This was a single center retrospective study that included patients with AF, over 18 years of age, and electively referred for symptomatic AF ablation, between June 2022 and July 2023.

Patients were excluded from the procedure if they had AF secondary to electrolyte imbalance, thyroid disease, or reversible or non-cardiac cause; left atrial thrombus or a contraindication for anticoagulation.

Clinical parameters – demographics, major cardiovascular risk factors, symptomatic status – were collected.

Prior to the procedure, all patients underwent cardiac computed angiography for atrial and pulmonary vein assessment, and to rule-out left atrial appendage thrombus.18 Treatment with uninterrupted systemic anticoagulation therapy was required for at least three weeks prior to study treatment. During the ablation procedure, unfractionated heparin was administered right before transseptal puncture to achieve and maintain an activated clotting time of between 300 and 350 seconds.19 Ultrasound guidance was used to obtain femoral venous access.

Ablation was performed under fluoroscopy guidance with or without the use of a three-dimensional electroanatomic mapping system (CARTO 3, BiosenseWebster, Diamond Bar, CA, USA). All ablation procedures included were managed with anesthesiology on site. They were performed either under conscious deep sedation using continuous remifentanil and propofol infusion or general anesthesia, at the physician's discretion. In this approach, coughing, patient movement or patient discomfort were not an issue.

During the PFA procedure, a 6F quadripolar catheter was used to pace the right ventricle as needed during periods of asystole.

The novel multielectrode pentaspline PFA catheter (FARAPULSE Boston Scientific) was used. Catheters were placed in the coronary sinus and his bundle region/right ventricle. As outlined in the MANIFEST-PF trial,17 PFA protocol comprises a pentaspline PFA catheter (Farawave, 12-Fr) inserted through a 13-Fr steerable sheath with a transparent shaft (Faradrive) into the left atrium (LA). Once the recommended straight-tip 0.035 guidewire (Amplatz extra stiff straight wire; Cook Inc.) is positioned in each target PV, the PFA catheter is placed at the ostium of each PV to apply a total of eight PF lesions per vein. Additional lesions were performed on larger veins or pulmonary trunk whenever abnormal signals were found. The lesions are distributed in ‘basket’ and ‘flower’ configurations, with rotation between each pair of lesions. For ablation of the posterior LA wall, the catheter is deployed in the flower configuration and placed along the posterior LA to deliver overlapping sets of pulses at each location. The pulse field voltage amplitude can vary between 1.8 and 2.0 kV, with 2.0 kV typically being used. The total procedure time was the duration from obtaining vascular access to the removal of catheters from the patient.

According to the hospital's policy, patients are scheduled for a follow-up appointment usually at three months after AF ablation. Oral anticoagulation therapy was performed at least until this reassessment and adjusted according to the CHA2DS2-VASc score.5 The administration of antiarrhythmic drugs after ablation was at the treating physician's discretion.

The primary effectiveness outcome was acute success, defined as first pass isolation (PW and PV isolation).

The secondary effectiveness outcome was relapse of any atrial arrhythmia after a three-month blanking period, and was defined as the presence of AF, atrial flutter, or any atrial arrhythmia on routine electrocardiogram (ECG) or 24-hours Holter test, extracted from electronic medical records.

The main safety endpoint was a composite of procedure-related death, atrioesophageal fistula, cardiac tamponade, myocardial infarction, cerebrovascular events, persistent phrenic nerve injuries, PV stenosis or vascular access complications.

Categorical values are presented as absolute numbers (and percentage). Continuous variables as mean±standard deviation (normal distribution) or as median and interquartile range (IQR; non-parametric). Kolmogorov–Smirnov test was used to test normality of the variables.

Independent sample T-test and Mann–Whitney tests were applied for comparison where appropriate. Statistical significance was set at p-value <0.05 (two-sided). All analyses were performed using Statistical Package for the Social Sciences Statistics v27.0 (IBM Corporation, Armonk, NY, USA).

Overall, we studied 123 consecutive patients who were electively referred for symptomatic AF ablation, aged 62±11 years, 72 (59%) male, mean CHA2DS2-VASc score of 2±1 points. Fifty-two percent of patients presented paroxysmal AF, and 21 patients (17%) had undergone a previous ablation procedure. No statistical differences were found in comparative analyses among paroxysmal and non-paroxysmal AF redo patients (Supplemental Table 1). At transthoracic echocardiogram evaluation, a median left ventricular ejection fraction of 61% [IQR 60–65%] was found.

Regarding cardiovascular risk factors and comorbidities: 65% (n=80) had a previous diagnosis of hypertension; 22% (n=27) patients had diabetes and 8% (n=10) presented congestive HF. Demographic and clinical data are summarized in Table 1. All patients were under uninterrupted systemic anticoagulation therapy for at least three weeks prior to study treatment.

As previously stated, all patients performed a CT scan before ablation procedure for PV mapping, and to rule-out LA appendage thrombus, with a median CT scan derived left atrial volume index of 55 mL/m2 (IQR 41–67 mL/m2). All procedures were performed with only one transeptal puncture.

Electroanatomical mapping was performed in 88 patients (n=72%) – all with CARTO®3D – in relation to the initial experience of the operators and, mainly, when posterior wall isolation (PWI) was planned. All patients underwent PVI using the pentaspline PFA catheter. Of the 123 participants who underwent ablation, PVI was performed in all of them. PWI was performed in 43 patients (35%), based on the operator's description, on LA volume and primarily guided by the assessment of fragmented potentials and/or left atrial fibrosis. The median procedure time was 83 min [IQR 59–117 min]. Of this total procedure time, fluoroscopy time was 11.6 min [IQR 8.2–15.6 min] – Table 2. Comparing these times in the first half of the procedures performed with those in the following months, it was found that the procedure [89 (IQR 68–119) vs. 77 (IQR 46–113) min, p=0.023] and fluoroscopy [13 (IQR 10–16) vs. 10 (IQR 8–13) min, p=0.005] times were significantly longer in the initially performed procedures. In a comparative analysis based on different workflow approaches (Supplemental Table 2): fluoroscopy-guided PVI; three dimensional (3D) mapping-guided PVI; fluoroscopy-guided PVI+PWI (if used); and 3D mapping-guided PVI+PWI, we found a significant statistical difference related to the procedure (p<0.001) and fluoroscopy (p=0.022) times. Patients who underwent fluoroscopy-guided PVI presented the lowest median procedure time and the lowest median fluoroscopy time.

Among patients who underwent redo-AF ablation, only reconnected PVs were isolated, with a mean of 2±1 reconnected veins per patient.

The primary effectiveness endpoint (defined as first pass isolation – PW and PVI) was achieved in 100% of patients. Over 290 (IQR 169–387) days of follow-up, 112 patients (91%) were in sinus rhythm, whereas 9% of patients had AF recurrence (two with paroxysmal AF and nine with persistent AF). Basal and procedural characteristics were similar between the relapse and the non-relapse group (Table 3). In addition to age, no differences were found between patients with paroxysmal and non-paroxysmal AF with recurrence of AF during follow-up (Supplemental Table 3).

There were no esophageal complications, persistent phrenic nerve injuries, cerebrovascular events, myocardial infarction, PV stenosis or procedure-related deaths (Figure 1). There was no evidence of ST-segment elevation, neither coronary spasm, arrhythmias, or ventricular wall motion abnormalities.

Figure 1.

Pulse field ablation procedure – peri/post-procedural complications.

(0.09MB).

Overall, the number of PFA applications was less than 80, with no cases of hemolysis being reported.

Two patients (1.6%) experienced acute cardiac tamponade. While the causes were not easy to identify, both these procedures were done early in the center experience, and in both cases, the Farawave™ catheter was removed from Faradrive™ sheath and the LA was remapped with a Pentaray® catheter after ablation. As such, they were attributed to catheter manipulation. Both complications were managed with pericardiocentesis, without the need for cardiac surgery. The other complications were vascular, in 4% of cases: three femoral hematomas, one femoral pseudoaneurysms and one arteriovenous fistula – all treated with conservative measures. Also, the hematoma complications were minor as they did not prolong hospitalization.