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When is it safe not to replace an implantable cardioverter defibrillator generator?
P Tchou1, K Axtell, A J Anderson
1University of Wisconsin, Sinai Samaritan Medical Center, Milwaukee.
Pacing and Clinical Electrophysiology : PACE
|November 1, 1991
Summary
Patients receiving implantable cardioverter defibrillators often experience appropriate shocks within the first two years. This study suggests a bimodal shock distribution, with a notable rise in the fifth year, impacting device replacement decisions.
Area of Science:
- Cardiology
- Medical Devices
- Electrophysiology
Background:
- Implantable cardioverter defibrillators (ICDs) are crucial for managing ventricular tachyarrhythmias.
- Previous reports indicate most shocks occur within the first 2-3 years post-implantation.
- This raises questions about the necessity of ICD replacement if no shocks are delivered.
Purpose of the Study:
- To analyze shock experience in patients with implantable cardioverter defibrillators.
- To determine the long-term need for device replacement based on shock history.
- To investigate the timing and incidence of appropriate shocks.
Main Methods:
- Retrospective analysis of shock experience in 184 patients receiving ICDs.
- Mean follow-up duration of 24 months (±18.7).
- Appropriate shocks defined by electrocardiographic documentation of sustained ventricular tachyarrhythmia or preceding presyncope/syncope.
Main Results:
- 68 patients (37%) received at least one appropriate shock during follow-up.
- Over 90% of these patients received their first shock within 2 years post-implant.
- Actuarial risk of an appropriate shock by year 5 was 69%, with a bimodal distribution observed.
Conclusions:
- A significant portion of patients experience appropriate shocks within the first two years.
- The study suggests a bimodal shock incidence, with a potential increase in the fifth year.
- Findings inform decisions regarding ICD longevity and replacement strategies.