Abstract
Aims
A dual-energy ablation system was developed to optimize targeted energy delivery via a flexible-tip, contact-force sensing catheter with electroanatomic mapping integration. This is the first report of long-term safety and effectiveness results of this system for ablation of paroxysmal atrial fibrillation (PAF).
Methods and results
The FOCALFLEX study is a prospective, multicentre study. Patients with PAF were enrolled between August 2024 and January 2025, with 144 patients (62.0 ± 10.0 years, 62.6% male) undergoing ablation with the TactiFlex PFA System at 21 sites worldwide. Primary safety and effectiveness endpoints were the rate of pre-defined serious adverse events within 7 days and the 6-month freedom from documented AF/AFL/AT episodes >30 s after a 90-day blanking period.
Pulmonary vein isolation (PVI) was performed in each case with pulsed field required for posterior left atrium (LA) ablation and radiofrequency (RF) for cavotricuspid isthmus or near coronary arteries. Non-PV targets and modality were at physician’s discretion. Acute effectiveness was confirmed via entrance block and post-ablation LA voltage map after a 20-min waiting period and was achieved in 99.6% (566/568) of treated PVs with 95.5 ± 37.1 pulsed field ablation (PFA) applications/patients. Procedure, fluoroscopy, LA dwell, and PV ablation times were 112.2 ± 29.5, 7.6 ± 5.7, 81.1 ± 19.7, and 47.4 ± 16.4 min, respectively. There were two (1.4%) primary safety events. At 6 months, 81.0% of subjects were free from documented arrhythmia recurrence and the protocol-defined primary effectiveness rate was 79.6%. There was one repeat ablation (0.7%) after the blanking period through 6 months.
Conclusion
The FOCALFLEX study results demonstrate safety and effectiveness of a novel dual-mode RF/PFA system through 6 months of follow-up to treat symptomatic, recurrent PAF.
Clinical trial registration
ClinicalTrials.gov Identifier: NCT06271967
Keywords: pulsed field ablation, Radiofrequency ablation, Dual energy, Pulmonary vein isolation, Focal catheter
Graphical Abstract
Graphical Abstract.
What’s new?
The TactiFlex Duo dual-energy contact force catheter enables seamless delivery of both radiofrequency and biphasic pulsed field energy, fully integrated with the three-dimensional mapping system, offering physicians enhanced procedural control and adaptability within a familiar point-by-point workflow.
The FOCALFLEX study evaluated the clinical feasibility and safety of this novel dual-energy system in patients with paroxysmal atrial fibrillation, including acute assessments of pulmonary vein isolation durability and real-time procedural metrics.
The system was found to be safe, with a 1.4% primary safety adverse event rate, and effective with 81.0% freedom from documented AF/AFL/AT recurrence after the 90-day blanking period at 6 months, supporting this integrated platform as a versatile tool for individualized ablation strategies.
Introduction
Pulmonary vein isolation (PVI) is the cornerstone in the interventional treatment of atrial fibrillation (AF), the most common sustained arrhythmia.1–3 Multiple trials have shown that radiofrequency (RF) ablation using contact force (CF) catheters for point-by-point PVI is safe and effective.4–6
Pulsed field ablation (PFA) is an emerging nonthermal ablation modality that achieves myocardial tissue selectivity by inducing irreversible electroporation through the application of high-voltage, microsecond-scale electric fields.7–9 PFA has shown efficacy comparable to thermal ablation for PVI, with low adverse event rates.10–12 Most existing data come from large-footprint, PFA-only catheters, which may pose limitations near sensitive structures like conduction tissue or ganglionated plexi and resultingly, procedural complications in large registries were often related to catheter manipulation rather than the energy source itself. The ability to switch between PFA and RF ablation delivered via a focal, small-footprint catheter can offer enhanced precision and safety, particularly when targeting thicker myocardium or areas close to the oesophagus or coronary vessels and when applying lesions sets beyond PVI.
The TactiFlex™ Duo Ablation Catheter, Sensor Enabled™ (Abbott, Plymouth, MN, USA, ‘TactiFlex Duo’) integrates CF sensing with dual-energy (PF + RF) capability, allowing tailored lesion formation with improved tissue selectivity and procedural flexibility. Preclinical data suggest durable lesions and favourable histological profiles with PFA, while maintaining the option for RF in anatomically challenging regions.13 The FOCALFLEX study evaluates the clinical performance of this approach in patients with paroxysmal AF. Here, we present 6-month follow-up results.
Methods
Study design
The FOCALFLEX study (NCT06271967) is a pre-market, prospective, single-arm, non-randomized, multicentre clinical investigation designed to investigate the safety and effectiveness of the TactiFlex Duo ablation catheter (Figure 1), the Volt™ PFA Generator, and EnSite™ X EP System with EnSite Pulsed Field Ablation Software (hereafter referred to as the TactiFlex PFA System) for the treatment of symptomatic, recurrent paroxysmal atrial fibrillation (PAF).
Figure 1.
TactiFlex™ duo PFA catheter design and key features. The novel TactiFlex Duo PFA ablation catheter combines dual pulsed field and radiofrequency (PF/RF) energy delivery with a flexible, laser-cut tip designed to support stable tissue contact. The handle incorporates intuitive controls with full EnSite™ X EP System integration, enabling real-time visualization and workflow compatibility. Nominal and low voltage therapy settings are available to support tailored ablation strategies within clinical workflows.
This study was sponsored by Abbott with oversight by a steering committee, publication committee, clinical events committee, and data safety monitoring board. Written informed consent was obtained from all patients. The study was conducted in accordance with the provisions of the Declaration of Helsinki and its amendments. At each centre, local ethics committees approved the study.
Patient population
Upon providing written informed consent, patients ≥18 years of age with symptomatic PAF were enrolled in the study. Consistent with the 2024 EHRA/HRS/APAC/LAHRS expert consensus statement on catheter and surgical ablation of atrial fibrillation, patients seeking first-line therapy were included and thus were not required to be drug refractory.2 Key exclusion criteria were left atrial diameter ≥ 5.0 cm, left ventricular ejection fraction < 35%, New York Heart Association (NYHA) class III or IV heart failure, body mass index > 40 kg/m2, previous left atrial catheter ablation procedure, and the presence of any implantable cardiac device. The full list of inclusion and exclusion criteria can be found in Supplementary material online, Table S1.
Ablation system
The investigational system is comprised of the 4 mm flexible-tip TactiFlex Duo ablation catheter, designed to transmit PFA therapy or RF current, the PFA generator, and a compatible electro-anatomical mapping system. The catheter has two magnetic sensors for visualization of the force direction arrow and deflection direction features on the EnSite X EP System. The monopolar, biphasic pulsed electric field is delivered with two voltage therapy options: nominal at 2400 V and low at 2100 V.
Procedure
The strategies of uninterrupted anti-coagulation for peri-operative management from the 2024 EHRA/HRS/APAC/LAHRS expert consensus statement on catheter and surgical ablation of atrial fibrillation for pre- and post-ablation were recommended to be followed.2 Left atrial appendage thrombus assessment was performed within 1 day prior to the ablation procedure. The form of anaesthesia, including general anaesthesia or conscious/deep sedation, used during the procedure was determined at the discretion of the physician. An activated clotting time (ACT) > 300 s was recommended for the duration of left atrium (LA) dwell time. Transseptal access was obtained according to physician preference using either fluoroscopy, intracardiac echocardiography, and/or trans-oesophageal echocardiography guidance. A pre-ablation voltage map and geometry of the LA was created using a multipolar mapping catheter (AdvisorTM HD Grid, AdvisorTM VL or FL; Abbott, Plymouth, MN, USA). PFA therapy was required to be used on the posterior LA, and RF therapy was required to be used in areas adjacent to the coronary arteries. Otherwise, use of PFA or RF was at the discretion of the physician. PFA could be delivered using either the nominal (2400 V) or low (2100 V) voltage therapy. For PFA, one application per ablation site was recommended, but more than one application could be applied up to a maximum for each therapy (nominal: four applications maximum per ablation site, low: two applications maximum per ablation site). Two voltage options were implemented based on preclinical evaluation to enable different amplitudes tailored to specific procedural workflows (e.g. general anaesthesia vs. deep sedation). The choice of voltage therapy was at the operator’s discretion. After completing initial PVI, a 20-min wait period was required before confirming electrical isolation of each PV via entrance block, at a minimum. Confirmation of exit block was also recommended. A required post-ablation voltage map was created using the same multipolar mapping catheter as the pre-ablation voltage map. Non-PV AF targets could be ablated, and bidirectional block was required to be confirmed across any ablation lines performed. Additional right atrial ablation could be performed if clinically indicated. RF ablation of a cavotricuspid isthmus (CTI) line using TactiFlex Duo was allowed if clinically indicated or per physician standard of care (e.g. prophylactic CTI line).
Post-procedural monitoring
Post-procedure follow-up included scheduled visits at 7 days, 35 days, 3 months, and 6 months. Follow-up will complete at the 12-month visit. A blanking period of 90 days post-index procedure was observed. Voltage remapping of the LA was required for any clinically indicated LA repeat ablation procedure. At 35 days, subjects were required to discontinue Class I and III AADs for AF/AFL/AT, unless the investigator determined in their medical judgment that the subject may benefit from a Class I or III AAD during the 9-month evaluation period (post-blanking period). Withdrawal of Class I and III AADs was to be attempted within 35 days after index procedure to assess for recurrence of symptoms and determine if a repeat ablation was needed during the blanking period. A 12-lead electrocardiogram (ECG) was performed at the 3- and 6-month visits and in case of symptoms. At least one trans-telephonic transmission (TTM) was required to be collected every 14 days between the 3- and 6-month visits. At the 6-month visit, a 24-h Holter monitor was administered.
Study endpoints
The primary safety endpoint was defined as the proportion of subjects experiencing a device and/or procedure-related serious adverse event (SAE) with onset within 7 days of any ablation procedure (index or repeat procedure within the blanking period) that uses the TactiFlex PFA System. A detailed list of the pre-defined primary safety events is included in Table 1.
Table 1.
Primary safety adverse events
| Primary Safety Population (n = 147) |
||||
|---|---|---|---|---|
| Endpoint criteria | Subjects % (n/n) |
No. of events | No. of procedure related events | No. of device related events |
| Atrio-oesophageal fistula | 0.0% (0/147) | 0 | 0 | 0 |
| Cardiac tamponade/perforation | 0.7% (1/147) | 1 | 1 | 1 |
| Death | 0.0% (0/147) | 0 | 0 | 0 |
| Heart block (atrioventricular block) | 0.0% (0/147) | 0 | 0 | 0 |
| Myocardial infarction | 0.0% (0/147) | 0 | 0 | 0 |
| Pericarditis | 0.0% (0/147) | 0 | 0 | 0 |
| Phrenic nerve injury resulting in diaphragmatic paralysis | 0.0% (0/147) | 0 | 0 | 0 |
| Pulmonary oedema | 0.0% (0/147) | 0 | 0 | 0 |
| Pulmonary vein stenosis | 0.0% (0/147) | 0 | 0 | 0 |
| Stroke/cerebrovascular accident | 0.0% (0/147) | 0 | 0 | 0 |
| Thromboembolism | 0.0% (0/147) | 0 | 0 | 0 |
| Transient ischaemic attack | 0.7% (1/147) | 1 | 1 | 1 |
| Vagal nerve injury/gastroparesis | 0.0% (0/147) | 0 | 0 | 0 |
| Major vascular access complication/Major bleeding | 0.0% (0/147) | 0 | 0 | 0 |
| Device and/or procedure related cardiovascular and/or pulmonary adverse event that prolongs hospitalization for more than 48 h | 0.0% (0/147) | 0 | 0 | 0 |
| Total | 1.4% (2/147) | 2 | 2 | 2 |
The acute procedural effectiveness endpoint was defined as confirmation of entrance block in all PVs after a minimum waiting period of 20 min. Acute procedural failure was defined as the inability to isolate all targeted PVs using only the TactiFlex PFA catheter for ablation. First-pass isolation was defined as confirmation of entrance block in all treated pulmonary veins following the initial minimum 20-min waiting period without the need for additional ablation during the waiting period.
The primary effectiveness endpoint was the rate of freedom from documented (symptomatic or asymptomatic) AF/AFL/AT episodes of >30 s duration that are documented by protocol-specified 12-lead ECG, TTM or Holter Monitor after the index ablation procedure through 6 months of follow-up (after a 90-day blanking period following the index ablation procedure). The full list of reasons for primary effectiveness failure, along with their rates, is included in Supplemental material online, Table S2. Clinical success was defined as freedom from symptomatic primary effectiveness endpoint failure. The AAD-free effectiveness rate was defined as freedom from primary effectiveness endpoint failure without any use of Class I or III antiarrhythmic drugs after the 90-day blanking period.
Retrospective PFA Index analysis
The PFA Index (PI) is an additional metric for operators to use as a guide during cardiac ablation procedures. The PI metric is a real-time integration of factors associated with lesion formation to measure the therapy effect of PFA energy delivery. These factors include the number of bursts delivered, the percentage of time that the CF is at least 5 g, and the change in the local tissue response.14 As the PI metric was not available in the study, values were retrospectively calculated for a subset of 69 cases from Index Procedures of patients who consented to R&D use. All signals needed for the PI calculations were exported from each clinical case, and all AutoMarks were screened to ensure high-fidelity force and intracardiac impedance recordings during PF ablations. PV encirclement paths were reconstructed from AutoMark coordinates to compute the AutoMark distance (AMD), and anatomical assignments were determined by expert clinical specialists. Intuitively, clinical procedures that consistently achieve effective, well-placed lesions are more likely to have successful outcomes. This retrospective analysis quantified whether higher adherence to PI-AMD targets is positively associated with freedom from arrhythmia recurrence at 6 months post-ablation. Targets were selected based on the maximum positive predictive value achieved at one application.
Statistical methods
Continuous variables are reported as mean ± SD, median, and interquartile range (IQR), irrespective of the normality of their distribution. Categorical variables are expressed as number (percent). Changes in patient-reported outcomes were evaluated using the paired t-test. Primary effectiveness at 6 months was estimated using Kaplan–Meier analysis with Greenwood standard error. Analyses were performed using SAS version 9.4 (SAS Institute, Inc.).
Results
Baseline characteristics
A total of 150 subjects with PAF were enrolled in the FOCALFLEX study at 21 sites worldwide from August 2024 to January 2025 (see Supplementary material online, Table S3). A total of three subjects were withdrawn prior to insertion of the ablation catheter, for a total of 147 subjects in the catheter-inserted population. An additional three subjects were withdrawn after insertion of the catheter but prior to ablation, for a total of 144 subjects in the PF/RF delivered population (PFAD). There was one subject who did not have the right PVs treated with the TactiFlex PFA System for a total of 143 subjects in the per-protocol population (PP). Subject disposition is detailed in the CONSORT diagram (Figure 2). The catheter-inserted population was 62.6% (92/147) male with an average age of 62.0 ± 10.0 years, CHA2DS2-VASc score of 1.7 ± 1.4 (Table 2), and hypertension was the most frequent comorbidity (45.6%, 67/147) (see Supplementary material online, Table S4). Previous use of Class I/III AADs was reported in 46.9% of subjects; previous use of Class II/IV/V AADs was reported in 73.5% of subjects (see Supplementary material online, Table S5).
Figure 2.
Disposition of subjects.
Table 2.
Demographics and baseline characteristics
| Catheter inserted (n = 147) |
|
|---|---|
| Age (years) | |
| Mean ± SD (n) | 62.0 ± 10.0 (147) |
| Median (Q1, Q3) | 64.0 (55.0, 69.0) |
| Range (min, max) | (33.0, 79.0) |
| Height (cm) | |
| Mean ± SD (n) | 176.0 ± 9.1 (147) |
| Median (Q1, Q3) | 176.0 (168.0, 183.0) |
| Range (min, max) | (155.0, 202.0) |
| Weight (kg) | |
| Mean ± SD (n) | 86.1 ± 15.5 (147) |
| Median (Q1, Q3) | 85.0 (75.0, 95.6) |
| Range (min, max) | (51.0, 128.0) |
| BMI (kg/m2) | |
| Mean ± SD (n) | 27.8 ± 4.4 (147) |
| Median (Q1, Q3) | 27.0 (25.0, 30.5) |
| Range (min, max) | (17.9, 38.7) |
| Sex | |
| Female | 37.4% (55/147) |
| Male | 62.6% (92/147) |
| NYHA Classification I |
20.5% (30/146) |
| II | 4.1% (6/146) |
| III | 0.0% (0/146) |
| IV | 0.0% (0/146) |
| No heart failure | 75.3% (110/146) |
| CHA2DS2Vasc Score | |
| Mean ± SD (n) | 1.7 ± 1.4 (147) |
| Median (Q1, Q3) | 2.0 (0.0, 3.0) |
| Range (min, max) | (0.0, 6.0) |
| LVEF (%) | |
| Mean ± SD (n) | 60.5 ± 6.3 (147) |
| Median (Q1, Q3) | 60.0 (56.0, 65.0) |
| Range (min, max) | (44.0, 78.0) |
| LA diameter (mm) | |
| Mean ± SD (n) | 38.4 ± 5.5 (147) |
| Median (Q1, Q3) | 39.0 (34.0, 42.0) |
| Range (min, max) | (25.0, 50.0) |
| Arrhythmia history | 100.0% (147/147) |
| Paroxysmal AF | 100.0% (147/147) |
| Persistent AF | 0.0% (0/147) |
| Atrial flutter | 11.6% (17/147) |
| Atrial tachycardia | 3.4% (5/147) |
| Ventricular tachycardia | 1.4% (2/147) |
| Bradycardia | 9.5% (14/147) |
| Supraventricular tachycardia | 1.4% (2/147) |
AF, atrial fibrillation; NYHA, New York Heart Association; LA, left atrium; LVEF, left ventricular ejection fraction
Procedural characteristics
The average procedure time was 112.2 ± 29.5 min, including the protocol-mandated 20-min waiting period and pre- and post-procedure voltage mapping, with an average LA dwell time and PV ablation time of 81.1 ± 19.7 and 47.4 ± 16.4 min, respectively (Table 3). The average fluoroscopy time was 7.5 ± 5.7 min, with one case performed without the use of fluoroscopy. The average number of PFA applications was 95.5 ± 37.1, with an average of 93.3 ± 33.0 applications targeting the PVs. PF alone was used in 79.2% of subjects while a combination of RF and PF was used in 20.1% of subjects. RF alone was used in one subject (0.7%) because the clinical study generator was unable to deliver PF energy due to an issue with the clinical study version of the R-wave detection algorithm. Ablation targets beyond the PVs were ablated in 20.8% of cases, with CTI line (18/144), posterior wall isolation (12/144), roof line (9/144), and mitral isthmus line (1/144) the most common (Table 4). Operators most commonly used nominal therapy exclusively (89%), while 10% employed a combination of nominal and low therapy, and 1% used low therapy alone. General anaesthesia was the most common sedation type, used in 65.3% of cases (94/144).
Table 3.
Procedural characteristics
| PF/RF delivered (n = 144) |
|
|---|---|
| Total procedure time (min) | |
| Mean ± SD (n) | 112.2 ± 29.5 (144) |
| Median (Q1, Q3) | 109.5 (90.0, 127.5) |
| Range (Min, Max) | (74.0, 261.0) |
| Fluoroscopy time (min) | |
| Mean ± SD (n) | 7.5 ± 5.7 (144) |
| Median (Q1, Q3) | 6.0 (4.0, 9.6) |
| Range (Min, Max) | (0.0, 44.0) |
| LA dwell time (min) | |
| Mean ± SD (n) | 81.1 ± 19.7 (144) |
| Median (Q1, Q3) | 79.0 (68.0, 94.0) |
| Range (Min, Max) | (34.0, 145.0) |
| Total PV ablation time (min) | |
| Mean ± SD (n) | 47.4 ± 16.4 (144) |
| Median (Q1, Q3) | 43.5 (36.0, 55.0) |
| Range (Min, Max) | (18.0, 112.0) |
| PV ablation RF time (s) | |
| Mean ± SD (n) | 386.4 ± 419.1 (12) |
| Median (Q1, Q3) | 253.0 (115.5, 465.5) |
| Range (Min, Max) | (15.0, 1463.0) |
| Total PFA applications for PVs | |
| Mean ± SD (n) | 93.3 ± 33.0 (144) |
| Median (Q1, Q3) | 88.5 (75.0, 105.5) |
| Range (Min, Max) | (0.0, 206.0) |
| Multipolar mapping catheter used to map the left atrium | |
| HD grid | 78.5% (113/144) |
| Advisor VL | 6.9% (10/144) |
| Advisor FL | 14.6% (21/144) |
| Anaesthesia | |
| General anaesthesia | 65.3% (94/144) |
| Low tidal volume/high respiratory rate implemented | 36.2% (34/94) |
| Conscious sedation | 0.7% (1/144) |
| Deep sedation | 34.0% (49/144) |
PF, pulsed field; PFA, pulsed field ablation; RF, radiofrequency.
Table 4.
Energy delivery type by location
| Energy type delivered | PF only | PF + RFa | RF only | Number treated (n = 144) |
|---|---|---|---|---|
| LSPVb | 94.4% (136/144) | 4.9% (7/144) | 0.7% (1/144) | 100.0% (144/144) |
| LIPV | 93.9% (123/131) | 4.6% (6/131) | 1.5% (2/131) | 100.0% (131/131) |
| RSPV | 94.4% (135/143) | 4.2% (6/143) | 1.4% (2/143) | 99.3% (143/144) |
| RIPV | 94.4% (135/143) | 4.2% (6/143) | 1.4% (2/143) | 99.3% (143/144) |
| Right middle PV | 100.0% (6/6) | 0.0% (0/6) | 0.0% (0/6) | 100.0% (6/6) |
| Roof line | 5.6% (8/144) | 0.0% (0/144) | 0.7% (1/144) | 6.3% (9/144) |
| Posterior wall isolation | 8.3% (12/144) | 0.0% (0/144) | 0.0% (0/144) | 8.3% (12/144) |
| Posterior line | 4.2% (6/144) | 0.0% (0/144) | 0.0% (0/144) | 4.2% (6/144) |
| Mitral isthmus line | 0.7% (1/144) | 0.0% (0/144) | 0.0% (0/144) | 0.7% (1/144) |
| High crista terminalis | 0.7% (1/144) | 0.0% (0/144) | 0.0% (0/144) | 0.7% (1/144) |
| Cavotricuspid isthmus line | 0.0% (0/144) | 0.0% (0/144) | 12.5% (18/144) | 12.5% (18/144) |
| Inferior line | 0.0% (0/144) | 0.0% (0/144) | 0.7% (1/144) | 0.7% (1/144) |
| SVT | 0.0% (0/144) | 0.0% (0/144) | 0.7% (1/144) | 0.7% (1/144) |
LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; PV, pulmonary vein; SVT, supraventricular tachycardia; PF, pulsed field; PFA, pulsed field ablation; RF, radiofrequency.
aPF + RF does not indicate stacked lesions.
b13 Left common PVs are included in LSPV.
Safety endpoints
A primary safety endpoint event occurred in 1.4% (2/147) subjects, with one event of cardiac tamponade/perforation and one event of transient ischaemic attack (TIA) (Table 1). The subject who experienced cardiac tamponade had been treated with PFA only, and immediate post-procedural transthoracic echocardiography confirmed the absence of pericardial effusion. Approximately 1 h later, the subject became symptomatic and underwent pericardiocentesis, after which the subject stabilized and was discharged the following day. Intracardiac echocardiography (ICE) was not used during the procedure, and after pericardial drainage the bleeding source could no longer be directly visualized, precluding definitive identification of the perforation site. Based on the treating physician’s assessment, the tamponade was attributed to the transseptal puncture.
The subject who experienced TIA had a NIH Stroke Scale score of 1 at baseline due to left leg drift. During the procedure, the measure ACTs were consistently above 300. Post-index procedure and prior to discharge, the subject developed acute onset of lower left limb weakness and headache. Head CT/angiography and brain MRI/MRA showed no intracranial pathology. Echocardiography demonstrated normal biventricular function, normal atria, and no significant valvular pathologies. Based on the clinical presentation and imaging, the subject's symptoms were diagnosed as TIA. Continued anticoagulant medication was prescribed. Symptoms fully resolved overnight, and the subject was ambulatory the next morning and discharged.
One subject experienced a myocardial infarction on post-procedure day 9. In accordance with study protocol, this event was not classified as a primary safety adverse event but was adjudicated as an SAE. Coronary angiography demonstrated calcification, and the subject was managed with continuation of medical therapy. The subject’s medical history included a prior myocardial infarction and percutaneous coronary intervention, consistent with underlying coronary vascular disease. Overall, these findings indicate structural coronary disease as the most likely mechanism of the myocardial infarction. Throughout the 6-month follow-up period, no deaths, oesophageal lesions, pulmonary vein stenosis, or phrenic nerve injury were observed.
Effectiveness endpoints
Acute effectiveness
Acute procedural effectiveness was achieved in 100.0% (143/143) of PP subjects where all veins were treated with the TactiFlex PFA System. One subject did not receive treatment of the right pulmonary veins with the TactiFlex PFA System due to a clinical study generator issue, and the procedure was finished with a market-released system; therefore, acute procedural effectiveness was achieved in 99.3% of PFAD subjects (143/144) and 99.6% of pulmonary veins (566/568). First-pass isolation was achieved in 86.1% of PFAD subjects (124/144) and 94.0% of pulmonary veins (534/568).
Chronic effectiveness
Freedom from documented AF/AFL/AT recurrence at 6 months was 81.0% (Figure 3). Freedom from the primary effectiveness endpoint at 6 months was 79.6%. The most common effectiveness endpoint failure event was documented recurrence of AF/AFL/AT, occurring in 18.8% (27/144) of subjects (see Supplementary material online, Table S2). Clinical success was achieved in 83.8% of PFAD subjects. The AAD-free effectiveness rate was 74.0%. A total of 30 subjects remained on a Class I or III AAD after the blanking period based on investigator judgment that continued therapy was clinically warranted; 25 of these subjects had no new or increased dose of a Class I or III AAD. Arrhythmia monitoring compliance was high with 94.4% (136/144) of subjects completing either a Holter, TTM, or ECG for confident capture of documented AF/AFL/AT recurrence as one of the primary effectiveness endpoint events at 6 months. Of the expected 1000 TTM transmissions from the 3-month visit through the end of the 6-month visit window, 889 were received resulting in an overall TTM compliance rate of 88.9%. After the 90-day blanking period, one subject required a repeat ablation to treat atypical atrial flutter for a low repeat ablation rate at 6 months of 0.7% (1/144).
Figure 3.
Effectiveness at 6 months in the FOCALFLEX study. Displayed are the 6-month Kaplan–Meier estimates of (A) freedom from any primary effectiveness endpoint failure, (B) freedom from documented atrial (AF/AT/AFL) recurrence, (C) clinical success, and (D) AAD-free effectiveness.
Patient-reported outcomes
Patient-reported quality-of-life scores on the visual analogue scale component of the EQ-5D-5L questionnaire had a 6-month paired change of 6.2 ± 14.1 from baseline (mean increase of 6.6); the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire had a 6-month paired change of 22.1 ± 22.2 from baseline (mean increase of 22.0) (see Supplementary material online, Tables S6 and S7).
Retrospective PFA Index analysis
The median PI value for lesions created with one application of the nominal voltage therapy was 39 (IQR 32, 48) and 47 (IQR 38, 55) for one application of the low voltage therapy. When analysed in relation to single-procedure success at 6 months, cases that had 80% of anterior lesions with a PI value ≥25 and posterior lesions with a PI value ≥20 and had 90% of lesions with an AMD ≤6 mm had a positive predictive value of 85% for single-procedure success at 6 months.
Discussion
The FOCALFLEX study is the first in-human study to assess the safety and effectiveness of the dual-energy TactiFlex PFA System for the treatment of PAF. The results support the safety and effectiveness of this system, with a 1.4% primary safety event rate, per-subject acute effectiveness of 99.3%, and 6-month freedom from documented AF/AFL/AT recurrence at 6 months of 81.0%.
A combined RF/PF catheter provides procedural versatility, enabling operators to tailor energy delivery to the anatomy and substrate rather than committing to a single ablation modality. However, unlike large-footprint ‘one-shot’ PFA technologies, point-by-point strategies may be associated with different procedural characteristics. Compared to ‘one-shot’ PFA technologies, RF/PF platforms are characterized by slightly longer procedure durations but lower fluoroscopy time.11,15
This study adds to the growing body of literature demonstrating safety and effectiveness for focal dual-energy AF ablation. In previous reports of results using focal technologies, the SPHERE Per-AF trial using a lattice-tip catheter for AF ablation in patients with persistent AF showed non-inferiority to conventional RF ablation for safety and efficacy.16 The SmartfIRE study, a prospective, single-arm, multicentre evaluation in patients with paroxysmal AF, demonstrated safety and success, as well as durability in a subset of remapped patients.15,17
The primary safety endpoint rate observed in this study (1.4%) aligns with previous studies reporting early experience with novel technologies.5,6,15,18,19 The rates of cardiac tamponade (0.7%) and TIA (0.7%) were comparable to previous studies.10,11,15,20,21 A single subject with established coronary artery disease experienced a myocardial infarction post-procedure day 9, which was adjudicated as an SAE and managed medically; this event was attributed to underlying coronary disease. Although coronary spasm cannot be completely excluded, it was considered unlikely given the subject’s clinical history. Importantly, no other delayed myocardial ischaemia or malignant arrhythmia were observed during the 6-month follow-up period.22
The FOCALFLEX study showed a 99.6% acute success rate and 94.0% first-pass isolation rate per PV. These metrics compare favourably with published data for other focal catheters, where first-pass isolation rates range between 80% and 90%.5,15 For comparison, the ECLIPSE AF trial reported 92.2% first-pass isolation using optimized PFA with CF-sensing catheters, while dual-energy catheter studies achieved 95% and 96.8%, respectively.15,18,23 The use of dual-energy catheters within their proprietary system offers seamless integration with advanced electroanatomical mapping systems, enabling precise lesion delivery, CF monitoring, and tailored energy application using both RF and PFA. The TactiFlex PFA System was extensively characterized and verified in a comprehensive preclinical program. The system’s therapy was validated specifically for the TactiFlex Duo catheter design, including its electrode configuration, spacing, and surface geometry, to promote consistent lesion formation across a wide range of tissue types and anatomical conditions. Bench and in vivo studies demonstrated reproducible lesion depth, homogeneous circumferential coverage, and selective myocardial ablation with preservation of adjacent non-cardiac structures such as the oesophagus and phrenic nerve.8,16,24 These findings confirm that the system provides controlled energy distribution, predictable tissue selectivity, and robust safety margins, supporting reliable clinical translation and consistent lesion durability. Post-ablation LA maps within the FOCALFLEX study revealed precise ablation lesions, supported by the high first-pass isolation rate (Figure 4).
Figure 4.
Pre- and post-ablation electroanatomic maps. TactiFlex Duo is integrated with the EnSite X EP System, with maps depicting the associated AutoMarks after therapy delivery. Blue AutoMarks indicate >10 g of contact was achieved during PFA lesion delivery; white AutoMarks indicate >5 g and <10 g of contact. Figure 4A illustrates a pulmonary vein isolation-only ablation; Figure 4B illustrates PVI with an added cavotricuspid isthmus line created with RF (red AutoMarks).
At 6 months, freedom from AF/AFL/AT recurrence after the blanking period was 81.0%, with a primary effectiveness endpoint of 79.6%, aligning with or exceeding outcomes typically reported for thermal ablation systems in similar populations.5,15,25 Stringent rhythm monitoring within clinical trials may increase the detection of short, asymptomatic atrial arrhythmias that would otherwise remain clinically unnoticed in routine practice. This heightened surveillance can artificially inflate recurrence rates and underestimate the apparent effectiveness of ablation. Clinical success, allowing for asymptomatic recurrences, reached 83.8%, and nearly three-quarters (74.7%) of subjects who discontinued AADs remained arrhythmia-free. There was only one repeat ablation procedure (0.7%) between the 90-day blanking period and the 6-month follow-up. Together, these findings confirm durable lesion formation and favourable rhythm outcomes, supporting the procedural efficiency and therapeutic efficacy of the TactiFlex PFA System for ablation in patients with atrial fibrillation.
The procedural performance of the TactiFlex PFA System in this cohort demonstrates a favourable balance between efficiency and efficacy when compared with prior-generation PFA and conventional RF systems. The mean total procedure time of 112.2 ± 29.5 min, which included protocol-mandated voltage mapping and a 20-min waiting period, reflects a streamlined workflow inclusive of comprehensive procedural assessments. The mean left atrial dwell time (81.1 ± 19.7 min) and transpired PV ablation time (47.4 ± 16.4 min, calculated from first to last PV application) indicate efficient lesion delivery with minimal fluoroscopy exposure (7.5 ± 5.7 min). The average number of PFA applications in the PVs (93.3 ± 33.0), coupled with the high first-pass and acute success rates, suggests that successful PVI can be achieved with a moderate number of applications.
Within the FOCALFLEX study, feasibility of the dual-energy ablation system was shown for various anaesthesia protocols. The ability to use dual-energy catheters under both general anaesthesia and deep sedation provides important procedural flexibility and broadens clinical applicability across different patient populations and institutional practices. Some centres prefer deep sedation for efficiency and resource management, while others rely on general anaesthesia for improved patient stability and catheter control, particularly during long or complex procedures. A dual-energy catheter system that performs reliably under both conditions ensures consistent lesion quality and safety, regardless of sedation strategy. This versatility allows clinicians to tailor the approach to individual patient needs, comorbidities, and procedural complexity, without compromising ablation effectiveness.
The FOCALFLEX study demonstrated a significant (P < 0.0001) improvement in patient-reported quality of life. A 6-month paired analysis showed a + 6.2 ± 14.1 change in the EQ-5D-5L Visual Analog Score and a + 22.1 ± 22.2 change in the AFEQT overall score from baseline. PFA is recognized for its safety and tissue selectivity, but it is essential to prove that these benefits also lead to improved patient experience.
The retrospective analysis of cases to determine threshold values of a novel index, PI, provides initial insight into values that are positively associated with single-procedure success at 6 months. This index was not available for prospective use during the FOCALFLEX trial, but retrospective analysis of trial cases can be used to guide prospective clinical use. The impact of PI in a prospective clinical setting remains to be determined.
A dual-energy focal catheter offers clinical relevance in real-world settings where combining the benefits of both energy modalities is advantageous. This ablation system enables seamless switching between PF and RF energy within a familiar workflow, allowing for greater procedural flexibility. Its focal design supports targeted treatment across diverse anatomies, including areas beyond PVI, such as CTI ablation or linear ablation within the LA.
Limitations
This study is limited by its single-arm design, without separate RF-only and PF-only comparator groups. While acute and 6-month PVI durability data are promising, 12-month outcomes are needed to confirm long-term safety and efficacy. Mandatory remapping during follow-up was not performed, warranting broader evaluation to assess PV reconnection rates. The PFA index was not available during the procedures and was therefore calculated retrospectively in a subset of cases, which limits conclusions regarding its direct procedural or clinical impact. The absence of continuous rhythm monitoring represents an additional limitation, as asymptomatic arrhythmia recurrences may have remained undetected. Due to the limited number of recurrence events during the current follow-up period, analysis of predictors of arrhythmia recurrence was not feasible and will be addressed in a 12-month analysis.
Conclusion
The 6-month results from the FOCALFLEX CE Mark study showcase the high degree of safety, acute- and long-term effectiveness, workflow utility, and quality-of-life improvement achieved with use of the TactiFlex PFA System for the treatment of paroxysmal AF. Further analysis of ongoing long-term follow-up results is warranted.
Supplementary Material
Acknowledgements
The authors would like to acknowledge and thank Carlie Garg and Alyna Crist for their assistance in manuscript preparation, Jaylynn Markey for image preparation, and Beth Harlos and John Tranter for assistance with data analysis. We also thank the FOCALFLEX CE Mark trial investigators, sites, their dedicated staff, patients, and the Field Clinical Specialist team.
Contributor Information
Martin Manninger, Department of Medicine, Division of Cardiology, Medical University of Graz, Auenbruggerplatz 15, Graz A-8036, Austria.
Daniel Scherr, Department of Medicine, Division of Cardiology, Medical University of Graz, Auenbruggerplatz 15, Graz A-8036, Austria.
Alan Bulava, Ceske Budejovice Hospital and Faculty of Health and Social Sciences, University of South Bohemia, Ceske Budějovice, Czechia.
Jonathan Kalman, Melbourne Heart Center, The Royal Melbourne Hospital, Parkville, Melbourne, VIC 3050, Australia; University of Melbourne, Parkville, Melbourne, VIC 3050, Australia.
Prashanthan Sanders, Centre for Heart Rhythm Disorders, Adelaide University and the Royal Adelaide Hospital, Adelaide, SA, Australia.
Paolo Della Bella, Cardiac Arrhythmology and Electrophysiology Unit, Ospedale San Raffaele, Milan, Italy.
Martin Reinhold Martinek, Innere Medizin II - Kardiologie, Angiologie und Interne Intensivmedizin, Ordensklinikum Linz Elisabethinen, Linz, Austria.
Isabel Deisenhofer, Department of Electrophysiology, TUM University Hospital, German Heart Center, Munich, Germany.
Adrianus P Wijnmaalen, Department of Cardiology, Willem Einthoven Center of Arrhythmia Research and Management, Leiden University Medical Center, Leiden, Netherlands.
Joaquin Osca, Servicio de Cardiología, Hospital Universitari I Politecnic La Fe, Valencia, Spain.
Ignacio García Bolao, Cardiology and Cardiac Surgery, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain.
Javier Moreno, Arrhythmia Unit, Hospital Universitario Ramón y Cajal, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain.
Pierre Jaïs, IHU Liryc, Bordeaux, France; American Hospital of Paris, Paris, France.
Mads Brix Kronborg, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
Estelle Gandjbakhch, Sorbonne Université, APHP, Hôpital Pitié Salpetriere, Institut de Cardiologie, ICAN, Paris, France.
Helmut Pürerfellner, Innere Medizin II - Kardiologie, Angiologie und Interne Intensivmedizin, Ordensklinikum Linz Elisabethinen, Linz, Austria.
Sara Muldoon, Abbott Medical, Plymouth, MN, USA.
Nick Dirckx, Abbott Medical, Plymouth, MN, USA.
Virginia Woods, Abbott Medical, Plymouth, MN, USA.
John Silberbauer, Sussex Cardiac Centre, Brighton, UK.
Supplementary material
Supplementary material is available at Europace online.
Funding
This work was supported by Abbott. S.P. is supported by an Investigator Grant from the National Health and Medical Research Council of Australia.
Data availability
The data underlying this article are available in the article and in its online Supplementary material.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The data underlying this article are available in the article and in its online Supplementary material.