Significant differences in the expected versus observed longevity of implantable cardioverter defibrillators (ICDs).
BACKGROUND
Implantable cardioverter defibrillator (ICD) is a life-saving therapy for patients at risk of ventricular arrhythmias. Due to its high cost, its cost-effectiveness is highly dependent on its longevity, which is currently only based upon the manufacturer's predicted device life span.


OBJECTIVE
We sought to assess the ICDs' longevity and the factors influencing it, and to compare the observed (real life) to the expected (manufacturer's prediction) life span at a device level.


METHODS
We retrospectively identified all patients who underwent an ICD implantation in a tertiary care medical center. For each device, an expected longevity was assigned based on the manufacturer/model, pacing percentage, and number of shocks per year. We defined device failure if the observed survival was shorter than 80 % of the expected. Only devices with follow-up time that exceeded the expected longevity were included.


RESULTS
Of the 275 devices in the cohort, 79 (29 %) failed. Median device longevity was 5 years and varied markedly between manufacturers (4.3, 4.8, 5.1, and 6.3 years for Biotronik, St. Jude Medical, Boston Scientific, and Medtronic, respectively). There were significant differences among the manufacturers in device failure rates: 48, 17, 22, and 14 % for Biotronik, St. Jude Medical, Boston Scientific, and Medtronic, respectively). In multivariate analysis, manufacturer, earlier year of implantation, congestive heart failure and chronic renal failure significantly predicted device failure.


CONCLUSIONS
In conclusion, there is a significant device failure rate among ICDs, with variability among manufacturers, impacting both patients and the medical economic systems.
Department of Cardiology, Soroka University Medical Center, POB 151, 84101, Beer-Sheva, Israel.
Tali
T
Shafat
Yael
Y
Baumfeld
Victor
V
Novack
Yuval
Y
Konstantino
Guy
G
Amit
D000368:Aged; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D062606:Tertiary Care Centers; D013997:Time Factors