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Complications of ICD Replacements
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville
Source: Krahn AD, et al, for the Ontario ICD Database Investigators. Predictors of short-term complications after implantable cardioverter-defibrillator replacement: Results from the Ontario ICD Database. Circ Arrhythm Electrophysiol 2011;4:136-142.
The province of Ontario in Canada maintains a comprehensive database of all implantable cardioverter-defibrillator (ICD) implants. In this paper, Krahn and colleagues examine the complications related to ICD generator changes over a 30-month period from February 2007 to August 2009. Data in the Ontario ICD Database are submitted by the local electrophysiologists and a trained research coordinator at each implant center. Complications were routinely evaluated using a standard checklist and categorized as either major or minor. Major complication required a repeat procedure, hospitalization, or parenteral therapy. The authors then analyzed the data to identify clinical and procedural factors associated with complications.
During the period of this study, there were 1,081 ICD replacement procedures in Ontario. The mean age was 66 years and 82% of the patients were male. Approximately two-thirds of the patients had ischemic heart disease and more than 50% of the devices were placed for secondary prevention. The replacements included 350 single-chamber devices, 383 AV devices, and 348 cardiac resynchronization therapy defibrillator (CRT-D) devices. A total of 88 complications occurred in 47 patients (4.3%). Forty-seven major complications were observed in 28 patients. The most common major complications were pocket infection sepsis (23 patients, 1.7%), lead replacement (16 patients, 1.4%), electrical storm (14 patients, 0.7%), and pulmonary edema (10 patients, 0.9%). Lead extraction was required for 11 leads in nine patients and lead repositioning was required in an additional seven patients. There were six strokes or noncerebral embolism during follow-up and four of these six patients had undergone defibrillation threshold testing at the time of their generator change. Forty-one minor complications were noted in 25 patients. These consisted mostly of incisional infections or pocket hematomas. A number of clinical and procedural factors were associated with an increased risk for complications. Hazard ratios above 2 were noted for the following factors: elevated angina class, prior myocardial infarction, CRT device, more than one previous device procedure, insertion of a new lead, New York Heart association functional class III or IV, surgeon vs nonsurgeon implanter, and documented coronary artery disease. Implanter volume was inversely associated with the risk for complications. Major complications were associated with a substantially increased risk of mortality at 45, 90, and 100 days with adjusted hazard ratios for mortality of 9.6, 12.7, and 6.4, respectively.
The authors conclude that complications are common in patients undergoing ICD replacement and these complications are associated with a risk for mortality.
It has been well recognized that there is a higher risk of complications with pacemaker and ICD generator changes than with the initial implant procedures themselves. At the time of most generator changes, the leads are stable and do not need to be remanipulated. However, the pockets may be extensively scarred and poorly vascularized and careful attention to surgical technique is necessary to prevent future problems. If a new lead has to be inserted as a replacement for a poorly functioning lead or as part of an upgrade, the implanter often has to deal with difficult venous access and must enlarge an already scarred pocket. The shape of the new device may not be the same as the prior unit and this can cause further problems. One of the most common reasons patients are referred to my center for device extraction is an infected or an eroded pocket after a generator upgrade or change. To avoid this, we try to open the pocket widely and break up or resect some of the generators pocket capsule if it's thick.
There is no substitute for very careful surgical technique at the time of ICD generator change or upgrade. One must take care to make sure the pocket size is adequate and that there is no tension on the incision or pressure on the overlying skin. This is particularly a problem if a new lead or a different size or shape generator is to be implanted. The other major issue that arises is what to do with warfarin or antiplatelet agent at the time of generator change. We now usually maintain warfarin or hold it only briefly and avoid use of fractionated or unfractionated heparin. This has markedly cut down on post-operative hematomas, which often are the cause of later infections.