Incidence of defibrillator shocks after elective generator exchange following uneventful first battery life.
BACKGROUND
A significant number of implantable cardioverter-defibrillator (ICD) patients do not experience shocks after ICD implant. Elective generator exchange (GE) has been associated with increased risk of infection and ICD lead failure. There is a paucity of contemporary data reporting on shock incidence with replacement devices.


RESULTS
Patients undergoing elective GE (n=24 203) who transmit data remotely via a remote monitoring system were analyzed to determine the incidence of ICD shocks after GE. A total of 16 230 patients (67%) did not experience a shock with the first ICD (group A), and 7973 (33%) received at least 1 shock (group B). Patients in group A were older (71.3 versus 68.8 years, P<0.001) and more often female (71% versus 77% male, P<0.001). Over an average follow-up of 1.9±1.2 years after GE, the proportion of patients with shocks and risk of ICD shocks was lower for those who did not receive a shock during the first battery life (group A: 9.9% versus 27.7%, hazard ratio 0.36, 95% CI 0.34 to 0.38, P<0.001). The cumulative rate of ICD shocks at 5 years after GE was 25.7% in group A and 51.1% in group B.


CONCLUSIONS
In this large cohort of ICD patients implanted across the United States, two thirds did not receive ICD shock therapy prior to GE. The occurrence of ICD shocks prior to GE is an important predictor of shocks after GE; however, even among those without shocks during first battery life, the incidence of shocks at 5 years following GE is >25%. These data should support informed decision making for patients and physicians at the time of ICD generator end of service.
Cardiology Division, Emory University School of Medicine, Atlanta, GA (F.M.M., M.S.L.).
Faisal M
FM
Merchant
Boston Scientific Corporation, St. Paul, MN (P.J., S.W.).
Paul
P
Jones
Boston Scientific Corporation, St. Paul, MN (P.J., S.W.).
Scott
S
Wehrenberg
Cardiology Division, Emory University School of Medicine, Atlanta, GA (F.M.M., M.S.L.).
Michael S
MS
Lloyd
Cardiology Division, University of Southern California, Los Angeles, CA (L.A.S.).
Leslie A
LA
Saxon
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D020878:Device Removal / Q000009:adverse effects*; D004554:Electric Countershock / Q000009:adverse effects* / Q000295:instrumentation*; D011211:Electric Power Supplies / Q000009:adverse effects*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D058998:Remote Sensing Technology; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
defibrillation; electrophysiology; sudden death