Evaluation of the Need of Elective Implantable Cardioverter-Defibrillator Generator Replacement in Primary Prevention Patients Without Prior Appropriate ICD Therapy
What are the incidence and predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy after device replacement in patients who received their initial ICD for primary prevention and never experienced an appropriate ICD therapy during the first generator longevity?
Two European centers contributed data from their ICD registries. All primary prevention patients who had a first ICD replacement without previous appropriate ICD therapy were identified. Cox regression analysis was used to identify predictors of appropriate ICD therapy.
Of 403 primary prevention patients needing first ICD replacement, 275 patients (68%) had not received previous appropriate ICD therapy. Patients without previous appropriate ICD therapy before first ICD replacement (mean age at replacement 62 ± 12 years, 75% male) had a mean follow-up of 86 ± 24 months after the initial implantation and 30 ± 24 months after device replacement. Following replacement, 3-year cumulative incidence of appropriate ICD therapy was 13.7% (95% confidence interval [CI], 8.6-18.8%). No predictive factors associated with appropriate ICD therapy after replacement could be identified despite including seven clinically relevant factors.
A considerable number of primary prevention patients without previous appropriate ICD therapy before first ICD replacement received appropriate ICD therapy after replacement. As there were no predictors of appropriate ICD therapy after replacement, replacing an ICD is still recommended in all primary prevention patients despite the lack of appropriate ICD therapy during first battery service life.
This study suggests that primary prevention ICD patients, who did not experience appropriate therapies from their initial generator, are at risk of receiving appropriate therapy after device replacement. Of course, appropriate ICD therapy may not be an adequate surrogate for sudden cardiac death, with the rate of appropriate therapy being significantly lower than the rate of death. Even in patients with improved left ventricular ejection fraction, there are conflicting studies about the usefulness of ICD generator replacement. Definitive answers regarding this issue are hampered by small sample sizes and the retrospective nature of the analyses.
Keywords: Registries, Stroke Volume, Death, Sudden, Cardiac, Defibrillators, Implantable, Primary Prevention
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