Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry.

AIMS: Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons. METHODS: This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023. RESULTS: Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB. CONCLUSIONS: Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

Phrenic nerve injury after atrial fibrillation ablation: different recovery courses among cryoballoon, laser balloon, and radiofrequency ablation.

BACKGROUND: Phrenic nerve injury (PNI) is one of the common complications in atrial fibrillation (AF) ablation, which often recovers spontaneously. However, the course of its recovery has not been examined fully, especially in regard to the different ablation methods. We sought to compare the recovery course of PNI in cryoballoon, laser balloon, and radiofrequency ablation. METHODS: This multicenter retrospective study analyzed 355 patients who suffered from PNI during AF ablation. PNI occurred during cryoballoon ablation (CB group) and laser balloon ablation (LB group) for a pulmonary vein isolation in 288 and 20 patients, and radiofrequency ablation for a superior vena cava (SVC) isolation (RF-SVC group) in 47 patients, respectively RESULTS: There was a significant difference in the estimated probability of PNI recovery after the procedure between the methods (p = 0.01). PNI recovered significantly earlier in the CB group, especially within 24 h and 3 months post-procedure (the percentage of the recovery within 24 h and 3 months: 49.7% and 71.5% in the CB group, 15.0% and 22.2% in the LB group, and 23.4% and 41.9% in the RF-SVC group, respectively). Persistent PNI after 12 months was observed in only seven patients in the CB group, one in the LB group, and four in the RF-SVC group, respectively. CONCLUSION: PNI rarely persists over 12 months after AF ablation; however, there is a difference in the timing of its recovery. PNI recovers quicker with cryoballoon ablation than with laser balloon ablation or radiofrequency ablation of the SVC.

Initial clinical experience with the novel POLARx FIT cryoballoon system for pulmonary vein isolation in patients with atrial fibrillation.

Background: The POLARx FIT system (Boston Scientific, MA, USA) is a novel cryoballoon (CB) ablation technology in which the balloon diameter can be expanded from 28 to 31 mm. The aim of this study was to compare the benefits and safety of the new POLARx FIT system to those of the existing POLARx system currently in use for pulmonary vein (PV) isolation (PVI) in patients with atrial fibrillation. Methods: The first 70 consecutive patients who underwent CB-based PVI with the POLARx FIT system were retrospectively compared with 200 consecutive patients treated with the POLARx system at Sakakibara Heart Institute from October 2021 to May 2023. Results: The POLARx FIT system yielded a higher mean ± standard deviation nadir temperature in the right inferior PV (-59.2 ± 5.29 °C vs. - 62.0 ± 5.08 °C, p = 0.006), but this required a balloon size reduction to 28 mm in 30 % of cases. No significant differences were detected in the time to isolation and thaw time of any PV between the two groups. After the CB-based PVI procedure, no residual PV carina potentials were observed with the POLARx FIT system, whereas 4/20 were with the POLARx system (p = 0.04). Conclusions: The POLARx FIT system had comparable effectiveness and safety to the basic POLARx system. This technology may improve the ablation area, including the PV carina. However, the 31-mm balloon alone was not sufficient to isolate certain PVs.

Acute procedural efficacy and safety of a novel expandable diameter cryoballoon in atrial fibrillation ablation: Early results from a multicenter ablation registry.

INTRODUCTION: The major limitation of the current cryoballoon (CB) system is a fixed 28 mm balloon-size. We sought to analyze real-world early experience with novel-sized adjustable CB. METHODS: This multicenter observational study included 140 consecutive atrial fibrillation patients (71 years, 94 men, 86 paroxysmal) who underwent pulmonary vein (PV) isolation using expandable diameter CB capable of ablation at 28 or 31 mm. RESULTS: Out of 544 targeted PVs, 526 (96.7%) were successfully isolated by a size-adjustable CB with a 770 [690-870] second median application dose, while the remaining 18 required touch-up ablation. Among them, 326 (62.0%) PVs were isolated by a 31 mm balloon, and the rate was significantly higher for upper than lower PVs (73.0% vs. 45.7%, p < .0001) and highest for right superior (78.5%) and lowest for right inferior (39.9%) PVs. The biophysical parameters and time to isolation were comparable between the 28 and 31 mm balloons, however, the real-time PV potential monitoring capability was significantly higher for 31 mm than 28 mm balloons for the left superior PV. The esophageal temperature reached 15°C during left inferior PV ablation significantly more often with 31 mm than 28 mm balloons (43.1% vs. 18.2%, p = .008). Right phrenic nerve injury (PNI) occurred in 9 (6.4%) patients during applications (6 right superior, 2 right inferior PVs), and most occurred with a 31 mm balloon. CONCLUSIONS: Our real-world early data demonstrated high acute efficacy and safety of the novel-sized adjustable CB. The biophysical parameters were similar between the 28 and 31 mm balloons. No marked decrease in the incidence of PNI was observed even with 31 mm balloons.

Characteristics of two different cryoballoon systems for treatment of paroxysmal atrial fibrillation: study protocol for a multicenter randomized controlled trial (CONTRAST-CRYO Trial).

BACKGROUND: Single-shot pulmonary vein isolation (PVI) utilizing cryothermal energy is an effective and safe treatment for atrial fibrillation (AF) patients. A novel cryoballoon system, POLARx™, has been recently introduced. The aim of this study was to compare the efficacy, safety, and biophysical parameters of PVI between the novel cryoballoon system, POLARx™, and the standard cryoballoon system, Arctic Front Advance Pro™ (AFA-Pro), in patients with paroxysmal AF. METHODS: The CONTRAST-CRYO trial is a prospective, multicenter, open-label, randomized controlled study performed at seven large cardiac centers. This study was approved by the central ethics committee or the local ethics committee of each participating hospital and has been registered at UMIN Clinical Trials Registry (UMIN000049948). The trial will assign 200 patients with paroxysmal AF undergoing PVI to POLARx™ and AFA-Pro in a 1:1 randomization. The primary endpoint is the one-shot acute success rate of the right inferior pulmonary vein. Second endpoints include freedom from documented atrial fibrillation, atrial flutter, or atrial tachycardia without antiarrhythmic drugs at 12 months after the procedure, freedom from re-do procedures, the incidence of procedure-related adverse events, freezing duration, and the biophysical parameters during applications for each PV, total procedure and fluoroscopy time, and PVI durability during re-do procedures. CONCLUSION: The CONTRAST-CRYO trial is a prospective, multicenter, randomized study designed to elucidate the difference in the efficacy, safety, and biophysical parameters between POLARx™ and AFA-Pro in paroxysmal AF patients undergoing PVI. The findings from this trial may provide a valuable indication for selecting the optimal cryoballoon system. CLINICAL TRIAL REGISTRATION:  UMIN000049948.

Adjunctive posterior wall isolation for the treatment of persistent and longstanding persistent atrial fibrillation (CORNERSTONE AF) trial: Design and rationale.

BACKGROUND: A left atrial posterior wall isolation (LAPWI) is one of the atrial fibrillation (AF) ablation strategies. HYPOTHESIS: We hypothesized that an additional empirical LAPWI would increase the freedom from recurrent atrial arrhythmias as compared to standard AF ablation in persistent AF patients. METHODS: The CORNERSTONE AF study is a prospective, randomized, multicenter study investigating patients with AF persisting for >7 days and <3 years undergoing first-time AF ablation. They will be randomized to pulmonary vein isolation (PVI) or PVI + LAPWI in a 1:1 manner. Although PVI can be performed with either radiofrequency catheters or cryoballoons, only radiofrequency catheters will be permitted to achieve LAPWIs. Additional focal ablation targeting non-pulmonary vein triggers will be allowed. A total of 516 patients will be enrolled in 17 centers between August 2022 and February 2024 based on the calculation with 80% power, considering the assumption that 65% and 75% of the PVI and PVI + LAPWI group patients will be free from atrial arrhythmia recurrence 18-months postprocedure (10% of dropout). The primary endpoint is freedom from documented atrial arrhythmias 18 months postsingle procedures. Clinical follow-up will include 7-day ambulatory electrocardiograms and routine outpatient consultations by electrophysiologists at 1, 3, 6, 9, 12, and 18 months postprocedure. RESULTS: As of August 2023, a total of 331 patients (68 ± 9 years, 270 men, 43 longstanding persistent AF) have been enrolled. CONCLUSIONS: The CORNERSTONE AF study is a prospective, randomized, multicenter trial designed to evaluate the efficacy and safety of an adjunctive empirical LAPWI following standard AF ablation in persistent AF patients.

Inappropriate shock incidence in patients with subcutaneous implantable cardioverter-defibrillators with concomitant cardiac implantable electronic devices: A single-center cohort study.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICDs) are occasionally used in combination with other cardiac implantable electronic devices (CIEDs). However, whether the incidence of inappropriate shock increases in patients with S-ICDs and concomitant CIEDs remains unclear. This study aimed to investigate the association between the concomitant use of CIEDs and the incidence of inappropriate shock in patients with current-generation S-ICDs. METHODS: A total of 127 consecutive patients received an S-ICD. Patients were assigned to two groups depending on concomitant use of CIEDs at the time of S-ICD implantation: patients without other CIEDs (non-combined group, 106 patients) and patients with other CIEDs (combined group, 21 patients). CIEDs included pacemakers, implantable cardioverter defibrillators, cardiac resynchronization therapy pacemakers, and cardiac resynchronization therapy defibrillators. The primary outcome was inappropriate shock, defined as a shock other than ventricular arrhythmia. Hazard ratios and 95% confidence intervals were calculated using a time-varying Cox proportional hazards model which was adjusted for age because age differed between the groups and could be a confounder. RESULTS: During a median follow-up period of 2.2 years (interquartile range, 1.0-3.4 years), inappropriate shock events occurred in 17 (16%) and five (19%) patients of the non-combined and combined groups, respectively. While the age-adjusted hazard ratio for inappropriate shock was 24% higher in the combined than in the non-combined group (hazard ratio = 1.24, 95% confidence interval, 0.39-3.97), this difference was insignificant (p = .71). CONCLUSION: The incidence of inappropriate shock did not differ between patients with and without concomitant use of CIEDs, suggesting that S-ICDs could potentially be combined with other CIEDs without increasing the number of inappropriate shocks. Further studies are warranted to confirm the safety and feasibility of concomitant use of S-ICDs and CIEDs.

Symptomatic periesophageal vagal nerve injury by different energy sources during atrial fibrillation ablation.

Background: Symptomatic gastric hypomotility (SGH) is a rare but major complication of atrial fibrillation (AF) ablation, but data on this are scarce. Objective: We compared the clinical course of SGH occurring with different energy sources. Methods: This multicenter study retrospectively collected the characteristics and clinical outcomes of patients with SGH after AF ablation. Results: The data of 93 patients (67.0 ± 11.2 years, 68 men, 52 paroxysmal AF) with SGH after AF ablation were collected from 23 cardiovascular centers. Left atrial (LA) ablation sets included pulmonary vein isolation (PVI) alone, a PVI plus a roof-line, and an LA posterior wall isolation in 42 (45.2%), 11 (11.8%), and 40 (43.0%) patients, respectively. LA ablation was performed by radiofrequency ablation, cryoballoon ablation, or both in 38 (40.8%), 38 (40.8%), and 17 (18.3%) patients, respectively. SGH diagnoses were confirmed at 2 (1-4) days post-procedure, and 28 (30.1%) patients required re-hospitalizations. Fasting was required in 81 (92.0%) patients for 4 (2.5-5) days; the total hospitalization duration was 11 [7-19.8] days. After conservative treatment, symptoms disappeared in 22.3% of patients at 1 month, 48.9% at 2 months, 57.6% at 3 months, 84.6% at 6 months, and 89.7% at 12 months, however, one patient required surgery after radiofrequency ablation. Symptoms persisted for >1-year post-procedure in 7 patients. The outcomes were similar regardless of the energy source and LA lesion set. Conclusions: The clinical course of SGH was similar regardless of the energy source. The diagnosis was often delayed, and most recovered within 6 months, yet could persist for over 1 year in 10%.

Initial multicenter clinical experience with the first-generation endoscopic guided laser balloon in Japan.

BACKGROUND: Isolation of the pulmonary veins (PVs) is the golden standard for atrial fibrillation (AF) ablation. To achieve a permanent PV isolation, the endoscopic guided HeartLight laser balloon system was invented. We analyzed the safety and efficacy of this laser balloon system. METHODS AND RESULTS: Three hundred four patients from 21 investigational sites inside Japan were enrolled in this study. One thousand sixty-two out of 1175 PVs (90.4%) were isolated using the HeartLight laser balloon. The isolation rate of the left superior, left inferior, right superior, and right inferior PVs was 87.8%, 91.3%, 91.6%, and 92.1%, respectively. The procedure time, defined as the time from the venous access to taking out the balloon, was 155 ± 39 min. The fluoroscopic time was 44 ± 25 min. The mean follow-up period was 309 ± 125 days. The freedom from AF recurrence at 3 months was 89.0% and at 12 months 82.1%. Adverse events occurred in 22 patients (7.2%) including phrenic nerve injury lasting more than 3 months in 1.6% and strokes in 1.0% of the patients. CONCLUSIONS: This initial experience demonstrated that the laser balloon ablation was feasible for PV isolation in Japanese AF patients.

Spatial relationship of localized sources of persistent atrial fibrillation identified by a unipolar-based automated algorithm to complex fractionated atrial electrocardiograms and atrial low voltage areas.

INTRODUCTION: Spatial characteristics of localized sources of persistent atrial fibrillation (AF) identified by unipolar-based panoramic mapping software (CARTOFINDER) remain unclear. We evaluated spatial characteristics of bi-atrial AF localized sources in relation to complex fractionated atrial electrocardiograms (CFAEs) and atrial low voltage area (LVAs) (≤0.35 mV during AF). METHODS AND RESULTS: Twenty consecutive patients with persistent AF underwent bi-atrial voltage, CFAE, and CARTOFINDER mapping before the beginning of ablation (18 [90%] patients, initial procedure; 2 [10%] patients, repeat procedure). CFAEs were recorded using the interval confidence level (ICL) mode and defined as sites with a confidence level of ≥80% of maximal ICL number. We elucidated the following: (1) differences in the rate of AF localized sources and CFAEs inside or outside the atrial LVAs; (2) distribution of AF localized sources and CFAEs; and (3) distance between the closest points of AF localized sources and CFAEs. A total of 270 AF localized sources and 486 CFAEs were identified in 20 patients. AF localized sources were confirmed more often outside atrial LVAs than CFAEs (71% vs. 46% outside LVA, p < .001). AF localized sources and CFAEs were diffusely distributed without any tendency in bi-atria. Mean distance between closest AF localized sources and CFAEs was 22 ± 8 mm. CONCLUSION: AF localized sources identified by CARTOFINDER are different therapeutic targets as compared to CFAEs and could be confirmed both inside and outside atrial LVAs.

Efficacy of SubcutAneous implantable cardioVErter-defibrillators in ≤18 year-old CHILDREN: SAVE-CHILDREN registry.

BACKGROUND: In adult patients, subcutaneous implantable cardioverter defibrillators (S-ICDs) have been reported to be non-inferior to transvenous ICDs with respect to the incidence of device-related complications and inappropriate shocks. Only a few reports have investigated the efficacy of S-ICDs in the pediatric field. This study aimed to investigate the utility and safety of S-ICDs in patients ≤18 years old. METHODS: This study was a multicenter, observational, retrospective study on S-ICD implantations. Patients <18 years old who underwent S-ICD implantations were enrolled. The detailed data on the device implantations and eligibility tests, incidence of appropriate- and inappropriate shocks, and follow-up data were assessed. RESULTS: A total of 62 patients were enrolled from 30 centers. The patients ranged in age from 3 to 18 (median 14 years old [IQR 11.0-16.0 years]). During a median follow up of 27 months (13.3-35.8), a total of 16 patients (26.2%) received appropriate shocks and 13 (21.3%) received inappropriate shocks. The common causes of the inappropriate shocks were sinus tachycardia (n = 4, 30.8%) and T-wave oversensing (n = 4, 30.8%). In spite of the physical growth, the number of suitable sensing vectors did not change during the follow up. No one had any lead fractures or device infections in the chronic phase. CONCLUSIONS: Our study suggested that S-ICDs can prevent sudden cardiac death in the pediatric population with a low incidence of lead complications or device infections. The number of suitable sensing vectors did not change during the patients' growth.

Cephalic vein cut-down technique for severe venous spasm following axillary vein puncture at pacemaker implantation.

An 83-year-old male with complete atrioventricular block underwent dual-chamber pacemaker implantation. Venography showed normal anatomy of the left axillary vein. Following sedation with intravenous propofol, local anesthesia, and skin incision, we punctured the left axillary vein on the first limb. However, the guidewire could not be advanced despite blood backflow after the initial puncture. On venography, left axillary vein on the first limb totally disappeared with dilated collaterals. We diagnosed axillary vein spasm and injected 1000 µg of intravenous nitroglycerin. After 15 min, repeated venography showed slight contrast flow in the axillary vein. We alternatively punctured the axillary vein on the second limb. However, the axillary vein was spasmodically occluded again. We considered the possibility that puncture of the right axillary vein could also result in venous spasm. Since the left cephalic vein was identified after waiting time, we partially cut down the left cephalic vein and inserted guidewires into the vein. The ventricular and atrial leads were successfully implanted through sheaths in the right ventricular septum and right atrial appendage, respectively. Learning objective: Pacemaker implantation complicated with puncture-related axillary vein spasm is challenging. Severe venous spasms refractory to waiting time or nitroglycerin sometimes require conversion of access site. However, the bail-out technique from ipsilateral access remains unclear. Cut-down technique of the ipsilateral cephalic vein is one alternative to manage severe axillary vein spasm refractory to nitroglycerin and waiting time.

Short-time ventricular tachycardia ablation for cardiac sarcoidosis using coherent map.

A 69-year-old woman with isolated cardiac sarcoidosis was hospitalized for frequent appropriate implantable converter defibrillator therapies for ventricular tachycardia (VT) despite of favorably controlled condition with oral prednisolone. The patient underwent urgent catheter ablation with CARTO 3D mapping system. Although the voltage map, activation map, and propagation map during VT could not visualize the tachycardia circuit, the coherent map clarified entrance and exit sites of the tachycardia circuit with slow or nonconducting (SNO) zones, which seemed like a figure-of-eight circuit. Considering the risk of VT termination or acceleration to rapid unstable VT, neither entrainment nor pacing studies were performed. The VT was terminated near the exit site of the isthmus where tiny pre-systolic potential was detected. Any diastolic potentials could not be detected. This meant that the critical isthmus might be located at the epicardium or deep incite of the left-ventricular myocardium where the coherent map showed as SNO zones. We should recognize coherent map as artificial that may represent VT circuit as if complete endocardial reentry even if not. The procedural time from mapping to termination of VT was only 22 minutes. The patient has been free from any cardiovascular events after the procedure. Coherent map might be feasible for revealing the critical isthmus of hemodynamically stable VTs without using electrophysiological techniques, including entrainment, pacing study, and voltage map during own beats, and would enable us to achieve successful VT ablation in a short time.

Radiofrequency Current Versus Balloon-Based Ablation for Atrial Fibrillation.

The basis for selection of contemporary ablation technologies for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remains unclear. We compared procedural data and efficacy in a propensity score-matched cohort treated with 4 ablation technologies in a center mainly using cryoballoon (CB). A total of 819 consecutive patients with AF underwent PVI, using radiofrequency current (RFC) (65 patients), CB (693 patients), hot balloon (HB) (74 patients), and laser balloon (LB) (52 patients). Fifty patients (82% paroxysmal AF) were selected from each group according to the propensity score. Procedural data and freedom from atrial tachyarrhythmia recurrence after the index procedure were compared. All pulmonary veins were isolated in all groups. Procedure time was shorter in CB and HB groups (RFC: 148 ± 53 vs CB: 85 ± 37 vs HB: 102 ± 31 vs LB: 140 ± 28 minutes, p <0.001). RFC touch-up was most commonly required for PVI in the HB group among balloon groups (40%) (p <0.001). Total complication rate was 4% to 18% without any statistical differences between groups (p = 0.123). Phrenic nerve injury occurred most often in the CB group (16%) (p <0.001). During a mean follow-up of 21 ± 6 months, there were no significant differences among groups for freedom from atrial tachyarrhythmia recurrence after the index procedure (RFC: 68% vs CB: 78% vs HB: 76% vs LB: 76%, p = 0.440). In conclusion, all the ablation technologies facilitate safe and efficient PVI, with slight differences in the procedural data and complications.

Efficacy of left atrial posterior wall isolation guided by lesion size prediction module for non-paroxysmal atrial fibrillation.

AIMS: The efficacy of left atrial posterior wall isolation (PWI) is controversial. Lesion durability may be a major cause of arrhythmia recurrence. The use of the lesion size prediction module improves lesion durability. This study aimed to compare the clinical outcomes of pulmonary vein isolation (PVI) alone and PWI in addition to PVI (PVI + PWI) in patients with non-paroxysmal atrial fibrillation (AF) using a lesion size prediction module. METHODS AND RESULTS: This study is a sub-analysis of the recently published prospective multicentre observational study called ALCOHOL-AF (association of alcohol consumption with outcome of catheter ablation of AF). In this sub-analysis, patients with non-paroxysmal AF in whom PVI alone or PVI + PWI was performed using the lesion size prediction module were included. Freedom from atrial tachyarrhythmia was compared between PVI alone and PVI + PWI groups using propensity score analyses. Of the 3474 patients registered in the ALCOHOL-AF study, 572 patients (age 65.6 ± 10.1 years, male 77.4%, longstanding persistent AF 25.5%) were included in this sub-analysis. We selected 212 patients treated with PVI alone and 212 treated with PVI + PWI using one-to-one propensity score matching. During the follow-up period, atrial tachyarrhythmia recurrence was documented in 92 (43.4%) and 50 (23.6%) patients in the PVI alone and PVI + PWI groups, respectively. Freedom from atrial tachyarrhythmia recurrence without anti-arrhythmic drugs after a single procedure was significantly higher in PVI + PWI than in PVI alone groups (hazard ratio: 0.452, 95% confidence interval: 0.308-0.664, P < 0.001). CONCLUSION: In this hypothesis-generating study, lesion size prediction module-guided PVI + PWI was associated with better clinical outcomes than PVI alone in patients with persistent or longstanding persistent AF.