Ablation Time Research Articles

Impact of the underlying rhythm during cavotricuspid isthmus ablation on the incidence of future new-onset atrial fibrillation: insights from an international multi-centre registry

Abstract Background Radiofrequency catheter ablation of the cavotricuspid isthmus (RF-CTI) is the estabslished treatment of typical atrial flutter (AFL). After RF-CTI for AFL patients without previously documented atrial fibrillation (AF) may also develop AF. It is unknown whether the presence or absence of AFL at the time of ablation can predict the future occurence of AF. Purpose To compare baseline characteristics, procedural data, and long-term follow-up (FU) of patients with AFL. Methods Consecutive patients with documented AFL undergoing RF-CTI were enrolled in a multi-center registry in five centers in two countries between February 2017 and July 2023. For patients with AFL, entrainment mapping was performed for confirming CTI dependent AFL. Patients were categorized into two groups, those with AFL and those with sinus rhythm (SR) during RF-CTI. FU data were collected, including clinical assessments, 12-lead electrocardiogram (ECG) and 24-hour Holter-ECGs during each visit. Results Of the 949 subjects, 36% were excluded from the analysis due to a history of AF. A total of 574 patients were included (mean age 68 +/- 11 yrs, 14% females), 62% presented in AFL group and 38 % SR group during CTI. Median FU was 364 days. Patients in AFL group were older (P < 0.029), more likely to have diabetes (P = 0.026), and were less frequently treated with antiarrhythmic drugs (P < 0.001). In the first 12 months of FU, 40% of the patients underwent three FU examinations, while 77% of the patients underwent at least one 24-hour Holter-ECGs during FU. In the Kaplan-Meier analysis patients in AFL group significantly less often developed AF during FU (log-rank, P < 0.016, central ). In the multivariate Cox regression analysis, sinus rhythm during ablation (hazard ratio 1.474; 95% CI 1.043-2.084; P = 0.028), male gender (hazard ratio 1.722; 95% CI 1.116-2.658; P = 0.014) and coronary artery disease (hazard ratio 1.711; 95% CI 1.145-2.555; P = 0.009) were identified as predictors for the occurence of AF during FU. Conclusion Over a one year follow-up, new onset AF occurs significantly less frequently in patients with ongoing atrial flutter during RF-CTI ablation.

A multi-center retrospective cohort analysis of age and racial disparities in patients undergoing repeat ablation for recurrent atrial fibrillation

Abstract Introduction Atrial fibrillation (AF) is the most common type of cardiac arrhythmia, and its prevalence has been increasing worldwide. Current data shows that AF is more common in white males compared to blacks despite blacks having multiple cardiovascular comorbidities. There is paucity of data showing the recurrence of AF re-ablation after index ablation specifically as it pertains to race, gender, and age. We sought to explore the rates of recurrent AF re-ablation in this retrospective cohort analysis. Methods Using a multi-center database, we examined 23,558 encounters and 10,530 had readmission records i.e. readmitted within 3 years. The encounters included adults (18+) who had an ablation procedure for atrial fibrillation between 1/1/2018-06/30/2020. We used binary logistic regression models and Tukey-Kramer procedure to analyze pairwise comparisons among different subgroups of race, sex, and age group. The primary endpoint was recurrence of repeat ablation. Secondary endpoints included non-fatal stroke and myocardial infarction. Results Our sample size was 23,558 patients, 20,276 were white patients (86%) and 3,282 were non-white patients (14%). The average age was 66.29 years (SD 10.43) and average age at the time of repeat ablation was 65.97 years. The average BMI was 21.55. Out of the 23,558 patients, 14.30% (N= 3368) had re-ablation within 3 years of the index ablation. The odds ratio of re-ablation for patients in their 50s is 1.4229 (95% CI [1.1172, 1.8122]) compared to patients in their 80s. Similarly, the odds ratio is 1.4330 (95% CI [1.1466, 1.7909]) for the 60-69 group, 1.3075 (95%CI [1.0458, 1.6346]) for the 70-79 group and 1.3443 (95% CI [1.0088, 1.7914]) for patients below 50 compared to over 80 group. The LR for re-ablation was 0.8438 (p=0.3583) in females. The incidence of non-fatal stroke and MI were 0.27% (N= 63) and 0.19% (N= 45). Average length of time to re-ablation was 415.5 days. Discussion When controlling for age group and sex, race was not significantly associated with an increased likelihood of repeat ablation. When controlling for race and age group, sex was not significantly associated with an increased likelihood of repeat ablation. When controlling for race only, females were not at a higher risk of re-ablation. However, when controlling for race and sex, patients in their 50s are 42.3% more likely to have re-ablation when compared to patients in their 80s. In contrast, the age of patients at their first ablation increased, there appeared to be a rising trend indicating a higher chance of AF recurrence within 3 years when controlling for race and sex. Conclusion The incidence of repeat AF ablation is not higher in racial minorities when compared to whites. Interestingly, there appears to be an decreasing rate of AF re-ablation in older patients despite a higher rate of AF recurrence as age increases possibly owing to more conservative therapeutic approach such as medical management.

Evaluating lesion integrity with diamond temp system

Abstract Background Pulmonary vein (PV) isolation by temperature-controlled (TC) radiofrequency ablation (RFA) is regaining popularity due to tissue-temperature feedback from thermocouples attached at the distal tip. The Diamond Temp (DT) ablation catheter system is uniquely able to monitor real time tissue temp during RFAs. The DT catheter tip has a 1.1 mm split tip electrode, allowing precise bipolar pacing during RFA. Loss of capture (LOC) with High output pacing (HOP) has been considered a surrogate to assess lesion transmurality [1]. This study evaluated the utility of DT catheter distal pacing to achieve durable lesions. Standard guidelines for TC ablation recommend achieving target tissue-temperature of 60ºC to produce durable lesions. The purpose of this study was to assess whether LOC is achieved at target tissue-temperature of 60ºC. Objective Pacing during ablation from distal tip micro electrode of the DT catheter and observing the time it takes for LOC at different segments around pulmonary veins. First pass isolation (FPI) percentage was also collected. Methods While target enrollment for this prospective study is 50 patients, these preliminary findings are based on analysis of the first 15 patients enrolled, all of whom had symptomatic, drug-refractory paroxysmal AF. Point-by-point RF lesions were delivered around ipsilateral PVs, divided into 4 segments: superior, inferior, anterior, and posterior. Ablation was performed in a TC mode with max temp setting of 60°C and max power of 50 watts. HOP was performed prior to start of ablation and discontinued once LOC was observed. Time taken to LOC around all 4 segments of PVs were recorded. Intracardiac echocardiography (ICE) was used to guide contact and monitor lesion formation. Results Overall mean time to LOC was 3.32 sec. Anterior sites exceeded this mean. Inferior, superior, and posterior sites generally had shorter times. 92.53% of locations achieved LOC within 2-5 sec of ablation. The right anterior PV had the longest time at 3.73 sec, exceeding the overall mean of 3.32 sec. All patient achieved FPI. Conclusion Reaching target therapeutic temp of 60°C alone may not be sufficient to achieve LOC around PVs. Ablation duration of 4 sec led to LOC in 92.53% of lesions. Certain anatomical regions like anterior locations required prolonged ablation time. Tissue thickness on ICE correlated directly with time required to LOC. This analysis shows that TC ablation with DT is effective; however, a therapeutic stable temperature of 60°C for at least 4 sec may be needed to achieve durable lesions around PVs. Tissue thickness on ICE and stability of temperature appear to be independent variables affecting duration prior to LOC.

Trans-femoral transcatheter intramyocardial septal radiofrequency ablation: a novel therapeutic approach for obstructive hypertrophic cardiomyopathy

Abstract Background Septal reduction techniques play a pivotal role in mitigating morbidity and mortality among patients with obstructive hypertrophic cardiomyopathy (oHCM). While trans-apical intramyocardial septal radiofrequency ablation (PIMSRA or LIWEN procedure) has shown promise in reducing left ventricular outflow tract (LVOT) gradients and improving symptoms in oHCM patients, it is associated with complications such as cardiac tamponade and atrioventricular block. Objective This study introduces a novel approach for transcatheter radiofrequency ablation of hypertrophic septum via femoral access, utilizing the DragonFire Transcatheter Myocardial Puncture and Radiofrequency Ablation System. We aim to evaluate its safety and medium-term outcomes in patients with oHCM. Methods A prospective, single-center, single-arm study of tf-PIMSRA was conducted in patients with drug-refractory oHCM. Ten patients were enrolled and underwent the procedure under the guidance of transesophageal echocardiography. The primary outcome was 30-day major adverse clinical events, with secondary outcomes including 90-day improvements in outflow obstruction and quality of life. Results All patients, with an average age of 57±10 years, including 4 males, underwent the procedure successfully without any complications, including major adverse clinical events or conduction abnormalities. The average duration of the procedure was 125.2±34.6 minutes, with an average ablation time of 38.69±18.29 minutes and ablation energy of 3.60±1.49KJ. At 90-day follow-up, significant reductions were observed in peak LVOT gradients (resting gradient: from 82.00 [56.00] mmHg to 14.00 [6.25] mmHg; p < 0.001; provoked gradient: from 102.00 [76.25] mmHg to 33.00 [16.50] mmHg; p = 0.002), and interventricular septum thickness (from 22.00 [19.00] mm to 17.00 [15.00] mm; p = 0.002). These improvements were associated with enhancements in NYHA functional classification (from 3.00 [2.75] to 1.00 [1.00]; p < 0.0001), Kansas City Cardiomyopathy Questionnaire scores (from 59.00 [44.50] to 80.00 [77.25]; p < 0.02), 6-minute walk distance (from 441 [400] m to 480 [465] m; p < 0.01), and pro B-type natriuretic peptide levels (from 1738.00 [1113.25] pg/ml to 252.00 [200.00] pg/ml; p = 0.002). All patients achieved New York Heart Association functional class I or II at follow-up. Conclusions Transfemoral PIMSRA appears to be a safe and effective procedure for relieving LVOT obstruction and symptoms in patients with drug-refractory oHCM. These findings support further investigation through randomized clinical trials comparing it with established septal reduction therapies.Patient-Level Outcomes for the trans-fem

Accuracy of a non-invasive mapping system for the localisation of re-entrant VT site of origin and its relationship to myocardial scar on cross-sectional imaging

Abstract Introduction View in ventricular onset (VIVO) is a non-invasive mapping system used for localising the site of earliest activation in ventricular arrhythmia, utilising a mathematical algorithm, patient specific cardiac model (constructed using cross-sectional imaging data), 3D images of the patient’s torso (for localising surface electrodes), and a 12-lead electrocardiogram (ECG).(1, 2) Several publications have examined its role in the localisation of premature ventricular contractions (PVCs), and a 5 patient case series assessed its role in scar related re-entrant VT.(1-4) However, its validity in a larger cohort and of the relationship to the relevant myocardial scar has not been investigated. Objective Assess the accuracy of the VIVO mapping system in localising the VT-SoO for patients with scar related re-entrant VT and its relationship to the relevant myocardial scar on cross-sectional imaging. Methods 20 patients with structural heart disease (18 ischaemic cardiomyopathy (ICM), 1 dilated cardiomyopathy (DCM), 1 hypertrophic cardiomyopathy (HCM)) (Male n=18, 63±14 years) and recent cross-sectional cardiac imaging, were recruited over a 16-month period (table 1). All patients had a clinical indication for VT ablation and were on optimal medical therapy, 19 had an implantable cardiac defibrillator. Invasive electro-anatomical mapping (EAM) was performed with the Advisor HD Grid multipolar catheter and maps were generated using Omnipolar electrograms (EGMs). The VT-SoO was identified using an activation- or pace-map by an experienced operator and the location defined using the American heart association’s 17 segment model of the left ventricle during the procedure.(5) VIVO maps were reviewed by a second independent operator and a segment allocated, scar segments were obtained from cross-sectional imaging. A "complete match" was defined as exact segment concordance between allocated segments, "partial match" as adjacent segments, and "no match" if it does not satisfy either of those requirements. Results Mean left ventricular ejection fraction was 35.5 ± 10.6%. Mean procedure time was 242 ± 70 minutes, with a mean ablation time of 20 ± 11.1 minutes. A total of 32 re-entrant VTs were mapped. The VT exit site was identified in all cases (11 activation-map; 21 pace-map). A complete match between the EAM and VIVO map was seen in 75% of VTs and partial match in a further 15% (table 2). The VT-SoO was located withing the myocardial scar (or directly adjacent to is) in 83% of accurately mapped VTs. Procedural success (defined as freedom from device treated episodes) was seen in 90% of patients at mean follow up of 7.3 ± 4.7 months. Conclusion VIVO non-invasive mapping system was able to accurately map the VT-SoO in scar dependent VT, and identify the relevant myocardial scar as seen on cross sectional imaging. Further research assessing its ability to accurately identify relevant ablation targets is ongoing.

Collision mapping enables accurate localization of the slow pathway in atrioventricular nodal reentrant tachycardia

Abstract Introduction Atrioventricular Node Reentry Tachycardia (AVNRT) is commonly treated with catheter ablation, with high success and low complication rates. However a small risk of complete AV block still remains. Recent studies could show that using collision map is a feasible approach in mapping the slow pathway. The aim of the current study is to show a reduction of the total ablation points needed to modify/ablate the slow pathway using the collision mapping compared to conventional 3D mapping guided slow pathway modulation/ablation and therefore minimize the risk of a complete heart block. Methods Patients diagnosed with AVNRT (n = 24) underwent collision mapping for slow pathway identification, compared to a historical cohort (n=76) using conventional mapping. For collision mapping a dynamic visualization of atrial propagation during sinus rhythm was condcted. Two propagation fronts were observed to collide at the triangle of Koch, one propagation through the slow and one through the fast pathway. The designated collision zone was considered ideal for catheter ablation (Figure 1). The endpoint after ablation in both groups was non-inducibility of AVNRTs. Results After propensity score matching the collision mapping group needed significantly fewer ablation impulses (2 (IQR 1 - 5) vs. 6 (IQR 2,5 - 11,5) p = 0.002) and shorter ablation time (p < 0.001) compared to the conventional group (Table 1). No significant differences were observed in procedure time (p = 0.209), fluoroscopy time (p = 0.296), or dose area product (p = 0.391). Conclusion Collision Mapping in AVNRT ablation showed a notable reduction in ablation points, suggesting enhanced procedural efficiency and safety.Figure 1Table1

Early ablation leads to better outcome in patients < 55 years with persistent atrial fibrillation

The question of optimal timing for catheter ablation of atrial fibrillation (AF) to achieve best outcomes remains a crucial clinical issue. As AF occurs less frequently in younger patients, data regarding Diagnosis-to-Ablation Time (DAT) is especially limited in patients under the age of 55 years with persistent AF. We therefore analyzed the temporal relationship between initial AF presentation and timing of catheter ablation in this cohort. We conducted a retrospective single-centre study of patients ≤ 55 years with persistent AF who underwent first-time catheter ablation at our center. The cohort was divided into patients that underwent catheter ablation after diagnosis of persistent AF within a DAT of ≤ 12 months and patients with a DAT of > 12 months. A total of 101 patients (median age 51 years; female n = 19 (18.8%)) with persistent AF were included. Ablation was performed within 12 months (“early DAT”) in 51 patients and > 12 months (“late DAT”) in 50 patients. Pulmonary vein isolation was performed using high-power short-duration (HPSD) radiofrequency ablation. Median DAT was 5 months (1–12 months) in the early ablation group and 36 months (13–240 months) in the late ablation group. The median follow-up was 11.3 months (0.03–37.1 months). The rate of any atrial arrhythmia recurrence after a 30-day blanking period was significantly lower in the early DAT group (13/51 patients; 25.5%) as compared to the late DAT group (26/50 patients; 52.0%) (log rank test; p = 0.003). Catheter ablation performed > 12 months after the initial AF diagnosis was an independent predictor for the occurrence of any atrial arrythmia (OR: 2.58; (95%-CI: 1.32–5.07). Early first-time catheter ablation (DAT ≤ 12 months) in patients ≤ 55 years with persistent AF is associated with a significantly lower rate of arrhythmia recurrence.

Comparing Low-to-Zero Fluoroscopic Navigation Systems for AVNRT Catheter Ablation: A Network Meta-Analysis.

Low-to-zero fluoroscopic navigation systems lower radiation exposure which improves health outcomes. Conventional x-ray fluoroscopy (CF) has long been the standard to guide to catheter location for cardiac ablation. With advancements in technology, alternative safety navigation systems have been developed. Three primary modalities commonly utilized are three-dimensional electroanatomic mapping (3D-EAM), magnetic navigation system (MNS), and intracardiac echocardiography (ICE), all of which can reduce radiation exposure during the procedure. We aim to compare the efficacy and safety among ICE, EAM, MNS, and CF in ablation of atrioventricular nodal reentrant tachycardia (AVNRT). This is a meta-analysis consisting of observational studies and randomized controlled trials, which evaluated the performance of navigation systems of catheter ablation in AVNRT patients. Primary endpoint was to access the AVNRT recurrence after the procedure during follow-up periods. Secondary endpoints were technical success, fluoroscopic time, fluoroscopic dose area product, radiofrequency ablation time, and adverse events. Random-effect model was applied for pooled estimated effects of included studies. A total of 21 studies (21 CF, 2 ICE, 9 EAM, 11 MNS) including 1716 patients who underwent catheter ablation for AVNRT treatment were analyzed. Of these, 16 were observational studies and 5 were randomized controlled trials. Point estimation of AVNRT recurrence showed ICE exhibited a pooled odds ratio (ORs) of 1.06 (95% confidence interval [CI]: 0.064-17.322), MNS with ORs of 0.51 (95% CI: 0.214-1.219], and EAM with ORs of 0.394 (95% CI: 0.119-1.305) when compared to CF. EAM had significant higher technical success with ORs of 2.781 (95% CI: 1.317-5.872) when compared to CF. Regarding fluoroscopy time, EAM showed the lowest time with mean differences (MD) of -10.348 min (95% CI: -13.385 to -7.3101) and P-score of 0.998. It was followed by MNS with MD of -3.712 min (95% CI: -7.128 to -0.295) and P-score of 0.586, ICE with MD of -1.150 min (95% CI: -6.963 to 4.662) with a P-score of 0.294 compared to CF, which has a P-score of 0.122. There were insignificant adverse events across the procedures. AVNRT ablation navigated by low-to-zero fluoroscopic navigation systems achieves higher efficacy and comparable safety to conventional fluoroscopywhile also reducing risk of radiation exposure time.

Microwave Ablation after VATS in Patients with Multiple Pulmonary Nodules.

The management of residual nodules after video-assisted thoracoscopic surgery (VATS) for multiple pulmonary nodules (MPNs) is challenging. Microwave ablation (MWA), which is highly repeatable and minimally invasive, has garnered widespread attention in the treatment of MPNs. Ninety-one patients with MPNs who underwent VATS for resection of high-risk nodules followed by MWA for residual nodules were examined. Clinical efficacy and complications were assessed. The primary end points were MWA success rate and complete ablation rate. Secondary end points were local progression-free survival (LPFS), overall survival (OS), and complications. MWA was successfully completed in all patients. Mean tumor diameter, ablation time, and ablation output power were 0.81 cm, 3.4 minutes, and 39 W, respectively. LPFS was 100% at 3, 6, 12, and 24 months, respectively. OS was 100% at 12 and 24 months, respectively. No intraoperative or postoperative deaths occurred. Complications with MWA were infrequent. Pneumothorax was most common, occurring in 31 patients (34.07%); among these, seven (7.69%) required closed thoracic drainage. Pleural effusion occurred in six patients (6.59%), hydropneumothorax in five (5.49%), and pneumonia in three (3.30%). The pain level after MWA was moderate-to-severe in 29 patients (31.87%). MWA is safe and feasible for treating residual nodules in patients with MPNs who have undergone VATS. The incidence of complications was low, and most complications were mild.

Invasive management of atrial tachycardias using a novel lattice-tip catheter combining high-density mapping and dual ablation properties: initial real-world experience.

Invasive management of atrial tachycardias(ATs) requires proper diagnosis of the mechanism followed by elimination of the responsible substrate. A novel lattice-tip catheter with both high-density mapping and dual ablation properties(radiofrequency-RF/pulsed field ablation-PFA) has been recently introduced for catheter ablation of atrial fibrillation. We present the first study to assess its performance in the management of ATs (diagnostic and therapeutic). Patients with documented ATs were selected. Activation mapping was used for the establishment of the AT mechanism. Confirmation with entrainment was performed, whenever appropriate. Accuracy of the activation mapping in diagnosis, acute ablation efficacy, and procedural characteristics were the study endpoints. Twenty patients were included (12 cavotricuspid isthmus-dependent atrial flutters, 5 mitral flutters, 2 roof flutters, and 2 focal ATs). Proper diagnosis was established by activation mapping in all cases. The mean mapping time was 7.85 ± 3.06 min with 296.82 ± 150.9 mean mapping points/minute. The mean ablation time was 54.25 ± 42.97 s. Conversion to sinus rhythm during ablation was achieved in all cases with the exception of a roof flutter that converted to mitral flutter and a case of a parahisian AT in which ablation was not attempted. Patients that received ablation did not experience any arrhythmia recurrence in a mean follow up of 4.14 ± 0.91months. No major or minor complications occurred. The lattice-tip catheter and its dedicated electroanatomical mapping system provided sufficiently detailed activation mapping for the diagnosis of the AT mechanism. The delivered lesions were highly effective acutely, with no adverse events. However, limitations exist and should be acknowledged.

Lesion characteristics using high-frequency low-tidal volume ventilation versus standard ventilation during ablation of paroxysmal atrial fibrillation.

High-frequency low-tidal-volume (HFLTV) ventilation during radiofrequency catheter ablation (RFCA) for paroxysmal atrial fibrillation (PAF) has been shown to be superior to standard ventilation (SV) in terms of procedural efficiency, acute and long-term clinical outcomes. Our study aimed to compare ablation lesions characteristics utilizing HFLTV ventilation versus SV during RFCA of PAF. A retrospective analysis was conducted on patients who underwent pulmonary vein isolation (PVI) for PAF between August 2022 and March 2023, using high-power short-duration ablation. Thirty-five patients underwent RFCA with HFLTV ventilation and were matched with another cohort of 35 patients who underwent RFCA with SV. Parameters including ablation duration, contact force (CF), impedance drop, and ablation index were extracted from the CARTONET database for each ablation lesion. A total of 70 patients were included (HFLTV = 35/2484 lesions, SV = 35/2830 lesions) in the analysis. There were no differences in baseline characteristics between the groups. While targeting the same ablation index, the HFLTV ventilation group demonstrated shorter average ablation duration per lesion (12.3 ± 5.0 vs. 15.4 ± 8.4 s, p < .001), higher average CF (17.0 ± 8.5 vs. 10.5 ± 4.6 g, p < .001), and greater impedance reduction (9.5 ± 4.6 vs. 7.7 ± 4.1 ohms, p < .001). HFLTV ventilation group also demonstrated shorter total procedural time (61.3 ± 25.5 vs. 90.8 ± 22.8 min, p < .001), ablation time (40.5 ± 18.6 vs. 65.8 ± 22.5 min, p < .001), and RF time (15.3 ± 4.8 vs. 22.9 ± 9.7 min, p < .001). HFLTV ventilation during PVI for PAF was associated with improved ablation lesion parameters and procedural efficiency compared to SV.

Shear Wave Elastography in Evaluating the Efficacy of Liver Microwave Ablation: An Experimental Study

Background: The effect of microwave ablation on small hepatocellular carcinoma is not significantly different from that of surgical resection. Accurate assessment of the ablation effect is crucial for ensuring the safety and effectiveness of hyperthermia. Objectives: This study aimed to explore the feasibility and accuracy of supersonic shear wave elastography (SWE) in quantitatively evaluating the microwave ablation margin of the liver. Materials and Methods: Three surgeons were each randomly assigned 4 Wuzhishan miniature pigs (WZSPs) to perform 12 ablation procedures at an ablation power of 40 W. Based on the ablation time, the lesions were divided into 15, 30, and 60-second groups. Immediately after ablation, SWE and modulus measurements were performed 5 times for each ablation lesion. The SWE data were expressed as mean ± standard deviation. Within-group and between-group comparisons were made using repeated measures analysis of variance. Results: A total of 144 effective ablations and 131 effective pathological results were obtained. Within the same ablation time, the elastic modulus increased in the surrounding normal tissue, ablation margin, and ablation center regions in a stepwise manner (P &lt; 0.01). However, in the ablation center region, the elastic modulus decreased in a stepwise manner with the shortening of ablation time [60 s (97.16 ± 14.58 kPa) &gt; 30 s (77.84 ± 9.64 kPa) &gt; 15 s (38.92 ± 3.12 kPa)], with statistically significant differences (F = 2,131.832, P &lt; 0.01). The elastic modulus of the ablation margin region at different ablation times remained between 22.68 - 23.56 kPa. Conclusion: The elastic modulus range in the ablation margin region after microwave ablation is relatively fixed. Shear wave elastography aids in the quantitative evaluation of the ablation margin region of the liver and has high practical value in monitoring and evaluating ultrasound ablation.

Deriving seasonal and annual surface mass balance for debris-covered glaciers from flow-corrected satellite stereo DEM time series

Abstract Glaciers in High-Mountain Asia are experiencing varying rates and patterns of mass loss due to a complex interplay between glacier surface processes, local conditions and climate forcing. Spatially distributed surface mass balance (SMB) estimates can provide valuable insight into these drivers, but observations are currently limited in both space and time. We used very-high-resolution optical stereo images acquired by commercial satellites to prepare time series of digital elevation models (DEMs), and derived contemporaneous surface velocity and elevation change products for six debris-covered glaciers in Nepal. We developed new methods to produce flow-corrected Lagrangian SMB maps to isolate local surface ablation signals with enough detail to study individual ice cliffs. Our results show reduced ablation under thick debris cover and enhanced ablation over ice cliffs. Ablating ice cliffs were responsible for $10\!-\!38\%$ of the total ablation over debris-covered areas, even though they covered $\leq \!11\%$ of the total area. Seasonal SMB products reveal the timing and patterns of summer accumulation and ablation, underscoring the importance of snow avalanches for low-elevation debris-covered glaciers in the region. Our approach can be applied to other glaciers with repeat high-resolution DEM coverage and extended for regional analyses of SMB on seasonal to interannual timescales.

Scatterer spacing based on Gabor atoms matched from harmonic ultrasound echoes to improve assessment of microwave‐induced thermal lesions

AbstractBackgroundMicrowave ablation (MWA) is a minimally invasive alternative for the treatment of unresectable liver tumors. To verify the effectiveness and safety of MWA, it is critical to measure the temperature variation and assess the regions of the microwave‐induced thermal lesions.PurposeRecent studies have indicated that the locations of optimally matched Gabor atoms (LOMGA) from ultrasound radiofrequency (RF) echo signals allow accurate and stable scatterer spacing estimation. Herein, a harmonic‐based LOMGA method is proposed to estimate the scatterer spacing for improving the assessment of microwave‐induced thermal lesions.MethodsThe mean scatterer spacing (MSS) is estimated via the LOMGA method incorporating the selection of concise atoms from separated second‐harmonic RF echo signals with the pulse‐inversion algorithm for thermal lesion evaluation. In vitro experiments, 10 fresh porcine liver samples were ablated at different time nodes during the ablation period, and 200 sets of second‐harmonic and fundamental RF echo signals were randomly selected from the regions of interest in the coagulated liver samples for MSS estimation. The means and standard deviations of the MSSs, as well as the linear regression for the mean MSSs, were calculated from fundamental and second‐harmonic signals for comparison and evaluation, the receiver operating characteristic (ROC) curves for the 200 sets of fundamental‐based and harmonic‐based MSS estimates from the 10 liver samples at five pairs of adjacent time nodes were calculated, and one‐way analysis of variance (ANOVA) tests were performed for the five pairs of adjacent time nodes. The fundamental and harmonic‐based p‐values in the ANOVA tests and the areas under the ROC curves (AUCs) were calculated to statistically analyze the differences in the MSSs between adjacent time nodes.ResultsThe harmonic‐based increments in the intensity variation and coherent components were larger than the fundamental‐based increments with the increasing ablation time. The harmonic‐based MSSs from the 10 liver samples at five pairs of adjacent time nodes were found to be highly statistically significant (p &lt; 0.01). Thus, the harmonic‐based MSSs had greater variations. Compared with the fundamental‐based results, for the five preset ST values, the average increment in the harmonic‐based mean slopes was 69.22% and the average decrement in the mean standard deviations was 11.67% for the linear‐fitting MSS results, and the results were statistically significant (p &lt; 0.05).ConclusionHarmonic‐based MSSs are more sensitive and robust to variations in coagulated tissues, which is advantageous for the assessment of microwave‐induced thermal lesions.

The effect of different power radiofrequency ablations in treatment and postoperative pain in patients with atrial fibrillation: a retrospective study

BackgroundThere has been no consensus on what power of radiofrequency energy can be used to produce the best surgical results in patients with atrial fibrillation. In addition, patients undergoing local anesthesia and fentanyl analgesia may experience pain when radiofrequency ablation is performed. This study investigated the effect of different power radiofrequency ablations in treatment and postoperative pain in patients with atrial fibrillation.MethodsA retrospective study was performed with 60 patients who underwent radiofrequency ablation for atrial fibrillation between January and June 2023. Patients were divided into 2 groups according to the power of the radiofrequency ablation catheter used, with 30 patients in the conventional power group (35 W) and 30 patients in the high-power group (50 W). The cardiac electrophysiological indexes and postoperative pain of the 2 groups were compared.ResultsMost of the procedural key parameters between the 2 groups had no significant differences. However, the total application time during radiofrequency ablation and pulmonary vein isolation time in the high-power group were significantly shorter than those in the conventional power group (p < 0.001). Patients in the high-power group reported significantly less pain than those in the conventional power group in the immediate postoperative period and the late postoperative period (p < 0.001).ConclusionsHigh-power radiofrequency ablation showed a shorter treatment time, and could reduce postoperative pain compared to conventional power ablation.

Electrophysiological Cardiovascular Magnetic Resonance (EP-CMR)-Guided Interventional Procedures: Challenges and Opportunities.

Cardiovascular magnetic resonance (CMR) imaging excels in providing detailed three-dimensional anatomical information together with excellent soft tissue contrast and has already become a valuable tool for diagnostic evaluation, electrophysiological procedure (EP) planning, and therapeutical stratification of atrial or ventricular rhythm disorders. CMR-based identification of ablation targets may significantly impact existing concepts of interventional electrophysiology. In order to exploit the inherent advantages of CMR imaging to the fullest, CMR-guided ablation procedures (EP-CMR) are justly considered the ultimate goal. Electrophysiological cardiovascular magnetic resonance (EP-CMR) interventional procedures have more recently been introduced to the CMR armamentarium: in a single-center series of 30 patients, an EP-CMR guided ablation success of 93% has been reported, which is comparable to conventional ablation outcomes for typical atrial flutter and procedure and ablation time were also reported to be comparable. However, moving on from already established workflows for the ablation of typical atrial flutter in the interventional CMR environment to treatment of more complex ventricular arrhythmias calls for technical advances regarding development of catheters, sheaths and CMR-compatible defibrillator equipment. CMR imaging has already become an important diagnostic tool in the standard clinical assessment of cardiac arrhythmias. Previous studies have demonstrated the feasibility and safety of performing electrophysiological interventional procedures within the CMR environment and fully CMR-guided ablation of typical atrial flutter can be implemented as a routine procedure in experienced centers. Building upon established workflows, the market release of new, CMR-compatible interventional devices may finally enable targeting ventricular arrhythmias.

Efficacy of balloon-expandable extreme-low-temperature ventricular epicardial cryoablation: A preclinical proof of concept evaluation

BackgroundCurrent epicardial ablation technologies are limited by the inability to create adequate depth lesions and risk of collateral injury to extracardiac structures. ObjectiveThe purpose of this study was to evaluate the feasibility and efficacy of ventricular epicardial ablation with a novel balloon-expandable extreme-low-temperature (XLT) cryoablation catheter with an embedded insulation pontoon for protection of extracardiac structures, which has been specifically designed for epicardial ablation. MethodsTen healthy swine underwent surgical (n = 6) and subxiphoid percutaneous (n = 4) epicardial access. A total of 3–6 sites were targeted in the right and left ventricular wall for different exposure durations. Ablation was performed with a large footprint (surgical) and smaller footprint (percutaneous) version of the HeartPad (Corfigo Inc., Montclair, NJ) XLT system. The system consists of the balloon-expandable cryoablation catheter and a console. The console vaporizes liquid helium (–269°C) and controls continuous delivery of extremely cold helium gas at high flow rates through a high-efficiency ablation element mounted on an expandable insulation pontoon to protect extracardiac structures. Ablation lesions were assessed by gross pathology and histologic examination. ResultsA total of 42 epicardial lesions were created. Mean lesion depth increased progressively with ablation time (surgical catheter: 11 ± 2 mm at ≤30 seconds, 13 ± 4 mm at 60 seconds, 15 ± 3 mm at ≥120 seconds, P = .001; percutaneous catheter: 10 ± 2 mm at 30 seconds, 14 ± 2 mm at 60 seconds, 16 ± 2 mm at 120 seconds, P = .001). Lesion geometry seemed unaffected by presence and thickness of epicardial fat. One episode of ventricular fibrillation occurred after ablation over the atrioventricular groove and 2 adjacent obtuse marginal arteries. ConclusionSurgical or percutaneous epicardial ablation using the HeartPad XLT cryoablation system is feasible and can efficiently produce deep ventricular lesions in different epicardial locations.

Early Cryoablation After First Diagnosis of Atrial Fibrillation Reduces Arrhythmia Recurrence in Heart Failure Patients

BackgroundAtrial fibrillation (AF) and heart failure (HF) often coexist, leading to increased mortality. A cryoballoon-based approach is a potential treatment for patients with HF because of its safety and efficacy. ObjectivesThe authors sought to evaluate the optimal timing of cryoballoon ablation after the first clinical diagnosis of AF and its prognosis for patients with HF. MethodsThis large-scale multicenter study retrospectively collected data of patients with HF who underwent cryoballoon ablation for AF from 17 Japanese institutions. Patients were divided into 2 groups depending on the duration between the first diagnosis and ablation using a median time of 0.5 year (IQR: 0.3-2.0 years). Clinical endpoints of recurrence, mortality, and HF hospitalization were compared between the 2 groups. ResultsAmong 3,655 patients, 543 with HF were included for analysis. During a median follow-up period of 21.3 months (IQR: 12.0-36.8 months), 151 of 520 patients (29%) had a recurrence. The AF recurrence rate was significantly lower in the early-ablation group (≤0.5 year) than in the delayed-ablation group (>0.5 year) (24% [65/266] vs 34% [86/254], respectively; P = 0.018). In the multivariable analysis, early ablation ≤ 0.5 year was independently associated with an absence of recurrence (HR: 0.581; 95% CI: 0.401-0.842; P = 0.004). Delayed time for cryoballoon ablation incrementally increased the risk of postablation recurrence. Antiarrhythmic drug use was independently associated with delayed ablation. No significant differences in mortality or HF hospitalization were observed between the 2 groups. ConclusionsEarly cryoablation reduced the risk of recurrence in patients with HF, which may help improve clinical management.

Prognostic impact of diagnosis-to-ablation time on outcomes following catheter ablation in persistent atrial fibrillation and left ventricular systolic dysfunction

BackgroundThe optimal timing of catheter ablation in individuals with atrial fibrillation (AF) and left ventricular systolic dysfunction (LVSD) remains uncertain. ObjectiveWe examined whether AF diagnosis to ablation time (DAT) influences outcomes following catheter ablation (CA) in patients with persistent AF (PsAF) and LVSD from the CAMERA-MRI and CAPLA randomized studies. MethodsWe evaluated clinical outcomes according to DAT < 1 year (“shorter DAT”) and ≥1 year (“longer DAT”), comparing AF recurrence, AF burden, left ventricular ejection fraction (LVEF), and LV recovery (LVEF ≥ 50%) at 12 months. DAT was also compared according to the median (24 months). ResultsTwo hundred and ten individuals with AF and LVSD were identified, with a median DAT of 24 months. Shorter DAT was associated with lower LA global and posterior wall scar (<0.05 mV; both P < .05). At 12 months, 69.4% with shorter DAT (<1year) were free from recurrent atrial arrhythmias vs 53.6% in longer DAT (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.01–2.65, P = .040). Median AF burden was 0% in both groups (shorter DAT: interquartile range [IQR] 0.0–2.0% vs longer DAT: IQR 0.0–7.3%, P = .017). At 12 months, shorter DAT was associated with higher LVEF (55.3% vs 51.0%, P = .009), greater LVEF improvement (+20.8 ± 13.0% vs +13.9 ± 13.2% longer DAT, P < .001) and LV recovery (75.0% vs longer DAT: 57.2%, P = .011). Shorter DAT was associated with fewer hospitalizations and electrical cardioversions at 12 months. ConclusionIn individuals with AF and LVSD, shorter DAT was associated with greater LVEF improvement and arrhythmia-free survival with lower AF burden and rehospitalization at 12 months, highlighting the prognostic benefit of early CA in AF and LVSD.

789. EFFICACY AND SAFETY OF CRYOBALLOON-180 ABLATION FOR THE TREATMENT OF DYSPLASTIC BARRETT ESOPHAGUS: PRELIMINARY RESULTS FROM A PROSPECTIVE MULTICENTER STUDY

Abstract Background Cryoballoon-ablation is a relatively novel method for the eradication of dysplastic Barrett esophagus (BE). While the focal cryoballoon-ablation system has shown to be efficacious for BE of limited extent, the cryoballoon180-ablation system (CBAS180) is developed to treat longer BE segments by semi-circumferential ablation over 3cm, in a single step. A first-in-human study demonstrated the feasibility of CBAS180 treatment, yet the optimal dose needs to be determined. The current prospective, multicenter study, investigates CBAS180 at lower dosages for patients with dysplastic BE. Methods A total of 62 patients with ablation naïve BE (C≤3 and M≥1) will be enrolled in six Dutch Barrett expert centers. Treatment consists of a full circumferential ablation over 3 cm of length, using two semi-circumferential ablations at a dose of 1.2 mm/sec. Follow-up consisted of phone calls at days 1, 7 and 30, a symptom diary during 14 days, and an endoscopy after 3 months. Outcomes included (1) technical success rate; (2) BE regression percentage at follow-up scored by an independent adjudication committee; (3) incidence of adverse events; (4) post-procedural pain (scored on a scale of 0-10); and (5) post-procedural dysphagia (scored on a validated scale of 0-4). Follow-up treatment consisted of focal cryoballoon-ablation until complete eradication of visible BE was achieved, confirmed by biopsies from the neo-Z-line. Results So far, 25 patients (80% male; mean age 67) with a median BE length of C0M2 (p25-p75 C0-1M2-4) were included. Technical success rate was 92% (23/25; 95% CI 74-99%). In two patients, treatment was technically unsuccessful due to unstable positioning of the balloon (n=1) or a device malfunction (n=1). Median procedure time was 14 (p25-p75 11-16) 4) minutes and median ablation time was 5 (p25-p75 3-5) minutes. All 23 successfully treated patients completed follow-up endoscopy at 3 months. Median BE regression was 90% (p25-p75 75%-100%) evaluated by the independent adjudication committee. Overall, CBAS180 adverse event rate was 8% (2/23); one patient developed esophageal stricture (1/23; 4% [95% CI 1-16%]) resolved after a single endoscopic dilation. Another patient (1/23; 4% [95% CI 1-16%]) experienced post-procedural bleeding, with re-endoscopy without intervention. The CBAS180 procedure was well tolerated with low post-procedural pain (median 2 [p25-p75 1-4] at day 1 and 0 [p25-p75 0-1] at day 7) and dysphagia (56% and 70% of patients with score 0 at days 1 and 7, respectively) scores. So far, 22/23 (95%) patients were additionally treated with focal cryoballoon-ablation and 18/22 (82%) achieved a complete endoscopis and histologic eradication of BE after median 1 (p25-p75 1-3) treatment, the other 4 are still under treatment. After focal cryoballoon-ablation, 2/22 patients developed strictures, resolved after 1 and 2 endoscopic dilatations. Conclusion Based on these preliminary results, circumferential ablation with CBAS180 at 1.2 mm/sec, followed by focal cryoballoon-ablation, emerges as an effective and safe procedure for dysplastic BE eradication in the hands of expert endoscopists. Further avenues for exploration should encompass the assessment of multiple CBAS180 ablations stacked on top of each other in larger segments and the validation of outcomes in a larger patient cohort.