Discrimination between Demand and Supply Ischemia Episodes in Holter Recordings

ST segment changes provide a sensitive marker in the diagnosis of myocardial ischemia in Holter recordings. However not only the mechanisms of ischemia result in ST segment deviation but also heart rate related events. The very similar signature of ST modifications in ischemia and heart rate related events have driven us to look for other ECG indexes allowing to discriminate between them. Heart rate-based indexes, correlation between the absolute ST segment deviation and heart rate series, the interval between T apex and T end and changes in the upward/downward slopes of the QRS complex have been shown as significant discriminant parameters, getting a sensitivity for the ischemic events SE = 82 2%, specificity SP = 88.4%, positive predictivity value +PV = 87.6% and negative predictivity value -PV = 83 2% in ST events of the long term ST database.