“The ESC Congress is actually the largest cardiology congress worldwide… bringing together approximately 32,000 attendees”
The ESC Congress 2025 (29 August -1 September 2025) in Madrid, Spain once again confirmed its status as the world’s largest cardiology meeting, bringing together tens of thousands of clinicians and researchers to discuss the latest advances in cardiovascular care. Among the most dynamic fields on display was cardiac implantable electronic devices (CIEDs), an area where new data are rapidly reshaping approaches to pacing and resynchronization therapy.
To help make sense of the most impactful late-breaking trials in this space, we spoke with Dr Haran Burri, head of the Cardiac Pacing and Electrophysiology Unit at the University Hospital of Geneva, Geneva, Switzerland. A leading expert in device therapy, president-elect of the European Heart Rhythm Association (EHRA) and an esteemed member of our editorial board, Dr Burri shares his insights on the highlights from this year’s congress and what they might mean for the future of patient care.
Q. What are your thoughts on this years’ ESC Congress and which late-breaking trials in cardiac implantable electronic devices stand out to you as the most impactful?
The ESC Congress is actually the largest cardiology congress worldwide. As of today, we have approximately 28,000 attendees on-site and 4,000 online. So this is a really big event and a very important one for the European Society of Cardiology.
I was at the late breakers yesterday [Friday 29th August 2025] on device therapy, and there were three trials, focusing on cardiac resynchronization therapy or conduction system pacing (CSP), which I thought were really interesting.
The first was TREEBEARD (ClinicalTrials.gov identifier: NCT06324682) that was presented by Matteo Bertini from Italy and actually published online simultaneously in Europace.1,2 This is an interesting design of a trial, devised from a prospective registry from which the investigators actually randomized patients retrospectively. Patients who had a pacing indication who were younger than 65 years of age; there were 344 of these patients, half of whom had received left bundle branch aero pacing and the other half, conventional right ventricular pacing.
The primary endpoint was heart failure hospitalization and cardiovascular death at 2 years, and left bundle branch aero pacing came out to be superior, with fewer events, largely driven by heart failure hospitalization, with a number needed-to-treat of only 15. This is yet another trial that provides data, which, I think will ultimately show that conventional right ventricular pacing is going to be replaced by CSP.
The second one was PhysioSync-HF (ClinicalTrials.gov identifier: NCT05572736).3,4 This was a trial from Brazil presented by Dr Zimmerman in patients who had a CRT indication. It was a noninferiority trial in 173 patients who were randomized to either CSP or by ventricular pacing. There was a hierarchical endpoint, so a win ratio analysis of death, heart failure hospitalization or change in left ventricular ejection fraction. In fact, very surprisingly, the trial came out with biventricular pacing (BIVP) being superior, and this is somewhat contrary to previous trials that showed that CSP was just as good, if not better, than BIVP.
If we dig a little bit deeper, one realizes that, in fact, this wasn’t truly a study on CSP, because about 1 in 5 of the patients received deep septal pacing, which was acceptable as per the design of the trial, but which may have been detrimental for the patients.
Secondly, we don’t really know how those patients really maintained CSP over time because there were no data on the follow-up on the ECGs. I suspect that a good number of those patients actually had micro dislodgements and were no longer receiving CSP, especially as all the leads were stylet-driven, which are known to be a bit more prone to dislodgments than lumenless leads.
Also, many of the implanters seemed to have been at the beginning of their learning curve, so the implantation technique may perhaps have been sub-optimal. Putting all of this together, this is a really important trial because it shows that attention to detail in implanting these CSP leads is very important.
The last trial was CAAN-AF presented by Prash Sanders from Australia (ClinicalTrials.gov identifier: NCT01522898).5,6 This was a trial in patients who are eligible for a biventricular defibrillator with permanent AFib (atrial fibrillation). The trial randomized pharmacological rate control to AV (atrioventricular) node ablation.
The trial was stopped early for futility after only 143 patients were included because there was no difference in any of the clinical endpoints.
Currently, the ESC guidelines advise us to perform AV node ablation if the percentage of biventricular pacing is less than 90–95%. In the pharmacological rate control group, it was on average 89%, which seemed to be just as good as if you were to perform AV nodal ablation and get close to 100% pacing. This trial will probably make us soften the guidelines in the future as to the percentage of biventricular pacing we should aim for before ablating the AV node.
And that’s just from day one, so still lots to come!
Q. What do you most look forward to at ESC?
Coming to congress is not only learning about late breakers and what’s new in science; it is also about ; meeting up with colleagues and friends and sharing a great experience. It is energizing and this is why I think that in-person congresses are here to stay!
References
- ClinicalTrials.gov. ConTempoRary Cardiac Stimulation in Clinical practicE: lEft, BivEntriculAr, Right, and conDuction System Pacing (TREEBEARD); ClinicalTrials.gov identifier: NCT06324682. Available at: https://clinicaltrials.gov/study/NCT06324682 (accessed 2 September 2025).
- Bertini M, Canovi L, Vitali F, et al. Two-year outcomes of left bundle branch area pacing versus traditional right ventricular pacing in middle-aged adults: a registry-based trial. EP Europace. 2025;27:euaf181. DOI: 10.1093/europace/euaf181
- Zimerman A. PhysioSync-HF: Conduction system vs. biventricular pacing for cardiac resynchronization in heart failure with reduced ejection fraction. Presented at ESC Congress 2025 Madrid, Spain, 29 August 2025. Available at: https://esc365.escardio.org/presentation/312427 (accessed 2 September 2025).
- ClinicalTrials.gov. Conduction System Pacing Versus Biventricular Resynchronization in Patients With Chronic Heart Failure (PhysioSync-HF); ClinicalTrials.gov identifier: NCT05572736. Available at: https://clinicaltrials.gov/study/NCT05572736 (accessed 2 September 2025).
- Sanders P. CAAN-AF: Cardiac Resynchronization Therapy and AV Node Ablation in Heart Failure with Reduced Ejection Fraction and Atrial Fibrillation. Presented at ESC Congress 2025 Madrid, Spain, 29 August 2025. Available at: https://esc365.escardio.org/presentation/312428 (accessed 2 September 2025).
- ClinicalTrials.gov. Cardiac Resynchronisation Therapy and AV Nodal Ablation Trial in Atrial Fibrillation Patients (CAAN-AF) (CAAN-AF); ClinicalTrials.gov identifier: NCT01522898. Available at: https://www.clinicaltrials.gov/study/NCT01522898 (accessed 2 September 2025).
Disclosure: Haran Burri is President-Elect of the European Heart Rhythm Association of the European Society of Cardiology.
Cite: #ESC2025: Dr Haran Burri on the late-breaking trials in cardiac implantable electronic devices. touchCARDIO. September 9, 2025.
Interviewer: Caroline Markham, Head of Strategic Partnerships
Editor: Heather Hall, Managing Editor
This content has been developed independently by Touch Medical Media for touchCARDIO. It is not affiliated with the European Society of Cardiology (ESC). Views expressed are the speaker’s own and do not necessarily reflect the views of Touch Medical Media.
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