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-defibrillator use as documented by data logging. Background. Implantable cardioverter defibrillators are accepted therapy for malignant ventricular tachyarrhythmias; however, relatively little is known about their patterns of use. Incorporation of data-storage capacities into these devices provides insight into long-term defibrillator function. Methods. Stored data-logging information was retrieved from 401 implanted cardioverter-defibrillators in 393 patients over an average of 303 days of follow up. Results. A total of 91,443 detections were recorded in 299 patients. One hundred-six patients (26%) had detections due to supraventricular tachycardias, electrical noise or other causes, resulting in inappropriate therapy delivery to 92 patients (23%). Two hundred eighty-one patients recorded 66,276 episodes of ventricular tachycardia or ventricular fibrillation. Of these, 74.4% episodes terminated spontaneously without any delivered therapy, 22.1% terminated after antitachycardia pacing, and 1.7% terminated after shock therapy. Antitachycardia pacing was activated without formal testing in 47% of all patients receiving this therapy and was successful in 96% of all episodes receiving this therapy. Acceleration of tachycardia to shock therapy occurred in 1.3% of all episodes and in 30.5% of patients receiving antitachycardia pacing. Thirty four patients (8.7%) died during follow up. Mortality was associated with patient age, heart failure functional class at implantation and frequency of shocks received during follow-up (all p less than or equal to 0.05). Conclusions. Most ventricular tachyarrhythmia detections by this noncommitted implantable cardioverter defibrillator resolve spontaneously, whereas the majority receiving therapy can be treated with antitachycardia pacing. Mortality after implantable cardioverter-defibrillator implantation is associated with age, heart failure class and frequency of shocks received during follow-up. Data-logging capabilities provide valuable insights into the patterns of defibrillator use.