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The implantable cardioverter defibrillator as a "bridge to transplant": a viable clinical strategy?
1Department of Cardiology, University of Vienna, Austria.
Insights
Patients awaiting heart transplants face death from pump failure or sudden arrhythmias. Implantable cardioverter defibrillators (ICDs) effectively treat arrhythmias, but their benefit may be limited by pump failure. Prophylactic ICDs warrant consideration.
Area of Science:
- Cardiology
- Transplantation Medicine
- Medical Devices
Background:
- Heart transplantation is a vital treatment for end-stage heart disease.
- Donor organ scarcity leads to extended waiting times and increased mortality for recipients.
- Approximately 20% of patients awaiting heart transplants die before receiving one.
Purpose of the Study:
- To evaluate the efficacy and role of implantable cardioverter defibrillators (ICDs) in patients awaiting heart transplantation.
- To assess the impact of ICD therapy on sudden cardiac death and overall survival in this high-risk population.
Main Methods:
- Analysis of pooled data from sudden death survivors listed for cardiac transplantation.
- Evaluation of ICD therapy's safety (mortality, morbidity) and efficacy (appropriate shocks).
- Consideration of competing risks of death from pump failure versus ventricular tachyarrhythmias.
Main Results:
- ICD therapy in transplant candidates demonstrated low mortality and morbidity with high efficacy (94% received appropriate shocks).
- Sudden tachyarrhythmic death accounts for a smaller fraction of deaths compared to pump failure in this group.
- The survival benefit of ICDs may be offset by the risk of death from progressive pump failure.
Conclusions:
- Prophylactic ICD implantation may be considered as a bridge to transplant in advanced heart failure patients.
- Further prospective randomized studies are necessary to definitively establish the role of prophylactic ICD therapy in heart transplant candidates.
- Risk stratification for sudden tachyarrhythmic death has limited value in advanced heart failure.
Abstract:
Heart transplantation is an accepted therapeutic option for patients with end-stage heart disease. However, because the availability of heart donors fails to keep pace with the growing demand, increasing numbers of potential recipients are placed on the waiting list, resulting in longer waiting times. About 20% of patients die while awaiting heart transplantation. The majority die from progressive pump failure (46%), whereas about 30% of all deaths occur suddenly. Monitored terminal cardiac electrical activity in patients dying while awaiting transplantation reveals that bradyarrhythmias and/or electromechanical dissociation are involved in 68% of cases and ventricular tachyarrhythmias in 32% of cases. Patients with a history of aborted cardiac arrest are at highest risk for recurrent malignant arrhythmias. The implantable cardioverter defibrillator (ICD) is the most effective therapy for preventing sudden cardiac death from ventricular tachyarrhythmias. Pooled data from a total of 75 sudden death survivors listed for cardiac transplantation demonstrate that ICD therapy can be applied with low mortality, low morbidity, and high efficacy, with up to 94% of the patients receiving appropriate shocks during the waiting period. However, there is considerable concern that this early survival benefit conferred by the ICD may be nullified by the competing risk of death due to terminal pump failure, as the waiting list and waiting time to transplantation lengthens. In advanced heart failure, risk stratification for sudden tachyarrhythmic death is only of limited value. Therefore, although sudden tachyarrhythmic death appears to constitute only a minor fraction of total cardiac death in patients awaiting heart transplantation, prophylactic ICD implantation as on electronic bridge to transplant may be considered. To define conclusively the role of prophylactic ICD therapy in this setting, prospective randomized studies are needed.