ICD duel: Lower complication rates with single-chamber devices

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Patients implanted with dual-chamber implantable cardioverter-defibrillators (ICDs) had higher rates of complications at one year than did patients who received single-chamber devices, with no apparent benefits in hospitalization or mortality. The results were published in the May 15 issue of the Journal of the American Medical Association.

Randomized clinical trials to assess the efficacy of ICDs for primary prevention of sudden cardiac death generally evaluated single-chamber ICDs. They also included a select patient population that was younger and healthier than seen in contemporary practice. But in the real-world setting, many patients receive dual-chamber devices.

Pamela N. Peterson, MD, MSPH, of the Denver Health Medical Center, and colleagues designed their study to compare outcomes in patients without a pacing indication who were implanted with single- or dual-chamber ICDs for primary prevention of sudden cardiac death. “Because implanting a dual-chamber ICD is a more complex and time-consuming procedure than implanting a single-chamber device, the possibility of device-related complications such as infection and lead displacement requiring device revision is likely to increase,” they wrote.

Using admissions data from the National Cardiovascular Data Registry’s ICD registry, they identified 32,034 patients from 1,270 hospitals in the U.S. who received devices between 2006 and 2009 and could be matched to Centers for Medicare & Medicaid fee-for-service data. Outcomes of interest included mortality, hospitalizations and implant-related complications at one year.

Sixty-two percent of the patients in the study received dual-chamber devices and 38 percent single-chamber ICDs. The choice of single- or dual-chamber device appeared to be “relatively random,” based on patient characteristics, they determined.

After propensity score matching, they found the rate of complications was lower in the single-chamber device group, at 3.51 percent vs. 4.72 percent for the dual-chamber device group. The greatest difference was observed for mechanical complications requiring reoperation for system revision, at 1.43 percent vs. 1.98 percent.

There were no differences at one year in rates of all-cause hospitalization, heart failure hospitalization or mortality. Dual-chamber ICDs were associated with higher complication rates in a subgroup analyses as well, with women in particular showing a higher rate of complications, at 6.43 percent for dual-chamber devices and 4.68 percent for single-chamber devices.  

“In this large national cohort of Medicare patients, dual-chamber devices did not have any observed advantage with regard to mortality or hospitalization compared with single-chamber ICDs,” Peterson et al wrote.

Their results reflect outcomes for a real-world group of elderly patients, with findings that expand on previous research by discriminating between single- and dual-chamber devices. But the study had limitations, including being observational and lacking data on device settings, outcomes such as quality of life and the development of atrial fibrillation and upgrades from single- to dual-chamber ICDs.

Dual-chamber ICDs may offer benefits that were not assessed in the study, such as potentially reducing inappropriate shocks, they acknowledged. However, dual-chamber devices carry higher costs.  

“Despite the absence of compelling evidence to support these more costly devices, which are also associated with higher complication rates, current practice is highly variable,” they observed. “Our study does not provide evidence that would support the more costly and more morbid device for patients receiving an ICD for primary prevention.”

They suggested more research to evaluate the tradeoff between increased complications and the potential reduction in inappropriate therapy with dual-chamber ICDs, and recommended that physicians “consider carefully” before implanting dual-chamber devices in patients without pacing indications.