Background Pulsed field ablation (PFA) may overcome key limitations of radiofrequency ablation (RFA) when treating premature ventricular contractions (PVCs) in anatomically complex regions (eg, left ventricular summit or intramural outflow tract [OT]). However, the safety and efficacy of PFA in OT PVCs remain to be determined. Objectives This study sought to assess the feasibility, safety, and midterm clinical outcomes of focal PFA for outflow tract PVCs. Methods In this prospective multicenter study, 80 patients with symptomatic OT PVCs underwent focal monopolar PFA using the CENTAURI generator at 4 European centers. Acute procedural outcome, complications, and mid-term efficacy were assessed. Follow-up at 3 and 6 months included 24-hour Holter electrocardiogram and clinical evaluation. Success was defined as >80% reduction in daily PVC burden off antiarrhythmic drugs. Results PVCs originated from the right ventricular OT (RVOT) in 61% of cases, with the remainder from the left ventricular OT (LVOT) and left ventricular summit. Acute procedural success was achieved in all. At a median follow-up of 8 months, clinical success was achieved in 88%, and PVC burden was significantly reduced from 21.4% (Q1-Q3: 11.9%-30.0%) before the procedure to 0.0% (Q1-Q3: 0.0%-2%) (P < 0.001) at follow-up. Success rates of ablation at the RVOT, endocardial LVOT, and left ventricular summit were 94%, 89%, and 72%, respectively. Among patients with prior failed RFA, 14 (93%) of 15 experienced no recurrence. One major (ischemic stroke; 1%) and 7 minor (9%) complications occurred. Nitroglycerin was given in 68 (85%) of 80 procedures. During ablation in the great cardiac vein/anterior interventricular vein, coronary vasospasm occurred in 2 (17%) of 12 patients, which resolved with additional nitroglycerin administration. Right bundle branch block occurred during RVOT ablation in 2 patients (1 transient, 1 permanent). Conclusions Focal PFA provides high acute success and acceptable mid-term efficacy for OT PVCs, with outcomes comparable to contemporary RFA for RVOT and endocardial LVOT sites. Efficacy was lower for left ventricular summit and intramural substrates. Repeat procedures after failed RFA showed particularly favorable results. Coronary vasospasm occurred when PFA was delivered within the great cardiac vein/anterior interventricular vein, suggesting that venous PFA should be considered only after endocardial and alternative mapping/ablation strategies have been exhausted.

BACKGROUND The efficacy and safety of monopolar biphasic focal pulsed field ablation (F-PFA) in close proximity to the atrioventricular (AV) node remain unknown. OBJECTIVE This study aimed to describe the effect of direct or indirect F-PFA application at the AV junction. METHODS In pigs, F-PFA (Centauri, CardioFocus) was applied directly at the AVjunction (n = 3) and indirectly from within the aortic noncoronary cusp (NCC) (n = 5), followed by macroscopic gross and histologic analysis. In 5 patients planned fora pace-and-ablate strategy, F-PFA was applied at the AVjunction. In 1 patient with recurrent para-Hisian atrial tachycardia and previously failed ablation, F-PFA was applied from within the NCC. RESULTS In pigs, direct F-PFA applications at the AVjunction were associated with junctional beats and resulted in complete AV block after 2-3 F-PFA applications. Tissue histology revealed a lesion depth of approximately 8 mm with minor hemorrhage and leukocyte infiltration. F-PFA from within the NCC resulted in a transient increase in the AV node's Wenckebach cycle length and 1 pig had transient AV block, which recovered within 10 minutes. In 5 patients undergoing pace-and-ablate strategy, F-PFA applications at the AVjunction resulted in sustained AV block. In 1 patient, application of F-PFA from within the NCC resulted in termination and noninducibility of a recurrent incessant para-Hisian atrial tachycardia without AV block. There were no immediate or long-term complications. CONCLUSION F-PFA directly at the AVjunction results in nonreversible AV block. F-PFA from within the NCC may represent a promising strategy for treating para-Hisian arrhythmias while preserving AV conduction.

Ablation of ventricular tachycardia is still challenging and has limited efficacy with the traditional thermal energy. Next to its rapidly expanding application in atrial fibrillation (AF) ablation, pulsed field ablation (PFA) may also offer advantages in ablation of ventricular arrhythmias. We conducted a prospective case series involving 5 male patients (mean age: 68±11.5 years) with ischemic cardiomyopathy (ICM) referred for ablation of monomorphic ventricular tachycardia (MMVT), one patient had VT storm despite therapy with amiodarone and left-sided stellate ganglion blockade (SGB). All five patients exhibited reduced left ventricular ejection fraction (EF) <40%. All ablation procedures were performed under deep sedation. Contact force-sensing catheters, high-density diagnostic catheters, and three-dimensional mapping systems were included to generate detailed electro-anatomical maps (EAM). The ablation was conducted using monopolar biphasic focal pulsed field energy (25 Amperes). In all patients, the VT substrates were localized within the left ventricle (LV) (Table 1). Fluoroscopy time and radiation dose were minimal, averaging 1.8±0.7 minutes and 39.4±16.6 µGy/m², respectively. The average procedure duration was 224 ± 89.7 minutes, with an ablation time of 920 ± 494 seconds. In 4 cases, VT was non-inducible at the end of the procedure. In one case (Case 4, characterized by VT storm), we concluded the procedure without testing for VT inducibility due to hemodynamic instability under deep sedation, the necessity for noradrenaline support, and an extended procedural duration (370 minutes). No acute complications related to the procedure were observed. Postprocedural ECG monitoring for 48h showed a stable rhythm without acute recurrence of VT, this was also seen in case 4. Focal PFA for VT in the LV in the context of ICM demonstrates both efficacy and safety. However, further studies are needed to assess long-term outcomes and to better understand the durability and effectiveness of this approach over extended follow-up periods.Table 1

Radiofrequency ablation of outflow (OT) of premature ventricular contractions (PVC) is well established and showed satisfactory acute success with reasonable long term recurrence rates. There is little data regarding PVCs ablation using pulsed field energy. Due to increased transmurality, pulsed field ablation (PFA) may have an advantage in cases of mid- and epimyocardial origins, yet proximity to the coronary arteries may increase the risk of PFA related vasospasms. To assess safety and acute efficacy of focal PFA for OT PVCs A prospective cohort of 35 patients referred for PVC ablation was enrolled. All procedures were performed using the CENTAURI™ System in combination with contact-force sensing catheters and 3D-electroanatomic mapping systems. Acute success was defined as ≥ 80% reduction of the PVC burden during a 24h in-hospital continuous ECG monitoring period. Patients (median age: 65 (IQR: 56, 73) years, 69% males) presented with symptomatic monomorphic (72,5%) or pleomorphic PVCs with a main morphology arising from the OT (28,5%). Acute success was achieved in 88% (31/35) of the cases. The ablation target side was left sided in 60% of the cases, ablation in both ventricles was performed in 31%. The median procedural time was 120 (IQR 90,145) minutes. All procedures were performed fluoroless, unless a coronary angiogram was needed to locate the coronary arteries before ablation in the anterior interventricular vein. On average, eleven applications were delivered to the site of origin. Three of the patients who experienced acute recurrence had a left ventricular origin of their PVCs, while one patient had recurrence of RVOT PVCs. All patients received intravenous (i.v.) nitroglycerine before energy application. In three cases, additional epicardial ablation in the anterior interventricular vein was required, in one patient this additional ablation resulted in acute cessation of the PVCs, while the other two had acute recurrences. During an ablation attempt in the anterior interventricular vein, severe spasm of the left anterior descending artery ensued which quickly recovered after additional administration of i.v. nitroglycerine. No additional complications were encountered. Focal PFA is feasible and quite successful in a cohort of symptomatic patients with OT PVCs. Coronary vasospasm is a possible complication despite nitroglycerine application.

In some cases of atrioventricular nodal reentrant tachycardia (AVNRT), ablation of the slow pathway (SP) at the inferoseptal right-atrium may be ineffective. Some alternative sites for ablation can present distinct challenges and potential complications (e.g. risk of atrioventricular [AV] block with ablation closer to the AV node, ineffective energy delivery due to high impedance and risk for vessel damage with ablation in the coronary sinus [CS]). Methods: We conducted a retrospective analysis of AVNRT ablation cases performed at our center between January 2010 and September 2024. Of 997 patients (619 [62%] female, mean age: 55±15years) who underwent ablation for AVNRT, 107 (10.7%) presented with atypical AVNRT. Following ineffective ablation at the conventional right-sided SP site (R-SP group) in 18 patients (1.8%; 10 female), left-sided SP ablation (L-SP group) via transseptal access was performed in the inferoseptal region of the left atrium. Of these 18 patients, 13 had typical AVNRT, 5 atypical AVNRT. Patients in the L-SP group were older (64±14 vs. 55±15 years; p = 0.01). Procedural times and ablation duration were significantly longer for the L-SP group (186±48 vs. 98±32 minutes; p < 0.001 and 617±129 vs. 181±177 seconds; p < 0.001). For all these patients, the left-sided approach was successful. Left-sided SP ablation of AVNRT via transseptal access is a feasible and effective alternative when conventional right-sided ablation at the typical SP site is unsuccessful.

INTRODUCTION:In patients with atrial arrhythmias originating from the superior vena cava (SVC), the use of radiofrequency energy to isolate the SVC is associated with a significant risk of injury both to the phrenic nerve and the sinus node. Pulsed field ablation (PFA) may overcome the disadvantages of thermal energy and improve both ablation efficacy and safety. OBJECTIVE:We report the feasibility, safety, and clinical efficacy of focal monopolar PFA in patients with the origin of their atrial arrhythmia in the SVC. METHODS:Nine patients (7 men, age 66 ± 8 years) with SVC-induced paroxysmal AF (n = 3), persistent AF (n = 5), or frequent premature atrial beats (n = 1) underwent SVC isolation using focal monopolar PFA. RESULTS:Acute circumferential SVC isolation was achieved in all cases, using 22 Ampere (A) or 25 A in areas with or without phrenic capture, respectively. The safety profile was excellent: two patients had transient sinus arrest and two had transient phrenic nerve stunning. Sinus node and phrenic nerve function recovered during the procedure, and no permanent damage was observed at follow-up. Coronary vasospasm occurred (and quickly resolved after injection of nitroglycerin) in one patient during additional ablation of a focal atrial tachycardia at the coronary sinus ostium. Kidney function remained stable before and after ablation in all patients. CONCLUSIONS:In this patient cohort with SVC-triggered atrial arrhythmia, isolation using focal monopolar PFA was feasible, effective, and safe. No permanent injury to the phrenic nerve or sinus node was observed.

BACKGROUND:Pulsed field ablation (PFA) is a novel technology for catheter-based atrial arrhythmia treatment. Evidence of its application for ventricular arrhythmia ablation is still limited. In this study, we describe the feasibility and efficacy of focal PFA for premature ventricular contraction (PVC) ablation. METHODS:A prospective cohort of 20 patients referred for PVC ablation at 2 centers was enrolled, regardless of the presence of structural heart disease, PVC morphology, or previous ablation attempts. All procedures were performed using the CENTAURI System in combination with contact force sensing catheters and 3-dimensional electroanatomical mapping systems. Energy output and the number of applications were left to the operator's discretion. RESULTS:Eleven (55%) procedures were conducted under general anesthesia, 6 (30%) under deep sedation, and 3 (15%) under light sedation. Muscular contraction was observed in one case (5%). Median procedural and fluoroscopy times were 95.5 and 6.55 minutes, respectively. The median number of PFA applications was 8 with a median contact force of 10g. A statistically significant (76%) reduction was observed in mean peak-to-peak bipolar electrogram voltage before and after ablation (0.707 versus 0.098 mV; P=0.008). Ventricular irritative firing was observed in 11 (55%) patients after PFA. The median follow-up was 120 days. Acute procedural success was achieved in 17 of 20 (85% [95% CI, 0.70-1]) patients. Two of the patients with procedural failure had late success with >80% clinical PVC burden suppression during follow-up, and 2 of 17 patients with acute success had late PVC recurrence, which accounts for a total of 17 of 20 (85% [95% CI, 0.70-1]) patients with chronic success. Transient ST-segment depression occurred in 1 patient, and the right bundle branch block was induced in 2 others (permanently only in one case). CONCLUSIONS:PVC ablation using a focal PFA is feasible, effective, and safe, with promising acute and long-term results in several ventricular locations. Irritative firing is frequently observed. Coronary evaluation should be considered when targeting the outflow tract.

Abstract Aims Pulmonary vein isolation (PVI) often is not sufficient in patients (pts) with persistent atrial fibrillation (AF). Substrate modification (SM) by catheter ablation (CA) of low-voltage zones (LVZ) has yielded favourable results, but those studies were performed before the introduction of contact force (CF) sensing technology. Surgical ablation (SA) studies support the hypothesis that empiric bi-atrial linear ablation (Cox Maze IV procedure) is able to improve success, but there is less data on outcome of patients undergoing left atrial (LA) linear lesions alone. In current guidelines, both CA and SA have Class IIa indication in pts with persistent AF. In this single-centre retrospective study, we analysed the long-term outcomes of CA and SA in pts with persistent AF. Methods and results In the CA group (Figure 1), pts underwent PVI and additional SM in the presence of LVZ (roof line and supero-septal line) using TactiCath™ or SmartTouch™ ablation catheters aiming at contact values ≥10 g < 20 g and FTI >400 g/s. Ablation was performed in a temperature-controlled fashion with energy of 30 W except at the posterior wall (20–25 W). In the SA group (Figure 2), pts underwent ablation procedure (creation of a pure LA endocardial lesion set consistent with the Cox Maze IV) performed by a right mini-thoracotomy approach using the Atricure™ cryoablation probe, a left atrial appendage (LAA) epicardial exclusion using the Atriclip™ system, and mitral valve repair in the presence of severe mitral valve regurgitation. No right atrial lesions were created. 196 pts were included. 120 pts underwent CA [median age: 65 (58–72) years, median LA volume index (LAVI): 66 (56–75) ml/m2], in pts with LVZs PVI + SM was performed [bidirectional block of lines in 100%]. 76 pts underwent SA [median age: 64 (58–74) years, median LAVI 90 (78–103) ml/m2], in 42 pts a mitral valve repair was performed. At 24 months (figure), 89% and 68% of pts were free of AF in the SA and CA group, respectively, mainly without antiarrhythmic drugs (92% SA group and 89% CA group). Conclusions In patients with persistent AF, SA performed by a right mini-thoracotomy approach with linear lesions limited to LA leads to excellent 2-year freedom from AF despite significantly larger LAVI compared with the CA group. LAA epicardial exclusion likely contributed to surgical efficacy by eliminating the LAA as trigger/driver.

BACKGROUND:Pulmonary vein isolation is the cornerstone of catheter ablation in patients with atrial fibrillation (AF). However, with advanced left atrial (LA) structural changes, additional targeted catheter ablation of low-voltage zones (LVZs) has produced favorable results. Therefore, with the advent of single-shot techniques, it would be helpful to predict the presence of LVZs before an ablation procedure.OBJECTIVE:We hypothesized that computed tomography (CT)-derived left atrial volume index (LAVI), in combination with other objective parameters, could be used to develop a score able to predict the presence of LVZs.METHODS:In a large cohort of patients undergoing their first AF ablations, comprehensive echocardiographic evaluations and cardiac CT were performed. During the electrophysiological studies, LA geometry and electroanatomic voltage maps were created. LVZs were defined as areas ≥1 cm2 with bipolar peak-to-peak voltage amplitudes ≤0.5 mV.RESULTS:In a derivation cohort of 374 patients, predictors of LVZs were identified by regression analysis and used to build the Zentralklinik Bad Berka and University of L'Aquila (ZAQ) score (age ≥65 years; female sex; and CT-LAVI ≥57 mL/m2 ). The ZAQ score of 2 points accurately identified the presence and the extent of LVZs (area under the curve [AUC], 0.809; 95% confidence interval [CI], 0.758-0.861; P < .001 and 3 [interquartile range, IQR, 1.5-4.5] vs 7 cm2 [IQR 4-9]; P = .001). In a validation cohort of 103 patients, the predictive value of the score was confirmed (AUC, 0.793; 95% CI, 0.709-0.878; P < .001 and 4 [IQR, 2-7] vs 11.5 cm2 [IQR, 8-16.5]; P = .001).CONCLUSIONS:The ZAQ score identifies LVZs and may be useful for planning the ablation strategy ahead of time.

Introduction: Although pulmonary vein (PV) isolation (PVI) is very effective in paroxysmal atrial fibrillation (AF), in patients (pts) with persistent AF, PVI often is not sufficient. Many studies suggested that low voltage zones (LVZs) outside of the PV might be involved in the complex mechanisms perpetuating AF. However ablation strategies involving substrate modification (SM) did not show additional benefits in persistent AF pts. Those studies were performed before the introduction of contact force technology, and the most likely explanation for these results could be the inability to achieve effective transmural lesions and continuous linear ablation. Hypothesis: We hypothesized that the use of contact force technology would improve ablation efficacy. Therefore, we analyzed the long-term outcome after two different ablation strategies in pts with persistent AF depending on whether there was evidence of LVZs in the left atrium or not. Methods: The presence of LVZs were defined as sites of >3 adjacent low-voltage points <0.5 mV during electrophysiology study. Depending on the location of the LVZ, linear ablation was performed. Catheter ablation was performed using TactiCath™ or SmartTouch™ ablation catheters aiming at contact values ≥10g <20g and FTI >400g/s. Ablation was performed in a temperature-controlled fashion with energy of 30W except at the posterior wall (20-25W). Results: 121 consecutive pts with persistent AF (46 female, median age 66 [59-72] years, mean duration of AF 16 [7-73] months, CT derived LA volume index 66 [56-75]ml/m2) were included: pts without LVZs underwent PVI alone (n = 74), in pts with LVZs, PVI + SM (n = 47) was performed (mitral Isthmus line in 2, supero-septal line in 39, and roof line in 47; bidirectional block was achieved in 100%, 97%, and 100%, respectively). After a median follow-up of 13 [6-21] months, 86% of pts without and 78% with substrate were in sinus rhythm, mainly without antiarrhythmic drugs (89% PVI only, 84% PVI + SM). Conclusions: In patients with persistent AF without LVZs, PVI alone leads to excellent 2-year freedom from AF. In pts with LVZs, additional substrate modification with CF sensing technology is associated with improved success rates compared to previous studies.

Background: In patients with paroxysmal or persistent atrial fibrillation (AF) and diseased left atrium (LA) substrate modification might increase efficacy of pulmonary vein (PV) isolation. LA linear lesions effectively modify the substrate, but have been largely abandoned because bidirectional block at the mitral isthmus (MIL, left inferior PV to mitral annulus) is difficult to achieve. We therefore aimed to compare safety, acute and mid-term efficacy of MIL vs. an alternative superoseptal line (SSL, right superior PV to mitral annulus). Methods and Results: patients were alternatively assigned to MIL or SSL in addition to PV isolation and linear ablation at the LA roof and at the cavotricuspid isthmus. Conventional criteria were used to confirm bidirectional block. Seventy patients [median 64 years, 84% persistent and 16% ≥48hours episodes of long paroxysmal AF] were enrolled. Bidirectional block was achieved in 94% of MILs vs. 83% of SSLs (P = .2595). Most (5/6) failed SSLs occurred in the first half of the study period. All PVs were isolated, bidirectional block was 96% and 100% at the LA roof and cavotricuspid isthmus. No difference in procedural or complication rate was found. At follow-up, a trend toward better success rate was found for the SSL (86% vs. 74%; P = .2293). Conclusion: After completion of a short learning curve, the SSL is a good alternative, showing equal safety/acute efficacy and a trend for better midterm success rates.

Aims:The clinical characteristics of atrial tachycardias (AT) ablated from the non-coronary aortic sinus (NCS) are thus far described only in small series. We aimed to outline, in a large cohort of patients, the clinical, electrocardiographic, electrophysiological characteristics of this tachycardia.Methods and results:We analysed data pertaining to clinical, electrocardiographic, and electrophysiological characteristics of 43 consecutive patients from an overall cohort of 441 with AT who were successfully ablated from the NCS. The tachycardias ablated from the NCS were paroxysmal (98%) and adenosine sensitive (35/35). The patients were aged 54.6 ± 12.4 years, showing female preponderance (74%). No P wave pattern was predictive of the location of ablation. Electrophysiological findings suggested a possible micro-reentrant mechanism. During tachycardia, atrial electrograms recorded in the NCS preceded the A in the His region by 10.9 ± 7.4 ms. Fractionated atrial electrograms were noted at the site of ablation in 42 patients during the tachycardia. Radiofrequency ablation terminated the tachycardia within 5 s in 88%, with thermal automaticity seen only in 3 patients. The site of ablation at the base of the NCS was adjacent to the presumed site of the retroaortic node, a remnant of the initial atrio-ventricular canal musculature.Conclusions:AT ablated from the NCS is a paroxysmal arrhythmia in middle-aged women, with distinct electrocardiographic and electrophysiological characteristics. We suspect the retroaortic node to be involved in the tachycardia circuit.

Catheter ablation of para-Hisian premature ventricular contractions (PVCs) still represents a challenge and is a compromise between success and inadvertent AV block. We describe a possible strategy to address PVCs from this location with high-amplitude His-bundle potentials at the site of earliest activation.

Introduction: techniques aiming at reducing X-Ray exposure in patients undergoing catheter ablation (CA) are of great importance. Aim of this study was to compare the dose area product (DAP, microgray, µGy/m2) and the equivalent dose (ED, milliSieverts, mSv) during CA of paroxysmal or persistent atrial fibrillation (AF) before and after the meticulous implementation of measures to reduce X-Ray exposure (especially careful use of collimation and frame rate reduction). Methods: X-ray exposure, procedural and parameters were compared in the 2 groups of consecutive patients with paroxysmal and persistent AF undergoing CA with the use of a 3D-Mapping System before (High Dose) and after (Low Dose, since 11/2012) the introduction of a strict radiation reduction protocol. Results: between 01/2010 and 10/2015, 870 patients [62 (55,69) years old, 352 (40%) female, 405 (46%) paroxysmal AF, 261 (30%) recurrent AF after previous procedure] underwent CA with the Ensite Velocity (739, 85%) or Carto3 (131, 15%) 3D-Mapping Systems. Slightly larger left atrial volumes were observed in the “low dose” group, other clinical and procedural characteristics were well matched between groups. The dose area product and equivalent were significantly (P = .0000) reduced by 60% for both paroxysmal (DAP 1549 (1032, 2814) vs. 4195 (2521, 6687) µGy/m2 and ED 3.1 (2.1, 5.6) vs. 8.4 (5.0, 13.4) mSv) and persistent (DAP 2300 (1481, 3434) vs. 5605 (3563, 9160) µGy/m2 and ED 4.6 (2.9, 6.9) vs.11.2 (7.1, 18.3) mSv) with careful setting of the fluoroscopy. Conclusion: Careful use of collimation and frame rate reduction leads to a significant decrease in X-Ray exposure during CA for AF.