Hi, I'm Eric Prystowski and welcome to another segment of EP on EP. This is an absolutely wonderful session for me because of the man that I'm interviewing today, Dr. George Klein, who is a professor of medicine at Western University, but George and I started our careers together at Duke back in the late 70s and have been friends ever since and authored books together. And since we're talking about Duke, George, let's get right to the topic. What I want you to talk to me about today and to the audience is this whole concept of risk stratification for sudden death in patients with asymptomatic pre-excitation. So why don't we start at the beginning in the wonderful landmark paper you wrote when you were at Duke on risk stratification. Why don't you start with that? Well, it was a very interesting time. That's where it all started, but you remember in the old days at Duke, they used to wheel in a WPW patient every week with ventricular fibrillation from somewhere in the world. And it was a mecca for WPW. And they had a large database now of people who died and who didn't die and so on. So I was asked to write that up, which I did. The bottom line for that study was that the risk of death really depended on the rapidity of the ventricular rate during atrial fibrillation. And this was at a baseline rate. So all our patients at the time, as you recall, were supine but non-sedated. We didn't do sedation. So relatively heightened adrenergic state, but not nuts. So all the data are based on that, not on isoproteinol or nothing like that. And the bottom line was that if the shortest RR interval during pre-excited atrial fibrillation was less than 220 is the real one, where the sudden deaths clustered between really 180 and 220, there was one outlier at 240 or 250. I remember, because I always remember your graph, yeah. And we looked at that outlier and I couldn't exclude them, but there's something fishy about it. But nonetheless, it is what it is. And we set the number at 250. But the real number of risk is probably in the range of 300 beats per minute or 200 to 20. Okay. So I think that that has stood the test of time. In other words, if you don't achieve those rapid rates, you're not at risk. But if you do achieve those rates, you are at risk, even though it's not high, not as high as you might think. So with that as a starting point, and I would agree with you, I've read the literature on up from your paper and I have yet to find anything that is better than your number. Having said that, there's been an ongoing debate and different people jumping in and out of it of how we should approach the patient with asymptomatic WPW, or I should say symptomatic pre-excitation. And I'd like you to talk about that in two different ways. Number one, you were pretty hard, well, everyone was pretty hardcore because the only therapy other than drugs was surgery, not ablation. So ablation now is an easier path if you're competent, right? So I was going to ask you, does that change your mindset that we have to be sort of hardcore? And second of all, should we be searching populations who are asymptomatic to find out more about them? Those are two very important questions and they're really very distinct because whether to ablate or not is one issue, but if you're going to do the ablation, the method of ablation does have some bearing. It lowers our threshold, undoubtedly lowers our threshold, but you still want someone to be at reasonable risk. And what does that mean to me? Well, it means at a baseline study, if they're not getting down to below the 250 range at a baseline study, they're not at risk. There's no evidence in literature to support that whatsoever. Now let's say they are in the range, maybe 250 or less, or certainly in the 200 range, then they are at risk, but still relatively low. We did a natural history study years ago and it turns out that maybe a third of the population of asymptomatic WPW had rates in that range at rest, and yet most of them do fine, thank you. So it's sporadic, the death rate is still very sporadic. So even though you are in the at-risk group, your risk is still relatively not very high. So I don't think anything else helps us a lot. If you want to pour in isoproteinol, you will achieve that in almost everybody, and if you want to ablate everybody, then you pour in some isoproteinol. In fact, you published that, I remember your study, yeah. You've got something that's already relatively nonspecific and you're making it totally nonspecific. So that's fine. To me, if you're in the at-risk group, and that's defined by rates and atrial fibulae, they don't die from other things, as you know, it's VF, then the question is, should you get it fixed? And I think that the key thing is having people to talk to that you can explain the situation. What frightens you more? Is it the notion of dropping dead sometime in the next 20 or 30 years? Well, the risk of that's probably pretty low, but maybe 1 in 1,000, but if it's you, you're worried about that. Or are you worried more about a procedural risk, so that people have to weigh that? So I offer those people an ablation, but I try to make very clear the relative risk of an intervention versus non-intervention, and I come back from the viewpoint of a place that's done a lot of WPW, and I trust all of my troops who now do that, and we've seen a lot of WPW. So that's also an important factor, is should you do it? And if you do it, do enough of them that you can do it competently. And that's a key point nowadays. I do a lot of teaching, as you know, with fellows and chat with them a lot, young folks coming out, and they're doing lots of AFib ablation and lots of VT ablation and PBC ablation, and we sort of dig down how many WPWs you're doing, I've done 10 or 20 in two years. Now you and I both know that's not enough to tackle a complex WPW, and especially something that's in the septum, where they can really get into trouble, right? So I think we would both agree that if you're going to get into this business and offer a therapy like ablation, you should very well have your ablation skills down pat, right? And that goes for many things in medicine, but especially things that are operator-dependent, and as you well know, or anybody in a secondary or tertiary centre knows, they still get a lot of complications from WPW ablation, and it's always a shame to see a young kid with AV block or something, because somebody didn't quite see something during a routine study for a septal pathway. So let it be said that first you have to be at risk, and then if you are in the at-risk group, you need a nice conversation pointing out to people, well what are you afraid of? Are you afraid I'm going to give you an AV block, or are you afraid of dropping dead? And you well know that there are people who will choose one way or another. So one last thing, there is also this discussion out there that age matters, so do you, if you have two people come to you George, one is a 54-year-old person who had it picked up on a routine ECG in a doc's office, never had a symptom, and the other is a 14-year-old boy who had it picked up. I must admit I'm a little more aggressive with the 14-year-old boy, I don't know that I should be, but there is that feeling out there, right? That's intuitively obvious, isn't it, I mean because it's very uncommon to get a sudden death from WPW generally after the age of 40, not zero, so you certainly have the same discussion with them, but tilted a little more in that regard, whereas if you're 14 you've got a long way to go, and I would say that you're, and it would be catastrophic if you miss something. So I think my best asset is having reasonable people to deal with, that I can explain the issues. I don't like the ones that say, well what would you do doctor, and it puts the whole burden right on you when you're trying to paint the picture of really equipoise, depending on your personal preference, and they're saying, they're throwing it back in your court. So it's been a great discussion, I think that you led the way with your really fine paper back in the day, it's been great being your buddy for all these years, I hope we have a lot more years to laugh through it, George. Thanks Eric. Alright, take care.

risk stratification

sudden death

asymptomatic pre-excitation

ventricular rate

ablation procedures