Routinely Replace Initial Primary-Prevention ICDs? Maybe Not

April 09, 2014

PHILADELPHIA, PA — By the time patients with a first primary-prevention implantable cardioverter defibrillator (ICD) are due for a new device, about one-fourth no longer fulfill indications for such an ICD and as a group have a reduced risk of later needing appropriate device therapy, suggests a retrospective analysis[1].

Such patients are often those who were initially implanted when LVEF was in the high range of eligibility, 30% to 35%, and later improved without the device having ever delivered appropriate therapy, according to the study published online today in the Journal of the American College of Cardiology.

"This finding would suggest that generator replacement may not always need to be performed in this population and that the lack of distinction between initial implantation and generator replacement in existing guideline criteria for appropriate use of primary-prevention ICDs may be reasonable," according to the report.

That is, the analysis suggests that when such an ICD with low power reserves would typically be replaced, failure to again meet appropriate-use criteria could conceivably be grounds for not replacing it. Not only are the guidelines on indications for primary-prevention ICDs blind to whether it's a first or replacement device, so is Medicare coverage, the report notes.

One of the study's messages may be that "patients who come up for a generator change should have some recent assessment of their LV function to recognize whether the ejection fraction has gotten better or not," senior author Dr Sanjay Dixit (University of Pennsylvania and Philadelphia VA Medical Center) told heartwire . That's especially applicable if their LVEF was >30% when initially getting the device, he said, "because there's a good chance they might have improved."

The analysis, according to Dixit, found that a third of primary-prevention ICD patients had not recently had an assessment of LV function, even though they had never received an appropriate therapy.

Data Support and Extend Prior Studies

The study of an admittedly limited male VA cohort getting first primary-prevention devices from 2006 to 2013, with first author Dr Vinay Kini (University of Pennsylvania), support and extend some prior observational analyses suggesting that the risk of needing ICD therapy after a first generator change is fairly low.

Still, other observational data suggest the opposite, Dixit said, and in practice a generator change is seldom withheld, unless the patient has a terminal comorbidity. So "until such time that we have a [prospective] study, I don't think we can clearly say that we should withhold changing the generator." That study, he proposed, would include patients who no longer meet the device indications and would be offered the options of a new generator or no generator change.

The current analysis looked at the records of 231 patients at two tertiary Veterans Affairs centers receiving generator replacements an average of five years after implantation with their first primary-prevention ICDs.

Of those 231, 26% no longer had an LVEF <35% at a recent evaluation and hadn't had an appropriate therapy; for purposes of the analysis, a replacement ICD was considered "not indicated" for them. After they received the new generator, they experienced appropriate ICD therapy at the rate of 2.8% per person-year (follow-up 3.5 years).

In 40%, a replacement was considered "indicated" based on recent LVEF assessment or because they had received appropriate therapy from their first device. After device replacement, their rate of appropriate therapy was 10.7% per person-year (p<0.001 compared with the "not-indicated" group).

In multivariate analysis, the only predictor of no longer meeting ICD criteria at generator-replacement time was an LVEF of 30% to 35%, compared with <30%, at the initial ICD implantation (p=0.01).

A Case for Explant, Not Replacement

The current analysis along with other prior observational studies "make a case for performing ICD explant instead of generator replacement in patients who experience no appropriate therapies and show significant improvement of LVEF" by the time replacement is due, according to the authors.

"In the cases where improvement of LVEF has occurred with the original device being CRT-D, a CRT-P device could be used instead of CRT-D for replacement," they write, meaning biventricular pacemakers that also defibrillate or pace only, respectively.

Dixit pointed out that nonischemic cardiomyopathy, compared with ischemic, fell short as a significant predictor of LVEF recovery (p=0.09). He said it might have turned out significant had there been more patients in the analysis, noting that many electrophysiologists already believe that nonischemic cardiomyopathy, compared with ischemic, has a better chance of improving over time.

So, he said, among patients getting an echocardiogram, "this may be a group where you may want to look at it even more than other groups, in terms of revaluating the LVEF prior to generator change."

"Reasonable to Have a Discussion with the Patient"

According to Dr NA Mark Estes III (Tufts University School of Medicine, Boston, MA), "The author's conclusions are bold when considered in the context of the limitations of the data and other available evidence."

Still, Estes states in an accompanying editorial[2], the current analysis does "support the case to perform ICD explants instead of generator replacement in patients with no appropriate therapies and significant improvement of LVEF." But even the current data aren't enough to resolve the issue, given the current evidence base on optimal criteria for primary-prevention device replacement, he writes.

Until prospective studies resolve the issue, "if the LVEF improves at the time of reevaluation such that a patient no longer meets implantation criteria and they have not had appropriate therapy, it is reasonable to have a discussion with the patient regarding the risk of replacement and uncertain benefit."

Assuming an informed discussion of risks and expectations, he writes, "Ultimately, in the setting of uncertainty, a deferential approach to patient preference is always a prudent approach. Electively withdrawing a potentially life-sustaining therapy such as an ICD by not replacing is justified and appropriate from both an ethical and legal perspective."

Dixit reports receiving a research grant from Medtronic and fellowship support from Boston Scientific, Medtronic, and St Jude Medical. Kini had no disclosures. Disclosures for the coauthors are listed in the paper. Estes discloses consulting for Boston Scientific, Medtronic, and St Jude Medical.

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