Early Insights With a Novel Mapping and Ablation System: Interview With Brett Atwater, MD

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EP LAB DIGEST. 2025;25(4):1,20-23.

Interview by Jodie Elrod

EP Lab Digest speaks with Brett Atwater, MD, from Inova Medical Group in Virginia, about his experience with the Affera mapping and ablation system (Medtronic), including his workflows with the system, observed patient experience, and what he most looks forward to in the future of EP.

Can you describe the cardiac electrophysiology (EP) program at Inova Health System? As a leading research hospital and a high-volume center treating over 1500 atrial fibrillation (AF) patients annually, what sets Inova apart in terms of patient care, innovation, and research in EP?

I believe what sets us apart is our focus on adoption of new technologies. We have several recent examples of that. Bachmann’s bundle pacing has gained a lot of interest by our team as a means to reduce AF burden in patients with bradycardia indications and potentially as a stand-alone therapy for treatment of AF. For AF ablation, we are focused on bringing in new technologies that can help improve the safety, efficacy, and efficiency of our procedures, including the recent addition of the Affera Mapping System (Medtronic).

What excites you most about the mapping capabilities of Affera?

One of the exciting things that we have experienced so far with the Affera system is the capability to map and ablate off a single catheter and quickly generate maps with multiple electrodes. Being able to ablate off the same catheter also

allows for a very efficient workflow because you do not have to do any sheath exchanges to replace your ablation catheter with a multipolar mapping catheter—it is all built into the same platform. That makes for a more effective case since you can immediately ablate the site of an interesting electrogram without having to readjust a catheter or move a different catheter to that location. By combining the ability to create a high-density map with the ability to deliver a very effective ablation lesion, we have observed improvements in both efficiency and efficacy. 

Another great feature that we have noticed about the Affera system is that patients experience very little pericarditis after their ablation procedures, and we think that is a result of pulsed field ablation (PFA). The particular sequence that Affera uses for PFA seems to produce pericarditis-type symptoms such as chest pain or shortness of breath less commonly than radiofrequency (RF) ablation. Our patients are no longer calling in the first couple of days after the procedure with complaints of chest pain or shortness of breath. That frees up a lot of time for our clinic staff and we have seen fewer patient visits to the emergency department and fewer cardioversions within a month of the ablation procedure as well. So, that has been a positive change compared to our previous experience with RF ablation.

Can you describe the workflows that you have developed with Affera? 

We started using the Affera system about 8 weeks ago, so we are still working on developing these workflows. We have done a total of about 120 cases during that time. Because of the requirement to have the patient fully anticoagulated with heparin prior to the introduction of the Sphere-9 catheter, we realized early on that it was important to go ahead and start heparin very early in the procedure. Rather than waiting until we have access, we are now giving our heparin bolus before we start getting access, immediately after the patient is intubated. That allows time for the activated clotting time (ACT) to climb to the correct level by the time we want to introduce the catheter. So, our current workflow is that the patient is intubated and sedated for general anesthesia, and as soon as that is done, they get a heparin bolus, then we drape the patient, get access, and are ready for transseptal. We check the ACT as we are preparing for transseptal to make sure that we have reached our target of 350 to 400 before the catheter is inserted. That allows for a much more efficient process than waiting to give heparin until we are ready to go transseptal or even after transseptal, which had been our workflow with RF ablation.

Can you describe the Sphere-9 catheter handling?

It handles beautifully, much like our previous RF ablation platforms. The responsiveness of the bidirectional mechanism feels a lot like what we are used to with catheters produced by competitors. It has a brake on it, which allows the operator to hold the curve in place. It is also very responsive to both torque and deflection. Because the handling is so good and the lesions are so effective, we are now performing a greater percentage of our AF cases without a deflectable sheath, saving cost for the procedure.

What benefits of PFA do you see as most valuable to you and your patients, in terms of safety and efficiency?

In terms of efficiency, the 4-second lesions and the ability of the pulsed field generator from Affera to be able to come back on immediately without having to do any charging has been beneficial. We can repeatedly ablate and move very rapidly without having to wait between delivery of those lesions. As mentioned, it also does not seem to be causing as much pericarditis as RF ablation. It allows you to safely ablate posteriorly or anteriorly in the atrium. That flexibility with the system allows us the ability to go after AF with pulmonary vein isolation as well as focal atrial tachycardias and atrial flutters in the left atrium (LA). 

We really challenged the system in the first 8 weeks. We had a series of patients who had experienced mitral annular flutter after prior AF ablation using RF energy. In several of these cases, we had performed a second procedure using RF and even vein of Marshall ethanol infusion to try to eliminate the atypical atrial flutter without success. We have successfully completed a total of more than 10 prior failed mitral flutter ablations with the Affera system in the first 8 weeks we have had it. We have observed first pass termination with bidirectional block in almost every case, without the need to ablate epicardially in the coronary sinus. This is remarkable given that these patients had failed multiple prior attempts, in some cases using both ethanol injection and endocardial and epicardial RF ablation.

Regarding the Sphere-9 catheter, when do you decide to use RF vs PFA during a case?

We follow the manufacturer’s recommendations on this when we use PFA, so this includes pretty much everywhere around the posterior portion of the left atrium, or anywhere near the esophagus or phrenic nerves. If we are going to ablate near a coronary artery, for example, the final lesion on a mitral isthmus ablation or certainly in the cavotricuspid isthmus (CTI), we use RF. We have had very good experience with that as well. Using the RF mode in the CTI, we have been able to get block with 2 or 3 lesions in most cases. So, a total of 10 or 15 seconds of ablation energy is all that is necessary to get bidirectional block, which is sustained for the 30-minute wait period.

What has the general patient experience and feedback been after Affera ablation? How do they feel post ablation? How has the conversation pre-ablation changed, if at all?

One of the patients that I performed an ablation on last week commented that compared to her prior RF ablation, it was a breeze. She felt like she did not have as much of a sensation of being “washed out” and fatigued after the procedure as she did with the prior RF ablation. Other patients have had less chest pain than they had with their prior procedures. So, I think the patient experience overall is superior to what we had experienced with the older RF platforms. This certainly changes the expectations we set for patients prior to their procedures. We formerly discussed that they may experience chest pain, shortness of breath, or fatigue after the procedure as a result of inflammation. We no longer expect to see that, so we no longer need to prepare the patient for post-procedure symptoms.

How did your hospital administration react to the acquisition of another mapping system? What helped convince them to purchase another system?

We actually acquired the first system through a generous gift from a grateful patient. Based on the results of the SPHERE Per-AF trial, we believed the Affera mapping system and Sphere-9 catheter would allow us to achieve his goals of providing access to a new technology that could improve outcomes for our patients. After acquiring the system, we performed a comparative analysis of the Sphere-9 catheter, 2 competing FDA-approved PFA catheters, the cryoballoon, and RF ablation catheters from 2 manufacturers that are capable of delivering high-power short-duration ablation. The outcomes included assessments of patient experience (n=176 telephone interviews), frequency of recurrent AF requiring cardioversion within the 3-month blanking period, physician experience (n=8 surveys), procedure time, fluoroscopy exposure, and frequency of first-pass isolation or block across all linear ablation lesions. The results will be published separately, but convinced the administration that acquiring additional Affera mapping systems provided sufficient value to our patients, the physicians, and the health system to justify the cost of acquisition.

Where do you see future utility of Affera? What are you excited for, including future indications?

Right now, we are most excited about the use of Affera for procedures that have been particularly challenging in the past. Mitral annual flutter is a prime example of that. It is currently FDA approved for this indication and we have found that it is so much more effective and efficient at those complex ablations than what we have experienced with previous technologies. In the future, I think all of us are interested in finding out how effective and safe Affera may be for ablating premature ventricular contractions (PVC) and ventricular tachycardia. Medtronic has 2 upcoming studies looking at the safety and effectiveness of both PFA and RF ablation through the Sphere-9 catheter for treatment of those arrhythmias. We are anxious to see how it will perform in the ventricle, and there is reason to hope that it will perform as well as or better than it does in the atrium. So, for difficult cases, I think it will be a nice tool in the toolbox to be able to have an efficient and more effective procedure for complex PVC ablations. 

Disclosure: Dr Atwater has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. He reports research funding, consulting fees, payment or honoraria as a speaker for educational events, and participation on a data safety monitoring board or advisory board for Medtronic.

This content was published with support from Medtronic.

The transcripts were edited for clarity and length.