PFA Everything

Not only did I attend the six late-breaking clinical trials related to pulse field ablation (PFA), but I also arrived a day early for the PFA Live Case Summit. After four days of nonstop PFA exposure, the message became clear: instead of asking what can we ablate with PFA, we should instead be asking what can't we ablate with PFA. Highlights of the PFA-related late-breaking clinical trials include:

• In a one-year follow up comparison of persistent atrial fibrillation (AFib) patients who underwent ablation with either the Sphere-9 Affera PFA system (Medtronic; n=212 patients) or with the Thermocol STSF radiofrequency system (Biosense-Webster; n=208 patients), the PFA system demonstrated noninferiority in efficacy and safety, but superiority in energy application time (7.1 vs. 17.9 minutes), treatment time (46.7 vs. 73.5 minutes) and skin-to-skin procedure time (100.9 vs. 126.1 min).
• The FARADISE global registry evaluated 1,173 AFib patients (65% paroxysmal) who underwent ablation with the Farapulse PFA system (Boston Scientific). General anesthesia and 3D mapping were performed in 59% and 15% of cases, respectively. Average skin-to-skin procedure time was 51 minutes for pulmonary vein isolation (PVI) and 68 minutes in PVI+, with decreasing procedure times observed in operators with more procedural experience. Acute device- or procedure-related safety adverse events occurred in 4.0% of cases, including four cases of hemolysis in persistent AFib patients who underwent >60 ablations of PFA. There were no deaths, coronary spasm, persistent phrenic nerve palsy, atrio-esophageal fistula, PV stenosis or esophageal lesions.
• The U.S. multicenter admIRE study evaluated 277 paroxysmal AFib patients who underwent PVI (or greater) ablation with the Varipulse PFA system (Biosense-Webster). At one-year follow-up, 76.2% were free of AFib, atrial tachycardia (AT) and atrial flutter (AFL) and 2.9% experienced a primary adverse event. The most common adverse event was cardiac tamponade (three of eight cases).
• The first-in-human PULSE-EU trial evaluated 48 AFib patients (48% paroxysmal) who underwent PVI (or greater) ablation with the Globe spherical PFA catheter (Kardium, Inc.). At one-year follow-up, the estimated freedom from AF/AT/AFL was 84.2% in the paroxysmal group and 80.0% in the persistent group. The only complication was drug-responsive pericarditis. The authors noted procedure efficiency with transpired ablation time was 27.1 minutes, LA catheter dwell time was 53.9 minutes and procedure time 87.8 minutes.
• A subanalysis of the ADVENT trial compared paroxysmal AFib patients who underwent ablation with either the Farapulse system (n=299) or thermal ablation (RF or cryo, n=294). At one-year follow-up, a significantly greater reduction to <0.1% atrial arrhythmia (AA) burden was seen with PFA compared to thermal ablation (odds ratio [OR], 1.5; p=0.04). An AA burden <0.1% was associated with a significantly improved quality of life and reduction in clinical intervention.
• A subanalysis of the MANIFEST-PF registry compared AFib patients with no heart failure (HF) (n=1,174), HF with preserved ejection fraction (HFpEF) (n=87, LVEF >50%) or HF with reduced ejection fraction (HFrEF) (n=120, LVEF<50%). At one-year follow-up, freedom from AA was significantly higher in the no-HF group compared to the HFpEF and HFrEF groups (79.9% vs. 71.3% vs. 67.5%; p<0.001) but similar between the HFrEF and HFpEF groups (p=0.26). There was no significant difference in safety events between the three groups (1.9% vs. 0% vs. 3.4%; p=0.21).

RF Ablation Remains a Proven Strategy

Although PFA trials dominated the headlines at Heart Rhytm 2024, two radiofrequency ablation studies served as a reminder that existing ablation technologies still hold value.

The real-world REAL-AF registry of 2,470 patients with paroxysmal AFib who underwent PVI (or greater) ablation with contemporary ablation techniques (including high power, short duration, ablation index and intracardiac echocardiography) demonstrated a one-year freedom from AA of 81.6% with 89.7% of patients off antiarrhythmic drugs! The complication rate was 1.9%. Average procedural time was 95.4 minutes and fluoroscopy time was 1.7 minutes. Of note, these procedures were performed by 79 experienced operators and only with the Biosense radiofrequency ablation system, so the generalizability of these outcomes may be limited.

CASA-AF was a randomized controlled trial that allocated UK patients with longstanding persistent AFib to either surgical thoracoscopic ablation (n=47 who underwent PVI, posterior wall isolation with roof and floor line and GP ablation) or radiofrequency catheter ablation (n=57 who underwent PVI, posterior wall isolation with roof and floor line, lateral mitral isthmus line, and cavotricuspid isthmus line). All patients underwent loop recorder implant as well. At three-year follow up, there was no significant difference between groups in freedom from AA ≥30 s (13% vs. 12%; p=0.49), reduction in AA burden ≥75% (58% vs. 61%; p=0.52), and quality of life scores. However, mean estimated costs were higher for patients who underwent surgical thoracoscopic ablation (£24,682 vs. £18,002).

CIEDs Iteratively Improve

Not surprisingly, conduction system pacing and leadless pacing remained the hottest areas of investigation for cardiac implantable electronic devices (CIEDs).

Conduction System Pacing
The LEADR trial evaluated 643 patients who were implanted with a lumenless 4.7Fr catheter-delivered righ ventricular ICD lead modeled after the SelectSecure SureScan MRI Model 3830 pacing lead (Medtronic). At 12-month follow-up, freedom from lead-related major complications was 97.1%. Defibrillation testing was successful in 97.5% of patients. Targeted conduction system pacing with this lead will be evaluated in an upcoming trial.

The TECSPAM study evaluated 341 patients who underwent extraction of conduction system pacing leads (224 His-bundle leads, 117 left bundle branch area pacing (LBBAP) leads, average lead dwell time 22 months). Complete procedure success occurred in 99% of cases while 1% had retained fragments. Extraction was achieved with manual traction (91%), mechanical tools (8%), laser (2%) and femoral tools (1%). Complications occurred in four patients (1.3%): transient complete heart block (n=1), severe TR (n=1) and dislodgement of other leads (n=2).

The BIO-CONDUCT study evaluated 267 patients who underwent LBBAP with a stylet drive, retractable helix lead (Biotronik). At three-month follow up, freedom from device- or procedure-related serious adverse events was 98% and implant success was 95.7%.

Leadless Pacing
At one-year follow-up in 300 patients who underwent a dual-chamber leadless pacemaker system (Aveir DR, Abbott Medical), the primary safety endpoint (freedom from device- or-procedure-related serious adverse events) was 88.6% and the primary efficacy endpoint (atrial captures threshold ≤3.0 V at 0.4 ms and atrial sensing ≥1.0 mV) was 92.8%. These metrics were consistent with previously reported three-month outcomes.

The MODULAR ATP trial reported interim outcomes on 162 patients who underwent combined subcutaneous ICD and leadless pacemaker implant (EMBLEM S-ICD and EMPOWER LP, Boston Scientific), which allowed for wireless communication between the two devices that provided ATP. At six-month follow-up, the major complication-free rate was 97.5%, wireless communication success rate was 98.8%, and pacing capture threshold success rate(≤2.0 V at 0.4 ms) was 97.4%.

AI Shows Promise for EPs

The meeting kicked off with Jagmeet Singh, MD, PhD, FACC, providing an inspiring keynote on the potential for artificial intelligence (AI) to shape the future of electrophysiology (EP). This sentiment was reinforced by the TAILORED-AF trial which randomized persistent or longstanding persistent AFib patients to radiofrequency ablation with PVI and targeted ablation guided by AI-detected spatiotemporal dispersion (Volta Medical; n=187) or to PVI alone (n=183). Those who underwent AI-guided ablation experienced a significantly higher acute AFib termination rate (66% vs. 15%; p<0.001) and 12-month freedom from AFib (88% vs. 70%; p<0.001). There was no significant difference in adverse events between groups. However, the AI-guided ablation nearly doubled the total procedure time (178 vs. 92 minutes; p<0.001). The mechanism of this AI algorithm remains poorly understood.

Learn the Business of EP

After experiencing consecutive years of embarrassing reimbursement cuts in procedural services, EPs have now taken it upon themselves to advocate for change. The meeting featured a series of sessions on the Business of EP, predominantly led by the cohort of private practice EPs, which include current HRS president Jodie Hurwitz, MD, FACC. Discussions included productivity, payment and relative value units, and debates were held regarding more controversial topics such as performing ablations in ambulatory surgical centers. The bottom line is that EPs need representation on decisions that affect the financial well-being because "if you're not at the table, then you're on the menu."