Novel Radiofrequency Balloon Catheter　- Impact of Ablation Parameters on Single-Shot Isolation.

BACKGROUND: A novel multielectrode radiofrequency balloon (RFB) catheter has been released for pulmonary vein isolation (PVI).Methods and Results: In this observational study consecutive patients with drug-refractory paroxysmal or persistent atrial fibrillation (AF) undergoing first-time PVI were enrolled in 2 high-volume ablation centers. All procedures were conducted in conjunction with a 3D-mapping system. Clinical, procedural and ablation parameters were systematically analyzed. 105 patients (58% male; 52% paroxysmal AF, 68±11.3 years mean age, left atrial volume index 38.6±14.8 mL/m2) were included. 241/412 (58.5%) PVs were successfully isolated with a single shot (SS), with a time-to-isolation of 11.6±8 s. Total number of radiofrequency applications was 892 (mean 2.2/PV), resulting in successful isolation of 408/412 (99%) PVs at the end of the procedure. Mean electrodes' impedance drop was significantly higher in the SS-PVI compared with non-SS applications (21.5±6.6 vs. 18.6±6.5 Ohm). Concordantly, higher temperature rise was observed in the SS vs. non-SS applications (10.9±4.9℃ vs. 9.6±4.7℃). CONCLUSIONS: In this multicenter real-world study, mean impedance drop and temperature rise were associated with successful SS-PVI applying the novel RFB catheter. These parameters may help to guide efficient usage of the new RF balloon.

Electrographic flow-guided ablation in redo patients with persistent atrial fibrillation (FLOW-AF): design and rationale.

Background: Electrographic flow (EGF) mapping enables the dynamic detection of functional or active atrial fibrillation (AF) sources outside the pulmonary veins (PVs), and the presence or absence of these sources offers a novel framework for classifying and treating persistent AF patients based on the underlying pathophysiology of their AF disease. Objective: The primary objective of the FLOW-AF trial is to evaluate the reliability of the EGF algorithm technology (Ablamap software) to identify AF sources and guide ablation therapy in patients with persistent AF. Methods: The FLOW-AF trial (NCT04473963) is a prospective, multicenter, randomized clinical study in which patients with persistent or long-standing persistent AF who have failed prior PV isolation (PVI) undergo EGF mapping after confirmation of intact PVI. In total, 85 patients will be enrolled and stratified based on the presence or absence of EGF-identified sources. Patients with an EGF-identified source above the predetermined activity threshold of ≥26.5% will be randomized in a 1:1 fashion to PVI only vs PVI + ablation of EGF-identified extra-PV sources of AF. Results: The primary safety endpoint is freedom from serious adverse events related to the procedure through 7 days following the randomization procedure; and the primary effectiveness endpoint is the successful elimination of significant sources of excitation with the target parameter the activity of the leading source. Conclusions: The FLOW-AF trial is a randomized study designed to evaluate the ability of the EGF mapping algorithm to identify patients with active extra-PV AF sources.

Management of pericardial tamponade in the electrophysiology laboratory: results from a national survey.

BACKGROUND: Despite continued efforts to improve the safety of catheter ablation, pericardial tamponade remains one of its more frequent, potentially life-threatening complications. Management of cardiac tamponade is not standardized and uncertainties regarding acute treatment remain. METHODS: This survey sought to evaluate the management of cardiac tamponade in German EP centers via a standardized postal questionnaire. All 341 identified German EP centers were invited to return a questionnaire on their standards for the management of cardiac tamponade. RESULTS: A total of 189 German EP centers completed the questionnaire. Several precautions are followed to avoid pericardial tamponade: A minority of centers preclude very old patients (19%) or those with a high body mass index (30%) from ablation. Non-vitamin K antagonist oral anticoagulants are briefly paused in most centers (88%) before procedures, while vitamin K antagonists are continued. Pericardial tamponade is usually treated using reversal of heparin by applying protamine (86%) and pericardiocentesis under both, fluoroscopic and echocardiographic guidance (62%). A pigtail catheter is mostly inserted (97%) and autotransfusion of aspirated blood is performed in 47% of centers. The decision for surgical repair depends on different clinical and infrastructural aspects. The timing of reinitiation of anticoagulation widely differs between the centers. Approximately 1/3 of centers prescribe nonsteroidal anti-inflammatory agents, colchicine or steroids after pericardiocentesis. CONCLUSION: The present survey shows that the management of cardiac tamponade is still inhomogeneous in German ablation centers. However, multiple findings of this survey can be generalized and might guide especially less experienced operators and centers in their treatment and decision strategies.

Pulsed-field ablation-based pulmonary vein isolation: acute safety, efficacy and short-term follow-up in a multi-center real world scenario.

PURPOSE: Pulsed-field ablation (PFA) is a new energy source to achieve pulmonary vein isolation (PVI) by targeted electroporation of cardiomyocytes. Experimental and controlled clinical trial data suggest good efficacy of PFA-based PVI. We aimed to assess efficacy, safety and follow-up of PFA-based PVI in an early adopter routine care setting. METHODS: Consecutive patients with symptomatic paroxysmal or persistent atrial fibrillation (AF) underwent PVI using the Farawave® PFA ablation catheter in conjunction with three-dimensional mapping at two German high-volume ablation centers. PVI was achieved by applying 8 PFA applications in each PV. RESULTS: A total of 138 patients undergoing a first PVI (67 ± 12 years, 66% male, 62% persistent AF) were treated. PVI was achieved in all patients by deploying 4563 applications in 546 PVs (8.4 ± 1.0/PV). Disappearance of PV signals after the first application was demonstrated in 544/546 PVs (99.6%). More than eight PFA applications were performed in 29/546 PVs (6%) following adapted catheter positioning or due to reconnection as assessed during remapping. Mean procedure time was 78 ± 22 min including pre- and post PVI high-density voltage mapping. PFA catheter LA dwell-time was 23 ± 9 min. Total fluoroscopy time and dose area product were 16 ± 7 min and 505 [275;747] cGy*cm2. One pericardial tamponade (0.7%), one transient ST-elevation (0.7%) and three groin complications (2.2%) occurred. 1-year follow-up showed freedom of arrhythmia in 90% in patients with paroxysmal AF (n = 47) and 60% in patients with persistent AF (n = 82, p = 0.015). CONCLUSIONS: PFA-based PVI is acutely highly effective and associated with a beneficial safety and low recurrence rate.

Revival of the Forgotten.

Pulmonary vein (PV) isolation (PVI) by continuous, transmural and durable lesions is decisive for ensuring long-term freedom from atrial fibrillation (AF). AF ablation requires irrigated tip catheters to reduce thromboembolic complications. This precluded temperature-controlled delivery of radiofrequency (RF) energy.The aim of this study was to evaluate feasibility, acute efficacy, and safety of an irrigated, temperature-controlled ablation catheter [DiamondTemp™ (DT) Medtronic®] for PVI.Consecutive patients with AF underwent PVI using the DT catheter combined with high-power short-duration RF applications. Ablation settings were (1) a catheter tip temperature limit of 60°C, (2) a temperature-controlled power of 50 W, and (3) application duration of 10 seconds. The primary endpoint was acute isolation of PVs, reassessed after a 30-minute waiting period. Secondary endpoints included procedural parameters (defined as a catheter tip temperature of 50°C > 3 seconds, an impedance drop of 5-10 Ω) and the occurrence of serious adverse events.Fifty consecutive patients [mean age 66 ± 12 years, 38 (76%) women, 24 patients with paroxysmal AF (48%)] were included. Median procedure and left atrial dwell time was 89 [68; 107] and 63 [52; 79] minutes, respectively. Mean number of RF applications was 59 ± 20, and mean total RF duration was 14 ± 6 minutes. Acute PVI was achieved in all patients solely using DT ablation. Acute PV reconnection within the waiting period occurred in five patients; all reconnected PVs were successfully reisolated. One major complication occurred.In this study, the DT ablation system demonstrated high acute efficacy for PVI. Temperature-controlled ablation in conjunction with high-power short-duration applications might be effectively supported.

The impact of ultra-high-density mapping on long-term outcome after catheter ablation of ventricular tachycardia.

Ultra-high-density (UHD) mapping can improve scar area detection and fast activation mapping in patients undergoing catheter ablation of ventricular tachycardia (VT). The aim of the present study was to compare the outcome after VT ablation guided by UHD and conventional point-by-point 3D-mapping. The acute and long-term ablation outcome of 61 consecutive patients with UHD mapping (64-electrode mini-basket catheter) was compared to 61 consecutive patients with conventional point-by-point 3D-mapping using a 3.5 mm tip catheter. Patients, whose ablation was guided by UHD mapping had an improved 24-months outcome in comparison to patients with conventional mapping (cumulative incidence estimate of the combination of recurrence or disease-related death of 52.4% (95% confidence interval (CI) [36.9-65.7]; recurrence: n = 25; disease-related death: n = 4) versus 69.6% (95% CI [55.9-79.8]); recurrence: n = 31; disease-related death n = 11). In a cause-specific Cox proportional hazards model, UHD mapping (hazard ratio (HR) 0.623; 95% CI [0.390-0.995]; P = 0.048) and left ventricular ejection fraction > 30% (HR 0.485; 95% CI [0.290-0.813]; P = 0.006) were independently associated with lower rates of recurrence or disease-related death. Other procedural parameters were similar in both groups. In conclusion, UHD mapping during VT ablation was associated with fewer VT recurrences or disease-related deaths during long-term follow-up in comparison to conventional point-by-point mapping. Complication rates and other procedural parameters were similar in both groups.

Generalizability of the EAST-AFNET 4 Trial: Assessing Outcomes of Early Rhythm-Control Therapy in Patients With Atrial Fibrillation.

Background EAST-AFNET 4 (Early Treatment of Atrial Fibrillation for Stroke Prevention Trial) demonstrated clinical benefit of early rhythm-control therapy (ERC) in patients with new-onset atrial fibrillation (AF) and concomitant cardiovascular conditions compared with current guideline-based practice. This study aimed to evaluate the generalizability of EAST-AFNET 4 in routine practice. Methods and Results Using a US administrative database, we identified 109 739 patients with newly diagnosed AF during the enrollment period of EAST-AFNET 4. Patients were classified as either receiving ERC, using AF ablation or antiarrhythmic drug therapy, within the first year after AF diagnosis (n=27 106) or not receiving ERC (control group, n=82 633). After propensity score overlap weighting, Cox proportional hazards regression was used to compare groups for the primary composite outcome of all-cause mortality, stroke, or hospitalization with the diagnoses heart failure or myocardial infarction. Most patients (79 948 of 109 739; 72.9%) met the inclusion criteria for EAST-AFNET 4. ERC was associated with a reduced risk for the primary composite outcome (hazard ratio [HR], 0.85; 95% CI, 0.75-0.97 [P=0.02]) with largely consistent results between eligible (HR, 0.89; 95% CI, 0.76-1.04 [P=0.14]) or ineligible (HR, 0.77; 95% CI, 0.60-0.98 [P=0.04]) patients for EAST-AFNET 4 trial inclusion. ERC was associated with lower risk of stroke in the overall cohort and in trial-eligible patients. Conclusions This analysis replicates the clinical benefit of ERC seen in EAST-AFNET 4. The results support adoption of ERC as part of the management of recently diagnosed AF in the United States.

The established and the challenger: A direct comparison of current cryoballoon technologies for pulmonary vein isolation.

INTRODUCTION: Cryoballoon (CB) ablation for pulmonary vein isolation (PVI) is an effective treatment of atrial fibrillation (AF). Recently, a novel cryoablation system was introduced. The aim of the study was to compare the safety, efficacy and biophysical characteristics of a novel cryoablation system (POLARx™; Boston Scientific) to a commonly used and clinically well characterized system (Arctic Front Advance Pro™, AFA; Medtronic). METHODS AND RESULTS: Fifty consecutive patients with symptomatic AF, who underwent CB-based ablation with the POLARx were compared to 50 consecutive patients treated with the AFA. Acute PVI was achieved in 99.8% (POLARx 99.5%, AFA 100%, p = 1.00). Time to isolation (TTI) was comparable in both groups (POLARx 35 [27, 48] s, AFA 30 [21, 43] s, p = 0.165). The POLARx showed a lower balloon temperature at TTI (POLARx -44 [-50, -36] °C, AFA -31 [-38, -21] °C, p < 0.001) and lower nadir temperature (POLARx -60 [-65, -55] °C, AFA -48 [-54, -45] °C, p < 0.001). Procedure time (POLARx 80 [60, 105] min, AFA 62 [42, 80] min, p < 0.001), fluoroscopy time (POLARx 17 [13, 22] min, AFA 11 [7, 16] min, p < 0.001) and freeze cycles per patient (POLARx 5 [4, 6], AFA 4.5 [4, 5], p = 0.002) were higher in the POLARx group. Two cerebral ischemic events occurred in the POLARx group, two patients in each group had phrenic nerve injury. CONCLUSION: Both systems enable effective isolation of pulmonary veins. The POLARx required longer procedure and fluoroscopy times. Larger, prospective and randomized studies are needed to assess long-term efficacy and safety of this technology.

Parallel Mapping and Catheter Ablation of Polymorphic Premature Ventricular Contractions: A New Feature for Activation Mapping.

We report the case of an 80-year-old female presenting with polymorphic premature ventricular contractions, nonischemic cardiomyopathy, and severe, secondary mitral regurgitation. Despite a low intraprocedural PVC burden, activation mapping and successful ablation of different morphologies were achieved using a novel mapping tool, which facilitates simultaneous mapping of different PVC morphologies.

High anatomical accuracy of a novel high-resolution wide-band dielectric imaging system in cryoballoon-based ablation.

PURPOSE: Recently, a novel cardiac imaging system based on a wide-band dielectric technology (KODEX-EPD) was introduced to guide catheter ablation. The aim of the study was to evaluate this 3D wide-band dielectric imaging system (WDIS) during cryoballoon (CB)-based atrial fibrillation (AF) ablation focusing on accuracy of pulmonary vein (PV)-anatomy. METHODS: In consecutive patients with symptomatic AF, CB-based ablation was performed in conjunction with the 3D WDIS. Selective PV-angiographies were performed, and 3D anatomy of the left atrium (LA) and PVs using the 3D WDIS was created. The ostial diameters of the ipsilateral right-sided and left-sided PVs and ostial diameters of the right-/left-sided upper/lower PVs demonstrated by selective angiographies were analyzed and compared to 3D WDIS-based PV visualization. RESULTS: In 65 patients (42/65 (65%) male, age 65 ± 9 years, 29/65 (45%) paroxysmal AF) a total of 260 PVs were identified. Median ostial PV-diameters for the ipsilateral left- and right-sided PVs were 38 [34; 43] and 37 [34; 40.3] mm when assessed fluoroscopically and 40 [35.7; 43] and 39 [35.0; 43] mm as demonstrated by 3D WDIS. There was no statistically significant difference between both methods regarding PV-diameter measurements. KODEX-EPD overestimated fluoroscopy measurements by 1.08 mm (95% limits of agreement of -1.93 mm and 4.1 mm). CONCLUSION: The novel wide-band dielectric 3D-imaging system is feasible to create high-resolution images of cardiac structures during CB ablation procedures and accurately visualizes PV-anatomy.

Ablation of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy: Treatment Strategy, Characteristics of Consecutive Atrial Tachycardia and Long-Term Outcome.

Background Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM) and is associated with a deterioration of clinical status. Ablation of symptomatic AF is an established therapy, but in HCM, the characteristics of recurrent atrial arrhythmias and the long-term outcome are uncertain. Methods and Results Sixty-five patients with HCM (aged 64.5±9.9 years, 42 [64.6%] men) underwent AF ablation. The ablation strategy included pulmonary vein isolation in all patients and ablation of complex fractionated atrial electrograms or subsequent atrial tachycardias (AT) if appropriate. Paroxysmal, persistent AF, and a primary AT was present in 13 (20.0%), 51 (78.5%), and 1 (1.5%) patients, respectively. Twenty-five (38.4%) patients developed AT with a total number of 54 ATs. Stable AT was observed in 15 (23.1%) and unstable AT in 10 (15.3%) patients. The mechanism was characterized as a macroreentry in 37 (68.5%), as a localized reentry in 12 (22.2%), a focal mechanism in 1 (1.9%), and not classified in 4 (7.4%) ATs. After 1.9±1.2 ablation procedures and a follow-up of 48.1±32.5 months, freedom of AF/AT recurrences was demonstrated in 60.0% of patients. No recurrences occurred in 84.6% and 52.9% of patients with paroxysmal and persistent AF, respectively (P<0.01). Antiarrhythmic drug therapy was maintained in 24 (36.9%) patients. Conclusions AF ablation in patients with HCM is effective for long-term rhythm control, and especially patients with paroxysmal AF undergoing pulmonary vein isolation have a good clinical outcome. ATs after AF ablation are frequently observed in HCM. Freedom of atrial arrhythmia is achieved by persistent AF ablation in a reasonable number of patients even though the use of antiarrhythmic drug therapy remains high.

Specific electrogram characteristics impact substrate ablation target area in patients with scar-related ventricular tachycardia-insights from automated ultrahigh-density mapping.

INTRODUCTION: Substrate-based catheter ablation approaches to ventricular tachycardia (VT) focus on low-voltage areas and abnormal electrograms. However, specific electrogram characteristics in sinus rhythm are not clearly defined and can be subject to variable interpretation. We analyzed the potential ablation target size using automatic abnormal electrogram detection and studied findings during substrate mapping in the VT isthmus area. METHODS AND RESULTS: Electrogram characteristics in 61 patients undergoing scar-related VT ablation using ultrahigh-density 3D-mapping with a 64-electrode mini-basket catheter were analyzed retrospectively. Forty-four complete substrate maps with a mean number of 10319 ± 889 points were acquired. Fractionated potentials detected by automated annotation and manual review were present in 43 ± 21% of the entire low-voltage area (<1.0 mV), highly fractionated potentials in 7 ± 8%, late potentials in 13 ± 15%, fractionated late potentials in 7 ± 9% and isolated late potentials in 2 ± 4%, respectively. Highly fractionated potentials (>10 ± 1 fractionations) were found in all isthmus areas of identified VT during substrate mapping, while isolated late potentials were distant from the critical isthmus area in 29%. CONCLUSION: The ablation target area varies enormously in size, depending on the definition of abnormal electrograms. Clear linking of abnormal electrograms with critical VT isthmus areas during substrate mapping remains difficult due to a lack of specificity rather than sensitivity. However, highly fractionated, low-voltage electrograms were found to be present in all critical VT isthmus sites.

Outcome after tailored catheter ablation of atrial tachycardia using ultra-high-density mapping.

INTRODUCTION: Tailored catheter ablation of atrial tachycardias (ATs) is increasingly recommended as a potentially easy treatment strategy in the era of high-density mapping (HDM). As follow-up data are sparse, we here report outcomes after HDM-guided ablation of ATs in patients with prior catheter ablation or cardiac surgery. METHODS AND RESULTS: In 250 consecutive patients (age 66.5 ± 0.7 years, 58% male) with ATs (98% prior catheter ablation, 13% prior cardiac surgery) an HDM-guided catheter ablation was performed with the support of a 64-electrode mini-basket catheter. A total of 354 ATs (1.4 ± 0.1 ATs per patient; mean cycle length 304 ± 4.3 ms; 64% macroreentry, 27% localized reentry, and 9% focal) with acute termination of 95% were targeted in the index procedure. A similar AT as in the index procedure recurred in five patients (2%) after a median follow-up time of 535 days (interquartile range (IQR) 25th-75th percentile: 217-841). Tailored ablation of reentry ATs with freedom from any arrhythmia was obtained in 53% after a single procedure and in 73% after 1.4 ± 0.4 ablation procedures (range: 1-4). A total of 228 patients (91%) were free from any arrhythmia recurrence after 210 days (IQR: 152-494) when including optimal usual care. CONCLUSIONS: Tailored catheter ablation of ATs guided by HDM has a high acute success rate. The recurrence rate of the index AT is low. In patients with extensive atrial scaring further ablation procedures need to be considered to achieve freedom from any arrhythmia.

Catheter Ablation of Atrial Fibrillation: State of the Art and Future Perspectives.

PURPOSE OF REVIEW: Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives. RECENT FINDINGS: Catheter ablation is a well-established treatment option for patients with symptomatic AF and is more successful at maintaining SR than antiarrhythmic drugs. Antral pulmonary vein isolation (PVI) as a stand-alone ablation strategy results in beneficial clinical outcomes and is therefore recommended as first-line strategy for both paroxysmal and persistent AF. While radiofrequency-based PVI in conjunction with a three-dimensional mapping system was for many years considered to be the "gold standard", the cryoballoon has emerged as the most commonly used alternative AF ablation tool, especially in patients with paroxysmal AF. Patients with persistent or long-standing persistent AF and with arrhythmia recurrence after previous PVI may benefit from additional ablation strategies, such as substrate modification of various forms or left atrial appendage isolation. New technologies and techniques, such as identification of the AF sources and magnetic resonance imaging-guided substrate modification, are on the way to further improve the success rates of catheter ablation for selected patients and might help to further reduce arrhythmia recurrence. CONCLUSIONS: Pulmonary vein isolation is the treatment of choice for symptomatic patients with paroxysmal and persistent drug-refractory AF. The reconnection of previously isolated pulmonary veins remains the major cause of AF recurrence. Novel ablation tools, such as balloon technologies or alternative energy sources, might help to overcome this limitation. Patients with non-paroxysmal AF and with AF recurrence might benefit from alternative ablation strategies. However, further studies are warranted to further improve our knowledge of the underlying mechanisms of AF and to obtain long-term clinical outcomes on new ablation techniques.

Local impedance guides catheter ablation in patients with ventricular tachycardia.

AIMS: Catheter contact and local tissue characteristics are relevant information for successful radiofrequency current (RFC)-ablation. Local impedance (LI) has been shown to reflect tissue characteristics and lesion formation during RFC-ablation. Using a novel ablation catheter incorporating three mini-electrodes, we investigated LI in relation to generator impedance (GI) in patients with ventricular tachycardia (VT) and its applicability as an indicator of effective RFC-ablation. METHODS AND RESULTS: Baseline impedance, Δimpedance during ablation and drop rate (Δimpedance/time) were analyzed for 625 RFC-applications in 28 patients with recurrent VT undergoing RFC-ablation. LI was lower in scarred (87.0 Ω [79.0-95.0]) compared to healthy myocardium (97.5 Ω ([82.75-111.50]; P = .03) while GI did not differ between scarred and healthy myocardium. ΔLI was higher (18 Ω [9.4-26.0]) for VT-terminating as compared to non-terminating RFC-ablation (ΔLI 13 Ω [8.85-18.0]; P = .03), but did not differ for ΔGI between terminating vs nonterminating RFC-ablation. Correspondingly, LI drop rate was higher for RFC-ablation terminating the VT compared with RFC-ablation not terminating the VT (0.63 Ω/s [0.52-0.76] vs 0.32 Ω [0.20-0.58]; P = .008) while there was no difference for GI drop rate. ΔLI was higher in patients with nonischemic cardiomyopathy vs patients with ischemic cardiomyopathy (16 Ω [11.0-20.0] vs 11.0 Ω [7.85-17.00]; P = .003). CONCLUSION: Our findings suggest that LI is a sensitive parameter to guide RFC-ablation in patients with VT. LI indicates differences in tissue characteristics and generally is higher in patients with nonischemic cardiomyopathy. Hence, the etiology of the underlying cardiomyopathy needs to be considered when adopting LI for monitoring catheter ablation of VT.