An implantable medical device and method are provided for assessing autonomic
tone and risk factors associated with arrhythmias and, based on this assessment,
an early recurrence of ventricular tachycardia or ventricular fibrillation is predicted.
Specifically, changes in R-R interval, heart rate variability, patient activity,
and myocardial ischemia are measured prior to and after a detected an arrhythmia
episode. A recurrence score is calculated as a weighted sum of measured parameters
and compared to a prediction criterion. The prediction criterion may be a preset
threshold score or an individualized episode template based on previously calculated
recurrence scores associated with recurring episodes. Stored parameters and episode-related
data may be downloaded for offline analyses for optimizing prediction criteria
and monitoring patient status.
