In electrophysiology labs, you sometimes hear a newbie say: "It's just a generator change." Experienced caregivers never say this.

I don't know about your practice, but in mine, implantable cardiac defibrillator (ICD) generator change procedures nearly outnumber new implants. The reason for that trend is, in large part, good news. Good news because people with heart disease are living longer. The bad news is longevity often comes with age-related organ dysfunction and chronic diseases.

Recall that when we implanted an ICD the first time, we gambled. We looked at the patient, hopefully not just the EF, and we took the risk that future device benefits would outweigh harms.

That gamble changes—often for the worse—at the time of generator change. ICD benefit at the time of generator change may decline for two reasons. One is aging and its associated chronic diseases, which increasingly burden the patient with competing causes of death. The other reason is LVEF may have improved. When that happens the risk of sudden death relative to other causes decreases, and those smaller benefits may no longer outweigh the surgical risks.

Numerous real-world studies presented at the European Heart Rhythm Association (EHRA) EUROPACE-CARDIOSTIM 2015 addressed the challenge that comes at the time of elective replacement of ICDs. I like real-world data.

A group from Radboud University Medical Center, Nijmegen, Netherlands, presented a series of 95 patients who came for ICD generator change after a primary-prevention implant[1]. An LVEF at the time of generator change was available in 45 patients. They noted 16 (36%) patients had an LVEF >35%, and 11 of those 16 had LVEFs >45%. The authors concluded LVEF reassessment should be done at the time of generator change, as it would "provide further insight for clinical decision making."

Two physicians from the University of Manitoba, Winnipeg, presented a review of 74 patients who had generator change after primary-prevention ICD implant[2]. They had LVEF assessments at the time of generator change in 69 (93%) patients, of which 19 (28%) showed LVEF recovery. Appropriate ICD therapy (antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation) occurred in 15 (20%) patients after generator change. Improved LVEF associated with fewer appropriate ICD therapies (5% vs 48%, respectively, P<.001). Interestingly, the incidence of appropriate therapy in the second device did not differ between patients who had or did not have therapy with their first device. An honesty alert: Complications requiring surgery occurred in 11 (15%) patients. The unusually pithy conclusion was that primary-prevention patients with improved EF enjoy a lower incidence of appropriate ICD therapy, and the risk of ICD reimplantation is significant. (If I graded abstracts, I'd give these guys high marks for honesty and for skipping the overreach.)

A group from the University of Eastern Piedmont, Novera, Italy, tested the hypothesis that selectively withholding ICD generator change could be safe and cost saving[3]. They looked back at 166 patients who had generator change of a primary-prevention ICD. LVEF >35% was noted in 47 (28%) patients, none of whom had appropriate therapy with their first device. Patients with LVEF improvement were eightfold less likely to receive ICD therapy after generator change, but six patients with LVEF improvement—none of whom had therapy with their original device—received their first ICD intervention after generator change. In a cost analysis, the authors estimated withholding ICD generator changes in patients outside criteria would have saved €680,000—one-third of their yearly device budget. Their concluding statement acknowledged the dilemma of immense cost savings combined with low but not zero risk in patients with LVEF recovery. A potential resolution: "Large prospective trials are needed to assess this topic."

In an oral abstract session, a group from University Hospital in Leuven, Belgium, studied the incidence of appropriate therapy after elective replacement of an uneventful first ICD[4]. They included 727 patients implanted for both primary and secondary prevention. Similar to the Italian group, they found a troubling 23% incidence of first appropriate ICD therapy in patients after generator change. They concluded that "in the case of an uneventful first device, almost a quarter of patients experience their first therapy after replacement."


Taken together, these single-center experiences corroborate findings first published in 2012 by Kini et al in the Journal of the American College of Cardiology—namely, that ejection fraction improvement at the time of generator change above the National Coverage Decision–determined cutoff for ICD eligibility occurs in 20% to 30% of patients[5]. And this group of patients has a low but still significant rate of appropriate therapies after device replacement.

This is a tough situation. When LVEF improves, the risk of arrhythmic death is lower. That fact figures in the generator-change decision, because lower arrhythmic risk reduces the net benefit of the ICD. But that benefit does not go to zero. Missing a preventable death in someone with a good heart is a big loss. Finally, add in the problem of competing causes of mortality, and the generator change decision gets even harder.

Costs, too, cannot be left out of this discussion. As the number of generator changes increase, small gains in risk stratification at the time of replacement would result in big savings. As I have said before, if we waste money on low-value treatments, we have less to spend on other important things. We don't print money in healthcare.

I think a clinical trial of generator-change surgery would be a terrific use of research dollars. I am hopeful but realistic. It's unlikely to happen. Recruitment of patients would be tricky. I'm trying to picture the informed-consent process in which we randomize ICD patients to no more device. Also, I doubt device companies would fund a study that may lead to fewer implants. Cardiologists, too, might not be enthusiastic about a trial that could be unfavorable to devices.

Let's close with certainty: I am certain patients are the experts on what is best for them. We can't know a person's goals for care, risk tolerances, or feelings about trade-offs unless we have the conversation. The decision to replace or not replace an ICD is a terrific opportunity for slow doctoring, which leads to good doctoring.



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