ICD Complications Are More Common in CRT, Dual-Chamber Devices

Reed Miller

February 26, 2010

February 26, 2010 (Toronto, Ontario) — Patients who receive a dual-chamber or resynchronization devices, women, and patients with an enlarged left ventricle are at significantly higher risk for complications with implantable cardioverter defibrillators (ICD), according to data from the Ontario ICD Database [1].

Dr Douglas Lee (Toronto General Hospital, ON) and colleagues examined 45-day complications and all-cause mortality in 3340 patients at 18 centers in Ontario from 2007 to 2009. The results, published in the February 23, 2010 issue of the Journal of the American College of Cardiology, show that major complications occurred in 4.1% of de novo ICD implant procedures and that the most significant factor associated with complications is the type of ICD implanted.

"Our results suggest that clinicians should consider whether a simpler defibrillator can be used instead of the more complex devices," Lee told heartwire . "The consideration of complications should factor into the decision regarding the type of ICD used."

Commenting on the study for heartwire , Dr Matthew R Reynolds (Beth Israel Deaconess Medical Center, Boston, MA) points out that the Ontario results affirm the findings of the National Cardiovascular Data Registry Implantable Cardioverter Defibrillator Registry (NCDR ICD) that the rate of complications rises with the complexity of the device, but he added, "The link between procedural complications and subsequent mortality in this study was rather striking.

"This finding highlights the importance of patient selection and should remind implanting physicians that the extra risk entailed in using the more complex devices should always be justified by the expected benefit, and single chamber devices should be preferred in the absence of an accepted indication for a dual-chamber or CRT device," Reynolds said. "Also, because patients with more diseased ventricles had higher complication rates, this suggests that, whenever possible, patients should be 'tuned up' medically before undergoing an elective ICD implant."

The risk of major complications with cardiac resynchronization defibrillators (CRT-D) was more than twice that with single-chamber devices. The risk of major complications with dual-chamber devices was almost twice that with a single-chamber device. Device type had an even greater effect on the complication rate in patients getting an ICD for primary prevention of sudden cardiac death.

Lee et al say their study is novel in the field of ICD-complications analysis in that all the data were collected from a prospective population-based registry, with detailed longitudinal follow-up using both clinical-device and passive administrative data. Because the registry was mandated by the administrator of healthcare services in Ontario for all defibrillator-implanting centers in the province, the study was not subject to volunteer bias, and patients of all ages were enrolled.

Complications were categorized as major or minor on the basis of the consensus of electrophysiologists from all the participating hospitals. Major complications were generally those that required a follow-up operation to revise the lead or device or for therapeutic relief. Examples of major mechanical complications include myocardial perforation, skin erosion, pocket infection, and lead dislodgement. Some of the major clinical complications tracked were sepsis, stroke, and electrical storm.

Major complications were increased in women and in patients with a left ventricular end-systolic dimension greater than 45 mm. Major complications, other than death, arising early after ICD implantation were associated with 3.7 times greater risk of subsequent death up to six months after the implant. Direct implant-related complications multiplied the risk of near-term death almost 25 times, while indirect clinical complications increased that risk by about 12.

Minor complications included incisional infection, site pain, and pocket hematoma. "Minor complications remain clinically important because these events may influence quality of life, but further data are needed to determine the degree of this association," the authors note.

Multivariable Predictors of Major Complications With ICDs

Characteristic Hazard ratio 95% CI p
Women 1.49 1.02–2.16 0.037
Secondary vs primary prevention 1.45 0.97–2.16 0.071
LV end-systolic dimension >45 mm vs <45 mm 1.54 1.08–2.20 0.018
Dual vs single-chamber ICD 1.82 1.19–2.79 0.006
CRT-D vs single-chamber ICD 2.17 1.38–3.43 <0.001

Complications Follow Complexity

Early mortality in patients with major complications could be the direct result of a mechanical procedure-related event, and these mechanical complications might be linked to the increasing procedural complexity of implanting dual-chamber and CRT devices, which require more leads than single-chamber devices.

In the patients getting a device for the primary prevention of sudden death after MI, anticoagulation or antiplatelet agents could have contributed to the increased risk, the authors suggest. The increased risk in the primary-prevention population "is particularly relevant given the tendency of some to implant defibrillators without discontinuation of oral anticoagulants combined with bridge therapy," Lee et al explain.

The mortality effects of indirect clinical complications lasted at least six months after implantation, suggesting that progression of the underlying cardiovascular disease predisposes the patient to a higher a priori risk of death. In particular, the link between enlarged left ventricles and complications suggests that altered biventricular and atrial geometry increases the risk of mechanical and clinical complications.

Implanting physicians in Ontario are very experienced and specifically trained to implant the devices, so the data show that complications are not uncommon even with experienced physicians, Lee noted. Although the Ontario registry did not specifically look at physicians' training and experience, the data may suggest that ICD-implant training programs should monitor the complication rates of their trainees, such as logging complications of ICD implants for electrophysiology fellows and providing feedback on how to reduce complications in the future, Lee said.

Reynolds points out that, given the experience of the Ontario physicians, the implication of Lee et al's findings is that doctors with less optimal training and experience than those in Ontario will have even worse outcomes. As reported by heartwire , data from the NCDR ICD registry show that ICD implantations by nonelectrophysiologists are more likely to have complications.

More Research Needed on Combinations of Risk Factors

"Because direct implant-related complications and indirect disease-related major perioperative events were associated with an increased risk of death, further evaluations of early defibrillator complications, their potential effects on mortality, and preventive strategies are needed," the authors add.

"We need longitudinal registries to monitor complications and safety of defibrillators. These complication data could then be fed back to the implanting physicians to allow them to implement ways to reduce such complications," Lee said. "Randomized trials of interventions that can reduce major complications may also be useful in the future as well."

The authors note that the effects of various risk factors can be complex and increase risk through combinations of complications and subcomplications. Also, intraoperative factors such as the duration of the implant procedure were not examined in this study, although the more complex devices usually take longer to implant.

The results suggest that complication rates are driven not only by the type of device and the difficulty of the implant procedure, but by the underlying disease of the patient, which should be treated to lower the risk of complications before defibrillator implantation, especially in patients referred for a CRT-D device, who are at the greatest risk of heart-failure–related complications, the authors explain.

"I don't think we've done enough to systematically identify and promulgate best practices in this area," Reynolds said. "We need quality-improvement research, and, although challenging to do, more studies examining which surgical practices--anticoagulation management, antimicrobial prophylaxis, choice of leads and lead types, etc--work to prevent complications and which do not."

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