Techniques for Device Infection Prophylaxis: Interview With Grant Simons, MD

In this feature interview, we speak with Dr. Grant Simons about his infection prevention practices utilizing the TYRX^™ Antibacterial Envelope. Dr. Simons is the Chief of Cardiac Electrophysiology at Englewood Hospital and Medical Center, and Clinical Assistant Professor of Medicine at Mt. Sinai School of Medicine in New York City. 

How prevalent is cardiac device infection? Tell us about the overall morbidity and mortality rates associated with device infection.

Its prevalence is significant and likely increasing. Published series report the incidence of CIED Infections in different patient populations anywhere from about 2% on up. There have been some probable outliers, but nevertheless, published series of revision procedures show infection rates of up to 5-7%. This is a significant source of morbidity, mortality, and cost. Chronic leads which become infected need to be removed with advanced extraction techniques usually requiring laser; however, laser extractions actually have the highest mortality of any procedure that electrophysiologists perform, and that mortality has been reported as approaching 0.3% in the modern era. So certainly an infection of a chronic system can lead to mortality. The overall mortality associated with device infections is higher than among those patients with devices that aren’t infected. It’s also a very expensive problem to treat because device infections generally require removal of the device, post-operative care, fairly long antibiotic therapy, and reimplantation of the device. When you add all that up, it’s quite expensive. 

What are your current practices for device infection prophylaxis? 

We of course use pre-operative antibiotics and meticulous skin preparation in all patients. Beyond that, we look at each patient’s risk factors for infection and also try to assess just how serious an infection would be in that particular patient. For example, new implantations versus revisions and replacements is the first important distinction. We know that if a chronic system were to become infected, that is a much bigger procedure to deal with in terms of associated morbidity and mortality, compared to a new system where removal would be easier and not a procedure that would require advanced extraction techniques. Therefore, we take extra precautions with all revision and replacement procedures involving chronic leads, because we know infections in such patients are not only more common, but more morbid and possibly lethal. In addition, we look at patients’ individual risk factors for infection. These risk factors have been fairly well characterized in several retrospective published series, and there are three main risk factors for infection that have repeatedly been shown to pose higher risk than others. Renal insufficiency or failure, use of steroids, and early reintervention into the pocket (e.g., for hematoma) are all associated with a many-fold increase in subsequent pocket infection. Therefore, those are the factors we are most concerned about when trying to reduce patients’ risk. In addition, there are some other risk factors that are significant, although not as extreme as the previous three factors that I just mentioned. Those would include presence of a temporary pacing wire, presence of congestive heart failure, and use of anticoagulants, because we know that patients who develop hematoma can then have it become infected. Among patients receiving a new implant, we generally are not as concerned about using resources to prevent infection, unless they have multiple risk factors. 

How long have you been using the TYRX Antibacterial Envelope, first with the non-absorbable, and now with the absorbable version. What can you tell us about your experience with this product?

We were early adopters of this technology — we began using the non-absorbable Envelope shortly after it was cleared by the FDA in 2008. We use the absorbable Envelope in certain cases, but since it is more expensive, we try to use the non-absorbable Envelope when possible. For example, we would use the non-absorbable Envelope in a 90-year-old patient undergoing pacemaker generator replacement. Such a patient would have chronic indwelling leads, and we know that if they were to become infected, it would be a very morbid and possibly lethal event because then we would have to perform extraction in a patient at higher risk due to advanced age. In addition, device longevity is so good these days that it’s fairly unlikely that a 90-year-old patient will make it back to the laboratory for another generator replacement; therefore, we’re not particularly concerned with having to dissect out a non-absorbable Envelope in the future. So for this particular pacemaker generator replacement, we would prefer to save a few dollars and use the non-absorbable Envelope. However, in a 50-year-old patient undergoing defibrillator generator replacement, we would use an absorbable Envelope. This will help minimize the risk of an infection in the setting of chronic leads, but it is also highly likely that this patient will make it back to the laboratory in his or her lifetime for another generator change, and we don’t want to have to dissect out the Envelope next time. I should note that dissecting out a non-absorbable Envelope isn’t that technically demanding — it’s something that you become adept at fairly quickly and doesn’t add too much time to the procedure, although there is a slightly higher risk of bleeding.

What was your pre-envelope infection rate, and how does it compare with your post-infection rate using the TYRX Antibacterial Envelope?

There is no question that, since 2008, our practice has seen a reduction in infection rate. Before FDA clearance of the TYRX Antibacterial Envelope, we were seeing a 1-1.5% infection rate among our revision and replacement procedures, which is fairly representative of the national norm. Since we’ve started using the Envelope for all of our revision and replacement procedures, we’ve had very few infections — our infection rate is well under 0.5%. It has become very rare to see pocket infections; in fact, I can think of only a single case over the last few years.  I think that our targeted use of the TYRX Antibacterial Envelope has greatly benefited our patients. 

The other thing I would say is that patients these days are on more anticoagulants and antiplatelet agents than they used to be, and they’re also on more powerful antiplatelet agents than they previously were, and we’re performing procedures on therapeutic anticoagulation, which wasn’t the case 5-10 years ago. Now, although we know that continuing therapeutic anticoagulation for these procedures is better than using bridging with heparin or enoxaparin, it’s still the case that the presence of anticoagulants increases the risk of hematoma and infection compared with the absence of anticoagulants. So we’re dealing with a patient population that is at higher risk of hematoma and subsequent infection, and that I think has driven our use of this technology to some extent. 

Discuss your involvement in the COMMAND Study as well as the Citadel and Centurion Studies. 

I was involved in those trials and I’m also an investigator in the new WRAP-IT Study. I was an author on the COMMAND Study, and EHMC was a site for Citadel and Centurion.  We recruited a large number of patients into those studies. I was one of the authors on the abstracts that were presented, and I will be one of the authors on the manuscripts that are currently being written for Citadel and Centurion. The COMMAND Study was a retrospective study, and Citadel and Centurion were non-randomized prospective studies — the comparison was to risk-matched controls and to a benchmark published infection rate of 2.2%. The WRAP-IT is the first prospective, randomized study of the TYRX Antibacterial Envelope technology. WRAP-IT will evaluate patients undergoing CIED generator replacement and revision procedures, and patients will be randomized to an absorbable Envelope versus no Envelope. We’re very excited about the WRAP-IT Study, because although the COMMAND, Citadel, and Centurion Studies have of course been very promising, and other published data have also been quite promising, we clinicians prefer randomized studies for obvious reasons. I think that this trial, which was made possible by the acquisition of TYRX, Inc. by Medtronic and a subsequent injection of resources into the study program, is really going to be the final say on this technology. I expect that, once the randomized study is published, the Envelope will become a generally accepted standard of care among those physicians who aren’t currently using the technology. 

How has using the TYRX Antibacterial Envelope also helped your facility with cost savings?

Although we have not performed a formal cost-benefit analysis, we know that infections are very expensive. A device infection has become a no-pay event for Medicare, so it is an expensive event for the facility. Paying up front for each case by purchasing an Envelope is less expensive than the overall cost of dealing with a 2% or higher infection rate, so it’s likely an economic win for the institution. There are one or two published studies that have modeled the costs of a replacement device, treating an infection, and an Envelope. The data from these studies suggested that at least in higher risk patients, the economics are favorable for institutions to pay for an Envelope for their patients to avoid the subsequent costs of dealing with infection. Even if it weren’t economically favorable, it would still be clinically favorable for our patients. It really is an added bonus for institutions and their administrators that while doing good for a patient, we might actually in the long run save the hospital some money as well.  

Infection prevention seems to be a very hot topic these days. Are there any other new technologies that you have seen in the market that you are keen to add to your infection prevention practices?

Yes, it’s a hot topic because infection is so expensive to deal with and causes so much morbidity and mortality to patients. We have been really pleased with how our patients have done since we started using the Envelope; because our infection rate has dropped so drastically, and we are therefore not very motivated to explore other new methods for infection protection outside of clinical trials. That said, there is a very inexpensive technology called the Alkantis that we’re trying out right now. It is a sterile cold pack that can be placed directly on the skin over the device incision, and it remains cold for about three hours. We know that the incidence of hematoma formation is intricately related to an increased risk of infection, and as I said earlier, we have a lot of patients that are on antiplatelet and anticoagulation therapy now. We just started a short trial of this technology in our laboratory among patients on anticoagulants. Although we cannot say for sure, we think that we’ve seen less bleeding and ecchymosis, and in the long run this might lower the risk of hematoma and infection. 

Thanks Dr. Simons! 

Disclosure: Dr. Simons has no conflicts of interest to report regarding the content herein. Dr. Simons also reports research support outside the submitted work, as well as having served on a Clinical Events Committee for studies of the product.