On this episode of The LEAD, we're recording live from EHRA. I'm Mike Lloyd, and today we're going to talk about an article in Cirq Arrhythmia EP published last month called Subcutaneous Implantable Defibrillators in Young Patients, Arrhythmias, Complications, and Physical Activity, first author Pietro Francia on behalf of the SICD Rhythm Detect Investigators. My two commentators today are Professor Raynaud Knops from Amsterdam University Medical Center and Dr. Karim Benali in Saint Etienne and Rennes, France, and Bordeaux. Welcome gentlemen. Thank you for commenting on this clinical paper. Professor Raynaud, let me ask you first, you said this is one of many SICD papers in the young. Tell us, what specifically are they trying to get at? What's the background? What's the rationale? Yeah, so initially when SICD started somewhere around 2009, it was used more or less for a niche patient, niche indications, post-infection, vascular access issue, but also really young patients because the durability of the lead, not having a lead in the heart, was expected to be better in that patient category. And we know from a lot of transvenous registries that younger patients more or less have more complications because they're more active, leads tend to fracture a little bit more, and some of them have more arrhythmias or certainly inappropriate therapy. So it's not a large population of patients with an ICD, but a very interesting population. And that population got targeted in the beginning with SICD quite a lot, but good research of good larger registries investigating the difference between, let's say, the more general ICD population and young ICD patients with SICD. We need that. There are a couple of mores. We'll discuss that later, but that's why I think it's important to figure out is this really an advantage for those patients, or are they just as worse off as transvenous patients with an ICD? Right. Karim, how did the investigators look at this in this cohort? So this study basically is a retrospective analysis of data that were collected prospectively in a registry including 19 Italian centers. The registry enrolled about 1,200 patients aged from 15 to 65 years and who received a subcutaneous ICD between 2013 and 2022. The SICD was only the emblem device from Boston Scientific, and in this sub-analysis of this registry, 600 patients only were included, those who completed the follow-up questionnaires. The physical activity level was evaluated using the IPAQ questionnaire, a validated tool that classifies individuals as inactive, moderately active, or highly active individuals. Additionally, a custom sports questionnaire was used to identify patients engaged in recreational sports activities. The primary endpoint of the analysis here was a composite of arrhythmia-related events and lead or device-related complications. Outcomes were compared across activity levels and between recreational athletes and non-athletes. Notably, the authors used also propensity score matching to account for baseline differences. Are you familiar with this IPAQ questionnaire? This is new to me. Have you heard of this one before? Well, not this specific questionnaire, so it's very interesting. We have a sports cardiologist on our team that also does a lot of devices, and we often discuss how difficult for a sports cardiologist is to define who is really active. And there are a lot of different questionnaires that are out there, and they are usually for other disease subtypes than for ICD patients. So it is important to at least have some additional information because usually we just don't know how active our patients are. So I think that they used a very good, not too complicated of a questionnaire to at least make a verification, is somebody not active, mildly active, or really active? And I think that those three categories, if you come to three categories, that's a win in itself already. So I don't know this specific questionnaire per se, but I do think it's really important to get some more insight in how active our patients are. It was nice that they quantified it in this way because, as you say, it's not easily done. I tend to overestimate my activity, too. Reino, what did they find in this trial? Well, in general, the good news is that they found, in contrary to what we see in transvenous ICDs, that there are more complications, lead fractures, repeated surgery in younger ICD patients, that if you compare active SICD patients versus non-active SICD patients, that there's not a difference in complication, which vouches a little bit for the whole reason why SICD has been developed to overcome lead-related complications. And it makes a lot of sense. So if that subcutaneous ICD is under your skin, but also if the lead is just sitting there on your chest, pre-sternal, it's not going to move when you, or it's going to slightly move when you're active. And so, with regard to complication, that really holds true for this younger category. I was a bit surprised with the results, a positive surprise with the results of inappropriate therapy, because I think most of us know that one of the weaknesses of SICD is sometimes the sensing algorithm during exercise, especially younger patients might get morphology changes during exercise, larger T waves, and that can quickly lead to double counting in SICD patients and inappropriate shocks. So I was a bit surprised to see that they didn't find that difference, and I think that's largely related to an algorithm that has been introduced, I think already five years ago, the SMARTPASS algorithm that's specifically designed to filter out that T wave over sensing. So I'm glad to see that all the attention that Boston Scientific has put into promoting the SMARTPASS algorithm, actually when you do a sub-analysis like this, also pays off. Were you surprised, you mentioned this sub-sternal location, were you surprised, I always worry about fractures, a baseball or a fist hitting this area, American football maybe. Yeah, so that's funny. So the design of the lead is so much different than the transvenous ICD, which has to be flexible and a bit elastic. If you do lead extractions you know that transvenous lead can come apart in a horrible way, but the SICD lead has an internal core, a solid metal core, for extra rigidity, and funny things, to show people how sturdy it is, we often lift an ICD programmer, just hang it on an SICD lead and then it weighs 10, 12 kilograms, and that lead doesn't give way to anything. So I would have expected that to be true, and from my personal experience I can say we are a referral center for genetic arrhythmias, we get a lot of young people who got resuscitated on either the soccer pitch or doing sporting activities, and we have several athletes that are really in the highest level of soccer competition, and they get body checks and tackles all the time, bumps on their ICD, and it never breaks. So I wasn't surprised that during that extreme physical activity that the SICD would have such a positive result. Kareem talk to us a little bit about the limitations of this paper. For sure, the results are extremely important for the field and highly interesting regarding the conclusion, however we still have to discuss some limitations in a round to observational studies. First, the physical activity level was self-reported, which could introduce a degree of recall bias, but for the questionnaire, the IPAC questionnaire used here seems to be a validated tool as we discussed a bit earlier. Additionally, there is a link, there is likely a degree of selection bias in this population, in the population of the study, since only patients who completed the questionnaires were included, representing only about 50% of the whole cohort of the registry. The third point to note is that possibly this result reflects also more the outcomes of long-standing SICD users, as given the method, the early post-implant complication might be under-represented. And finally, as the author notes, there could be a bias in terms of causality relationship, as lower activity level could be a surrogate for worse baseline health, and also being associated with a higher risk of arrhythmia occurrence in this population. So these authors, the take-home is, athletes, no matter how active you are, this is a good thing, not a bad thing at least. So, Reino, the Netherlands 2025, age under 50, does this reflect clinical practice in your area, and if not, would it change anything? Yeah, certainly. I do think that this reflects clinical practice. So below 50, we counsel our patients on the existence of both a transvenous and an SICD, but do emphasize that we expect most of our younger patients to have a longer lifetime ahead of them, unless they have a really terrible cardiomyopathy. But most of them have a real life, long life expectancy. And then with the respect of the data that we know from the Patoran trial, long-term data and complications, we try to tell them that over a longer period of time, just by being young, that an SICD might have benefits for them, but especially in the patients that are really active. And it's really difficult to define being active, so I really applaud them for at least trying to... Quantify it. Yeah, to quantify it, and we use that as an additional argument for patients in the counseling, if you are really active, we really support you going for an SICD. And when I look at how patients decide after being counseled in that way, I think about 80% of the patients under 50 favor it. 80%? Yeah. And obviously, we have to be honest, the SICD is a bit larger than a transvenous ICD. If you have younger female patients with low BMI, they tend to be scared a little bit by the size of the device, so sometimes the cosmetics play a part in that as well. However, if this is a younger female athlete, then usually they tend to go for SICD. Karim, what about in your region? Is this common? Is it mostly transvenous? It really depends on the centers. I don't do pacing myself, I do mainly ablation, but my colleagues in pacing, since a few years, they really try as much as possible to have this shift toward the maximum volume of implantation of transvenous, if possible, mainly in this population as we discussed earlier. But I know that still some of my colleagues in other regions have some difficulty to implement this shift in their population. So I mean, it's still an heterogeneity practice in our field. We've been discussing SICDs in the young and athletic. Our commentators today are Reino Knops and Karim Benali. Gentlemen, thank you. Thank you for having us. Thank you.

subcutaneous implantable defibrillators

young active patients

arrhythmias

complications

physical activity

young patients