LESSONS LEARNED FROM DATA LOGGING IN A MULTICENTER CLINICAL-TRIAL USING A LATE-GENERATION IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR

Objectives. This study examined patterns of implantable cardioverter-d efibrillator use as documented by data logging. Background. Implantabl e cardioverter defibrillators are accepted therapy for malignant ventr icular tachyarrhythmias; however, relatively little is known about the ir patterns of use. Incorporation of data-storage capacities into thes e devices provides insight into long-term defibrillator function. Meth ods. Stored data-logging information was retrieved from 401 implanted cardioverter-defibrillators in 393 patients over an average of 303 day s of follow up. Results. A total of 91,443 detections were recorded in 299 patients. One hundred-six patients (26%) had detections due to su praventricular tachycardias, electrical noise or other causes, resulti ng in inappropriate therapy delivery to 92 patients (23%). Two hundred eighty-one patients recorded 66,276 episodes of ventricular tachycard ia or ventricular fibrillation. Of these, 74.4% episodes terminated sp ontaneously without any delivered therapy, 22.1% terminated after anti tachycardia pacing, and 1.7% terminated after shock therapy. Antitachy cardia pacing was activated without formal testing in 47% of all patie nts receiving this therapy and was successful in 96% of all episodes r eceiving this therapy. Acceleration of tachycardia to shock therapy oc curred in 1.3% of all episodes and in 30.5% of patients receiving anti tachycardia pacing. Thirty four patients (8.7%) died during follow up. Mortality was associated with patient age, heart failure functional c lass at implantation and frequency of shocks received during follow-up (all p less than or equal to 0.05). Conclusions. Most ventricular tac hyarrhythmia detections by this noncommitted implantable cardioverter defibrillator resolve spontaneously, whereas the majority receiving th erapy can be treated with antitachycardia pacing. Mortality after impl antable cardioverter-defibrillator implantation is associated with age , heart failure class and frequency of shocks received during follow-u p. Data-logging capabilities provide valuable insights into the patter ns of defibrillator use.