated with non-sleep time atrial fibrillation, selecting an anti-atrial fibrillation therapy and calling for delivery of the selected anti-atrial fibrillation therapy to prevent and/or terminate atrial fibrillation classified as non-sleep time atrial fibrillation.