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Arrhythmia/EP

US registry points to substantial risk from ICD, pacemaker replacement

May 18, 2009 | Steve Stiles

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Boston, MA - Three years ago, a Canadian group made news when they reported a 5.8% three-month rate of major complications related to the replacement of implantable cardioverter defibrillators (ICDs) that were subject to a safety advisory or "recall" [1]. Sounds high, said some implanters, especially in the US. But the numbers from a Canadian Heart Rhythm Society working group had breached what had been nearly a vacuum with respect to large-cohort data on the safety of replacing either ICDs or pacemakers.

Attendees at the Heart Rhythm Society 2009 Scientific Sessions last week got a glimpse of some of the first such US numbers associated with implanted-device change-outs from a sizable cohort. A preliminary, unadjusted analysis, presented here by Dr Marye J Gleva (Washington University School of Medicine, St Louis, MO), suggested that the risk of major complications from ICD change-outs may actually be similar north and south of the world's longest shared international border.

In the analysis of 1031 patients from a multicenter registry called REPLACE, who received replacement ICDs or pacemakers without planned lead revision or replacement during a recent one-year period, about 11% developed complications of some kind over the six-month follow-up; that rate included infections in about 1.3% of the cohort.

The rate of major complications, including serious infections or hematomas, was 4.2%. Minor complications like swelling at the pocket site or need for reprogramming occurred in 7.3%.

About half the replacements were of ICDs and half were of pacemakers. The rate of major complications differed substantially between the two device types, at 6.0% and 2.5%, respectively.

All complications documented in the registry had been prospectively defined and were independently and blindly adjudicated, Gleva reported.

Now we have compatible data that should give most implanters real pause prior to explanting an advisory generator.

The raw numbers should be considered only hypothesis-generating, she told heartwire, but already she has heard from colleagues that they seem "higher than expected." They potentially provide, however, the kind of information clinicians need to reliably gauge the risks vs benefits of device replacement when, for example, an ICD or pacemaker is the focus of a safety advisory.

"It's nice to have US data that is in concert with the Canadian data," REPLACE principal investigator Dr Jeanne Poole (University of Washington School of Medicine, Seattle) said to heartwire. "A lot of us couldn't believe that the complication rate actually might be that high. And now we have compatible data that should give most implanters real pause prior to explanting an advisory generator, unless the risk of the problem with that generator is significant over time."

The presented analysis didn't look at the cumulative risks of repeated device change-outs, according to Poole, but "probably for most recalls and advisories, the risk of explanting and reimplanting new generators is going to be many times greater than that of following the patient closely."

The 1031 REPLACE patients received their replacement devices at 68 US centers, had their surgical wound checked within one to seven weeks, were evaluated at three months, and had their final clinic visit at six months. Their mean age at baseline was 71 years; 29% had diabetes, 14% had elevated creatinine; about half were on aspirin, 11% were taking a thienopyridine, and 37% were on warfarin.

All received preoperative antibiotics and antiseptic preparation of the implant site; 82% received antibiotic irrigation of the pocket, about half had postprocedure IV antibiotics and half received oral antibiotics after discharge.

They were experienced implanters who have been in the business a long time. . . . My suspicion is that we won't see a great variance across different centers.

The 53 major complications that occurred in 43 patients included device malfunction requiring reopening of the pocket in 21% of such cases, readmission related to the new device in 17%, hematoma in 15%, infection in 13%, "prolonged" hospitalization in 11.3%, pocket revision in 7.6%, and a host of less common "other" complications in 15%.

Six patients died within 30 days of the implantation, but at adjudication none were considered to be a direct result of the procedure, according to Gleva.

The 83 minor complications experienced by 75 patients included visible swelling in 29% of the cases, blistering in 19.3%, hematoma in 15.7%, cellulitis and device reprogramming in 7.2% each, and various "other" ones in 21.7%.

Proportion of patients with each device type who experienced at least one major or minor complication

Device	Major complication (%)	Minor complication (%)
All pacemaker	2.5	6.2
Single-chamber pacemaker	2.2	7.8
Dual-chamber pacemaker	2.6	5.9
CRT pacemaker	0	7.1
All ICD	6.0	8.4
Single-chamber ICD	5.0	8.9
Dual-chamber ICD	4.9	7.5
CRT-D	8.0	9.1

CRT=cardiac resynchronization therapy, ICD=implantable cardioverter defibrillator, CRT-D=CRT-defibrillator

To download table as a slide, click on slide logo above

Both major and minor complications hit at similar rates for dual- and single-chamber devices, whether they were pacemaker-only or could defibrillate. But the major complication rate was sharply higher for ICDs than for pacemakers.

"The centers that participated in our study all did moderate to high volumes of these procedures," according to Poole. "And they were experienced implanters who have been in the business a long time. Although we haven't [yet] done this analysis, my suspicion is that we won't see a great variance across different centers. I think [our data] actually do reflect true complication rates related to routine pacemaker and ICD generator changes."

Biotronik sponsors the REPLACE registry. Gleva discloses receiving consulting fees/honoraria and research support from Biotronik and Medtronic. Poole reports being on the speakers' bureau for Boston Scientific, Medtronic, and St Jude Medical and receiving research grants from Biotronik.

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Source

1. Gould PA, Krahn AD, for the Canadian Heart Rhythm Society Working Group on Device Advisories. Complications associated with implantable cardioverter-defibrillator replacement in response to device advisories. JAMA 2006; 295:1907-1911.