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Monthly clinical deep analysis in cardiac electrophysiology: AF, VT, SVT, ablation, devices, antiarrhythmic drugs, and high-impact trials. The Signal: physician-level analysis that identifies what matters in EP and translates evidence into clinical practice.
EP Edge™: The Signal is the flagship monthly podcast from EP Edge, delivering structured, expert-level interpretation for electrophysiologists, cardiologists, fellows, and clinically engaged practitioners. Each episode goes beyond summaries to integrate evidence across trials, guidelines, mechanisms, and real-world practice.
Episodes cover the full spectrum of electrophysiology, including atrial and ventricular arrhythmias, supraventricular tachycardias, antiarrhythmic pharmacology, pacing and defibrillator strategies, mapping and ablation technologies (including pulsed field ablation), and emerging data shaping clinical decision-making. This is not a news recap—it is a curated synthesis focused on what truly changes practice.
Content combines mechanistic insight, cross-trial evidence review, critical appraisal of methodology and outcomes, and practical application in the EP lab and clinic.
EP Edge™: The Signal complements the weekly EP Edge™: Journal Watch by providing deeper analysis and clinical synthesis. For patient-focused education, explore EP Edge™: Heart Talk.
Available as both podcast and newsletter via EP Edge on LinkedIn and Substack: https://epedge.substack.com/
Welcome to the EP Edge October 2025 Issue five. This is Doctor. Sharma. Before we roll into the AI conversational segment, let s set the stage. We have come a long way in cardiac pacing from right ventricular pacing to cardiac resynchronization therapy and now to conduction system pacing.
Dr Niraj Sharma:It all began with RV pacing. Life saving, yes, but not physiologic. Over time we learned that when RV pacing burden gets high, especially above 40%, it drives dyssynchrony and adverse remodeling. Two early signals really shaped this story. In 2002, the DAVID trial showed worse outcomes with more RV pacing, and in 2003, most trials confirmed patients with more than 40% pacing had higher heart failure events.
Dr Niraj Sharma:Mechanistically, it's about a wide paced QRS, an apical activation sequence and the underlying substrate. Clinically, pacing induced cardiomyopathy shows up in about ten-twenty percent of patients over time. Meta analyses peg it around twelve percent, with contemporary cohorts showing six-twenty percent within ten years. Who's at risk? Wider paced QRS, higher RV pacing percentage, lower baseline LVEF, male sex, intrinsic conduction disease, and apical lead position.
Dr Niraj Sharma:To counter this dyssynchrony, we moved to biventricular pacing It can be transformative. But here s the catch: non response rates hover around thirty-forty percent. Why does CRT fail? Suboptimal LV lead location, scar burden, non left bundle branch block patterns, AF timing issues, and challenging venous anatomy. A great therapy but not universally physiologic.
Dr Niraj Sharma:That's what pushed us to conduction system pacing, His bundle first and now left bundle branch area pacing. The idea: recruit the native His Purkinje system and restore physiologic activation. Is it perfect? No. Implant.
Dr Niraj Sharma:Success for left bundle area pacing is around ninety percent overall, meaning about ten percent failure, and in heart failure populations, that number climbs closer to eighteen percent. Larger LV size, broader QRS, and structural heart disease make it tougher. And while threshold rise or loss of capture is uncommon, it's not zero. So here's where we stand. We know why RV pacing matters, especially past that forty percent threshold.
Dr Niraj Sharma:We know why CRT sometimes falls short. And we now have CSP, which aims to bring us closer to true physiologic pacing while acknowledging its limitations. With that foundation set, let's jump into today's EP EDGE discussion. This is an AI conversational narration of the EP EDGE October newsletter and as always it has been personally vetted for accuracy.
AI 1:Welcome to the deep dive. Today, we're looking at sources pointing to a, well, a pretty big change in managing heart rhythms. It's all about left bundle branch area pacing, LBBP. Seems like it's really starting to outperform the older methods, like biventricular pacing or BVP. So our goal today is to kinda unpack why LBBP is gaining ground and, also look at the hurdles that still exist.
AI 2:Yeah. Absolutely. The core idea really is this move towards what's called physiologic pacing.
AI 1:Mhmm.
AI 2:You could think of BVP, the older method, like taking a detour around road construction. It works, but it's not ideal. LBBBDP though, it aims to use the heart's own electrical highway, the His Purkinje system.
AI 1:A natural wiring.
AI 2:Exactly. So you get much better electrical synchrony. The timing is just more natural and the clinical results, well, they really back that up.
AI 1:Okay. Okay. So if it uses the natural pathways better, why wasn't this the go to method all along? Why did we stick with BVP for so long?
AI 2:Well, mainly it was technical challenges. Getting the lead in the right spot is tricky, but the data piling up now is just so compelling. You know, it makes tackling that learning curve really worthwhile. I mean, look at the clinical outcomes, especially serious arrhythmias. It's quite dramatic.
AI 1:Okay. Let's dive into that. What kind of numbers are we seeing?
AI 2:So the ICLAS data, for example Right. It showed sustained VTVFs. These are dangerous life threatening rhythms. The rate dropped way down
AI 1:How far down?
AI 2:To about four point two percent with LBBF. Yeah. Compare that to nine point three percent with BVP.
AI 1:Wow. That's that's less than half. Significant.
AI 2:It really is. And it's not just VTVF. We also see a drop in new onset atrial fibrillation, which can be really problematic.
AI 1:Right. AFib. What were the numbers there?
AI 2:About two point eight percent for LBBP versus six point six percent for BVP. Again, a substantial difference. It's And not just about preventing bad rhythms, the mechanics look better too based on measurements.
AI 1:Like the QRS duration.
AI 2:Exactly. We see a narrower QRS duration. And for you listening, the QRS is basically the electrical footprint of the ventricles firing. Narrower means they're firing much more closely together in time. Better synchrony.
AI 1:Which leads to better pumping function presumably.
AI 2:Precisely. Better reverse remodeling of the heart and yet significant improvement in left ventricular ejection fraction or LVEF.
AI 1:And maybe one of the biggest selling points isn't just the good thing that LBBA does, but also the bad thing it avoids. You mentioned the risk with standard RV pacing earlier.
AI 2:Yes. The risk of pacing induced cardiomyopathy, PICM. That's a real concern. Standard right ventricular pacing, just pacing the RV can cause this chronic, unnatural activation pattern and maybe up to like twenty five percent of patients could develop heart muscle weakness, cardiomyopathy because of it.
AI 1:A quarter of patients. That's not insignificant.
AI 2:Not at all. So LBBAP, by trying to preserve that natural activation pathway, it seems to really lower this PICM risk Yeah. Which, you know, translates to better long term outcomes, especially for heart failure patients.
AI 1:Okay. Now this next bit from the sources, this felt like a real moment. The outcomes based on patient sex.
AI 2:Oh, absolutely. This is something that really should shape how we approach patient selection moving forward, specifically women who have non ischemic cardiomyopathy, so not caused by blockages and left bundle branch block. They seem to get an incredibly strong benefit from LBBP.
AI 1:How strong are we talking?
AI 2:The data pointed to a thirty six percent lower risk for the combined outcome of, death or heart failure hospitalization in this specific group.
AI 1:Thirty six percent lower risk overall. But wasn't there an even more striking number for just hospitalizations?
AI 2:Yes. That's right. For heart failure hospitalizations alone, a sixty percent reduction.
AI 1:Sixty percent. Wow. For that group, LBB isn't just an option. It sounds like it should be the first option, the primary strategy.
AI 2:You could certainly make that argument based on this data. It really highlights the importance of tailoring the therapy. But you know, while the physiology is superior, we do need to be realistic about the challenges. LBBAP isn't foolproof.
AI 1:Right. The real world application. As more centers adopt it, we're seeing some procedural issues pop up.
AI 2:Exactly. It's a technically demanding procedure. You're guiding a lead quite precisely through the septum, that wall between the ventricles. And the sources do flag some worrying complication rates during this, rapid adoption phase.
AI 1:Like what?
AI 2:Things like worsening tricuspid regurgitation, leakiness of the tricuspid valve reported in, well, up to maybe thirty two percent in some series and, more concerning perhaps septal perforation actually going through the wall in up to fourteen percent.
AI 1:Okay. Those numbers are concerning. Why are these happening? Is it just technique?
AI 2:It's partly technique, yes, but also the anatomy itself. The septum isn't uniform. It can be fibrous, scarred, complex. So actually failing to capture the conduction system effectively, that can happen in maybe ten-fifteen percent of cases, especially with difficult anatomy. Success really depends on careful technique and choosing the right patients.
AI 1:So putting it all together, where does this leave us? LBB is clearly moving from just an alternative towards being a primary strategy, but overcoming these technical issues is key.
AI 2:That's the crux of it. The future really depends on, integrating better tools like using advanced imaging during the procedure maybe combined with EP mapping to really confirm you're in the perfect spot that could reduce complications like perforation.
AI 1:And the leads themselves.
AI 2:That's the other big piece. We need innovation in the lead technology. Leads that are robust enough to handle being placed in this very specific mechanically active location long term without failing.
AI 1:So to wrap up, the sources are clear. LBB UP offers some really compelling physiological advantages, reducing dangerous rhythms, potentially avoiding PICM. But
AI 2:But success hinges on mastering the technique and importantly on improving the technology to minimize those mechanical and procedural complications.
AI 1:It really comes down to that interface between technology and biology.
AI 2:It does. Good. Maybe the thought to leave you which is this. We're asking a sophisticated piece of hardware, a pacing lead to maintain perfect electrical contact within a specific tiny area inside the heart muscle. A muscle that's constantly moving, contracting for potentially decades.
AI 2:Can our currently designs truly withstand that kind of long term mechanical stress in that precise location? That's the engineering challenge we absolutely have to solve to make LBPP the durable go to standard for everyone who needs it.
Dr Niraj Sharma:And that wraps up today's discussion on left bundle branch area pacing. As we've seen, bundle area pacing has evolved from an exciting concept to a reliable pacing strategy that's changing how we approach physiologic pacing. It's not the finish line, but it's a major step forward. If you'd like to dive deeper into the data, references, and infographics, you will find it all in the full EP EDGE October 2025 newsletter on LinkedIn. Thank you for listening.
Dr Niraj Sharma:This is Doctor. Neeraj Sharma signing off. Now. I will see you in the next episode of EPH. Bye for now.