Prognosis of patients in end-stage heart failure with atrial fibrillation treated with ablation: Insights from CASTLE-HTx.

BACKGROUND: The CASTLE-HTx trial demonstrated the benefit of atrial fibrillation (AF) ablation compared with medical therapy in decreasing mortality, need for left ventricular assist device implantation, or heart transplantation (HTx) in patients with end-stage heart failure (HF). OBJECTIVE: This analysis aimed to identify risk factors related to adverse outcomes in patients with end-stage HF and to assess the impact of ablation. METHODS: The CASTLE-HTx protocol randomized 194 patients with end-stage HF and AF to ablation vs medical therapy. We identified left ventricular ejection fraction <30%, New York Heart Association class ≥III, and AF burden >50% as predictors for the primary end point. The CASTLE-HTx risk score assigned weights to these risk factors. Patients with a risk score ≥3 were identified as high risk. RESULTS: The patients were assigned to low-risk (89 [45.9%]) and high-risk (105 [54.1%]) groups. After a median follow-up of 18 months, a primary end point event occurred in 6 and 31 patients of the low- and high-risk groups (hazard ratio, 4.98; 95% confidence interval, 2.08-11.9). The incidence rate (IR) difference between ablation and medical therapy was much larger in high-risk patients (8/49 [IR, 11.4] vs 23/56 [IR, 36.1]) compared with low-risk patients (2/48 [IR, 2.6] vs 4/41 [IR, 6.3]). The IR difference for ablation was significantly higher in high-risk patients (24.69) compared with low-risk patients (3.70). CONCLUSION: The absolute benefit of ablation is more pronounced in high-risk patients, but low-risk patients may also benefit. The CASTLE-HTx risk score identifies patients with end-stage HF who will particularly benefit from ablation.

Atrial fibrillation ablation workflow optimization facilitated by high-power short-duration ablation and high-resolution mapping.

AIMS: Pulmonary vein isolation (PVI) for catheter ablation of atrial fibrillation (AF) is a time-demanding procedure. High-power short-duration (HPSD) ablation protocols and high-density mapping catheters have recently been introduced to clinical practice. We investigated the impact of high-density mapping and HPSD ablation protocols on procedural timing, efficacy, and safety by comparing different standardized set-ups. METHODS AND RESULTS: Three electrophysiology (EP) laboratory set-ups were analysed: (i) circular catheter for mapping and HPSD ablation with 30/35 W guided by an ablation index (AI); (ii) pentaspline catheter for mapping an HPSD ablation with 50 W guided by an AI; and (iii) pentaspline catheter for mapping and HPSD ablation with 90 W over 4 s using a novel ablation catheter. All patients underwent PVI without additional left atrial ablation strategies. Procedural data and operating intervals in the EP laboratory were systematically analysed. Three hundred seven patients were analysed (30/35 W AI: n = 102, 50 W AI: n = 102, 90 W/4 s: n = 103). Skin-to-skin times [105.3 ± 22.7 (30/35 W AI) vs. 81.4 ± 21.3 (50 W AI) vs. 69.5 ± 12.2 (90 W/4 s) min, P ≤ 0.001] and total laboratory times (132.8 ± 42.1 vs. 107.4 ± 25.7 vs. 95.2 ± 14.0 min, P < 0.001) significantly differed among the study groups. Laboratory interval analysis revealed significant shortening of mapping and ablation times. Arrhythmia-free survival after 12 months was not different among the study groups (log-rank P = 0.96). CONCLUSION: The integration of high-density mapping and HPSD protocols into an institutional AF ablation process resulted in reduced procedure times without compromising safety or efficacy.

Successful ablation of Purkinje ectopy-triggered ventricular fibrillation storm in a patient with orthotopic heart transplantation and severe SARS-CoV-2 pneumonia: a case report.

Background: Catheter ablation is one of the most effective treatment options for patients with drug-refractory, scar-related monomorphic ventricular tachycardia (VT). In selected cases, catheter ablation also plays an important role in treatment of polymorphic VT (PMVT) and/or ventricular fibrillation (VF). Rarely, premature ventricular contractions (PVCs) originating from the Purkinje network can induce PMVT/VF. Ablation and elimination of these PVCs can prevent VF recurrences. Case summary: A 41-year-old patient with a history of orthotopic heart transplantation (HTX) 8 years before admission and newly diagnosed SARS-CoV-2 pneumonia was referred to our centre after experiencing several episodes of drug-refractory VF. An electrophysiological study showed ectopy-triggered VF originating from the anterior and posterior fascicles of the left bundle branch (LBB). Ablation of these PVCs from the LBB led to complete elimination of VF. A subcutaneous implantable cardioverter defibrillator was implanted as secondary prophylaxis. During the observation period of 6 months, no VF recurrence was observed. Conclusion: Identifying and eliminating the trigger (PVCs) can be life-saving and prevent VF in the specific cohort of HTX patients. High-density mapping using multipolar catheters with microelectrodes contributes significantly to our understanding of tachycardia mechanisms.

Catheter Ablation in End-Stage Heart Failure with Atrial Fibrillation.

BACKGROUND: The role of catheter ablation in patients with symptomatic atrial fibrillation and end-stage heart failure is unknown. METHODS: We conducted a single-center, open-label trial in Germany that involved patients with symptomatic atrial fibrillation and end-stage heart failure who were referred for heart transplantation evaluation. Patients were assigned to receive catheter ablation and guideline-directed medical therapy or medical therapy alone. The primary end point was a composite of death from any cause, implantation of a left ventricular assist device, or urgent heart transplantation. RESULTS: A total of 97 patients were assigned to the ablation group and 97 to the medical-therapy group. The trial was stopped for efficacy by the data and safety monitoring board 1 year after randomization was completed. Catheter ablation was performed in 81 of 97 patients (84%) in the ablation group and in 16 of 97 patients (16%) in the medical-therapy group. After a median follow-up of 18.0 months (interquartile range, 14.6 to 22.6), a primary end-point event had occurred in 8 patients (8%) in the ablation group and in 29 patients (30%) in the medical-therapy group (hazard ratio, 0.24; 95% confidence interval [CI], 0.11 to 0.52; P<0.001). Death from any cause occurred in 6 patients (6%) in the ablation group and in 19 patients (20%) in the medical-therapy group (hazard ratio, 0.29; 95% CI, 0.12 to 0.72). Procedure-related complications occurred in 3 patients in the ablation group and in 1 patient in the medical-therapy group. CONCLUSIONS: Among patients with atrial fibrillation and end-stage heart failure, the combination of catheter ablation and guideline-directed medical therapy was associated with a lower likelihood of a composite of death from any cause, implantation of a left ventricular assist device, or urgent heart transplantation than medical therapy alone. (Funded by Else Kröner-Fresenius-Stiftung; CASTLE-HTx ClinicalTrials.gov number, NCT04649801.).

Impact of pulmonary vein anatomy and ostial dimensions on long-term outcome after single-shot device-guided cryoablation for paroxysmal atrial fibrillation.

BACKGROUND: Cryoballoon (CB)-guided pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). This observational study aimed to assess the role of individual anatomical characteristics to predict long-term freedom from arrhythmia recurrence after CB-guided PVI for paroxysmal AF (PAF). METHODS: Three hundred fifty three consecutive patients (58 ± 11 years, 56% males), undergoing PVI between 2012 and 2018 were analysed. Individual pulmonary vein (PV) anatomy was assessed using preprocedural cardiac magnetic resonance imaging (MRI). For each PV, the cross-sectional area (CSA) was calculated. The impact of PV characteristics and CSA on long-term AF-free survival was evaluated. RESULTS: Acute PVI was achieved in all patients. Two hundred twenty-three patients (63%) had a normal PV anatomy (2 left- and 2 right-sided PV). Variant PV anatomy was present in 130 patients (37%). During the observation period of 48 months, AF-recurrence was documented in 167 patients (47 %). Patients with AF-recurrence presented with significantly enlarged right-sided PVs and left superior PVs (LSPVs) (p < 0.001). The presence of left common PVs (LCPVs) (n = 75, Log-rank p < 0.001) as well as right variant PVs (n = 35, Log rank p < 0.001) was associated with a significantly impaired long-term AF-free survival rate as compared to patients with normal PV characteristics. CONCLUSION: Variant PV anatomy is a good predictor for AF-recurrence. A correlation between an enlarged CSA of right-sided PVs as well as LSPVs and AF-recurrence was documented.

First clinical experience using the DiamondTemp catheter and a novel omnipolar high-resolution mapping system for atrial fibrillation ablation.

BACKGROUND: The DiamondTemp (DT) radiofrequency ablation (RFA) catheter has been introduced as a new tool for atrial fibrillation (AF) ablation. The new technology allows for temperature-controlled irrigated ablation and real-time lesion assessment. Recently, the EnSite X mapping system became commercially available allowing for omnipolar and ultra-high-resolution mapping. We aimed to assess the feasibility of the new DT RFA catheter in performing AF ablation procedures in conjunction with the novel EnSite X system under routine clinical conditions. METHODS: We analyzed data from 10 consecutive patients who underwent AF ablation using the DT RFA catheter guided by EnSite X. Procedural data and short-term follow-up were assessed as well as potential technical issues. RESULTS: Nine out of 10 patients underwent de-novo pulmonary vein isolation (PVI), and 1 patient underwent repeat ablation. First-pass isolation was observed in 7/10 patients. Total procedure duration (skin-to-skin) was 88.9 ± 30.1 min, and left atrium dwell time was 70 ± 22.3 min. The mean number of RF applications needed for PVI and additional ablation was 70.52 ± 26.70. The HD Grid SE mapping catheter was utilized in 8 patients and the Advisor SE in 2 patients. Bidirectional block of the applied lines was achieved in all patients. No steam pops were observed, and no intraprocedural complications occurred. CONCLUSIONS: This first clinical series demonstrated that temperature-controlled irrigated ablation in combination with the novel omnipolar and high-resolution mapping system resulted in rapid, efficient, and durable lesion formation under routine clinical conditions. Randomized controlled trials are needed to elucidate the impact on lesion formation, long-term outcomes, and reproducibility of our initial findings.

Baroreflex activation therapy in advanced heart failure therapy: insights from a real-world scenario.

AIMS: Baroreflex activation therapy (BAT) is an innovative treatment option for advanced heart failure (HFrEF). We analysed patients' BAT acceptance and the outcome of BAT patients compared with HFrEF patients solely treated with a guideline-directed medical therapy (GDMT) and studied effects of sacubitril/valsartan (ARNI). METHODS: In this prospective study, 40 HFrEF patients (71 ± 3 years, 20% female) answered a questionnaire on the acceptance of BAT. Follow-up visits were performed after 3, 6, and 12 months. Primary efficacy endpoints included an improvement in QoL, NYHA class, LVEF, HF hospitalization, NT-proBNP levels, and 6MHWD. RESULTS: Twenty-nine patients (73%) showed interest in BAT. Ten patients (25%) opted for implantation. BAT and BAT + ARNI patients developed an increase in LVEF (BAT +10%, P-value (P) = 0.005*; BAT + ARNI +9%, P = 0.049*), an improved NYHA class (BAT -88%, P = 0.014*, BAT + ARNI -90%, P = 0.037*), QoL (BAT +21%, P = 0.020*, BAT + ARNI +22%, P = 0.012*), and reduced NT-proBNP levels (BAT -24%, P = 0.297, BAT + ARNI -37%, P = 0.297). BAT HF hospitalization rates were lower (50%) compared with control group patients (83%) (P = 0.020*). CONCLUSIONS: Although BAT has generated considerable interest, acceptance appears to be ambivalent. BAT improves outcome with regard to LVEF, NYHA class, QoL, NT-proBNP levels, and HF hospitalization rates. BAT + ARNI resulted in more pronounced effects than ARNI alone.

EASY-WPW: a novel ECG-algorithm for easy and reliable localization of manifest accessory pathways in children and adults.

AIMS: Accessory pathway (AP) ablation is a standard procedure for the treatment of Wolff-Parkinson-White syndrome (WPW). Twelve-lead electrocardiogram (ECG)-based delta wave analysis is essential for predicting ablation sites. Previous algorithms have shown to be complex, time-consuming, and unprecise. We aimed to retrospectively develop and prospectively validate a new, simple ECG-based algorithm considering the patients' heart axis allowing for exact localization of APs in patients undergoing ablation for WPW. METHODS AND RESULTS: Our multicentre study included 211 patients undergoing ablation of a single manifest AP due to WPW between 2013 and 2021. The algorithm was developed retrospectively and validated prospectively by comparing its efficacy to two established ones (Pambrun and Arruda). All patients (32 ± 19 years old, 47% female) underwent successful pathway ablation. Prediction of AP-localization was correct in 197 patients (93%) (sensitivity 92%, specificity 99%, PPV 96%, and NPV 99%). Our algorithm was particularly useful in correctly localizing antero-septal/-lateral (sensitivity and specificity 100%) and posteroseptal (sensitivity 98%, specificity 92%) AP in proximity to the tricuspid valve. The accuracy of EASY-WPW was superior compared to the Pambrun (93% vs. 84%, P = 0.003*) and the Arruda algorithm (94% vs. 75%, P < 0.001*). A subgroup analysis of children (n = 58, 12 ± 4 years old, 55% female) revealed superiority to the Arruda algorithm (P < 0.001*). The reproducibility of our algorithm was excellent (Ï°>0.8; P < 0.001*). CONCLUSION: The novel EASY-WPW algorithm provides reliable and accurate pre-interventional ablation site determination in WPW patients. Only two steps are necessary to locate left-sided AP, and three steps to determine right-sided AP.

Catheter ablation in patients with ventricular fibrillation by purkinje de-networking.

Background: Ventricular fibrillation (VF) is a leading cause of cardiovascular death worldwide. However, recurrence rates of arrhythmia are high leading to mortality and morbidity. Recently, Purkinje fibers have been identified as potential sources of VF initiation and maintenance. Aim: The study analyzes the feasibility and effectiveness of catheter ablation in patients with recurrent VF by specific Purkinje de-networking (PDN). Methods: Consecutive patients with recurrent VF undergoing PDN were included in this observational study. The procedural endpoint was the non-inducibility of sustained ventricular arrhythmia. A three-dimensional -anatomical mapping was conducted, and the specific cardiac conduction system and Purkinje fibers were tagged. All detectable Purkinje signals were ablated in the left ventricle (LV). Additional right ventricular (RV) PDN was performed in case of VF inducibility after LV ablation. Follow-up was performed by patient visits at our outpatient clinic including device interrogation and by telephone interviews. Results: Eight patients were included in the study. Six patients were females (75%); the median age during the procedure was 43 [37;57] years and the median body mass index was 24 [23;33] kg/m2. Four patients (50%) had known structural heart disease with two cases of ischemic cardiomyopathy and two cases of dilated cardiomyopathy. In four patients (50%), no underlying structural heart disease could be identified. The median LV ejection fraction was 42 ± 16.4%. All patients had an implantable cardioverter-defibrillator (ICD) prior to ablation with documentation of recurrent VF. The median number of ICD shocks before the ablation was 5 [3;7]. LV PDN was performed in all patients. In two patients (25%), an additional RV PDN was performed. Non-inducibility of any ventricular arrhythmia was achieved in all patients after PDN. Two patients showed complete left bundle branch block post-ablation. The median follow-up duration was 264 [58;421] days. Two patients (25%) experienced ventricular arrhythmia recurrence with recurrent ICD-shock delivery. One patient died during follow-up with an unknown cause of death. Six patients (75%) experienced no arrhythmia recurrence during follow-up. Conclusion: Purkinje de-networking represents a novel treatment option for patients with recurrent VF without arrhythmia substrate or specific arrhythmia triggers with promising results in terms of efficiency and feasibility. Larger and more prospective studies are needed for a systematic evaluation.

AV-node isolation as an alternative to AV-node ablation in patients undergoing pace & ablate strategy.

INTRODUCTION: Atrioventricular (AV)-node ablation (AVNA) is a common therapy option for rate control strategy of permanent atrial fibrillation (AF). We hypothesized that isolation of the AV nodal isolation (AVNI) is associated with a more frequent preservation of an adequate escape rhythm compared to AVNA. METHODS: This retrospective study included 20 patients with therapy-refractory AF being treated with AVNI and 40 historical AVNA-controls. In AVNI the AV-node region was mapped using a 3D mapping system. Ablation was performed around the previously mapped HIS-cloud regions isolating the atrium from the AV-node. In the AVNI group, ablation was performed with irrigated tip ablation catheter in all cases. The two approaches were compared regarding rate of escape rhythm, delta QRS, and procedural data. RESULTS: The number of patients with adequate escape rhythm in AVNI was significantly superior to AVNA immediately postoperative (90% vs. 40%, p < 0.01) and during follow-up (77% vs. 36%, p < 0.05). The median change in QRS width was 0 ms in AVNI versus +26 ms in AVNA (p < 0.01). Thirty percent new bundle branch blocks in AVNA were observed compared to 0% in AVNI (p < 0.01). In the AVNI group, fluoroscopy time and total dose area product were significantly lower (p < 0.01). CONCLUSION: The present study suggests that AV-node isolation using 3D navigation mapping system is a feasible and effective alternative to conventional AVNA. The precise application of radiofrequency lesions preserves a stable AV-junctional rhythm.

Direct comparison of two 50 W high power short duration approaches-Temperature- versus ablation index-guided radiofrequency ablation for atrial fibrillation.

INTRODUCTION: Approaches applying higher energy levels for shorter periods (high power short duration, HPSD) to improve lesion formation for atrial fibrillation (AF) ablation have been introduced. This single-center study aimed to compare the efficacy, safety, and lesion formation using the novel DiamondTemp (DT) catheter or an ablation index (AI)-guided HPSD ablation protocol using a force-sensing catheter with surround-flow irrigation. METHODS: One hundred thirteen consecutive patients undergoing radiofrequency-guided catheter ablation (RFCA) for AF were included. Forty-five patients treated with the DT catheter (50 W, 9 s), were compared to 68 consecutive patients undergoing AI-guided ablation (AI anterior 550; AI posterior 400) adherent to a 50 W HPSD protocol. Procedural data and AF recurrence were evaluated. RESULTS: Acute procedural success was achieved in all patients (n = 113, 100%). DT-guided AF ablation was associated with a longer mean procedure duration (99.10 ± 28.30 min vs. 78.24 ± 25.55, p < .001) and more RF applications (75.24 ± 30.76 min vs. 61.27 ± 14.06, p = .019). RF duration (792.13 ± 311.23 s vs. 1035.54 ± 287.24 s, p < .001) and fluoroscopy dose (183.81 ± 178.13 vs. 295.80 ± 247.54 yGym2 , p = .013) were lower in the DT group. AI-guided HPSD was associated with a higher AF-free survival rate without reaching statistical significance (p = .088). Especially patients with PERS AF (p = .009) as well as patients with additional atrial arrhythmia substrate (p = .002) benefited from an AI-guided ablation strategy. CONCLUSION: Temperature- and AI- controlled HPSD RFCA using 50 W was safe and effective. AI-guided HPSD ablation seems to be associated with shorter procedure durations and fewer RF applications. Particularly in advanced AF, freedom from AF-recurrence may be improved using an AI-guided HPSD approach.

Magnetic-Resonance-Imaging-Based Left Atrial Strain and Left Atrial Strain Rate as Diagnostic Parameters in Cardiac Amyloidosis.

Aims: The present study aims to evaluate magnetic-resonance-imaging (MRI)-assessed left atrial strain (LAS) and left atrial strain rate (LASR) as potential parameters for the diagnosis of cardiac amyloidosis (CA), the distinction of clinical subtypes and differentiation from other cardiomyopathies. Methods and results: LAS and LASR were assessed by MRI feature tracking in patients with biopsy-proven CA. LAS and LASR of patients with CA were compared to healthy subjects and patients with hypertrophic cardiomyopathy. LAS and LASR were also analyzed concerning differences between patients with transthyretin (ATTR) and light chain amyloidosis (AL). A total of 44 patients with biopsy-proven CA, 19 patients with hypertrophic cardiomyopathy and 24 healthy subjects were included. In 22 CA patients (50%), histological examination identified ATTR as CA subtype and AL in the remaining patients. No significant difference was observed for reservoir, conduit or booster LAS in patients with AL or ATTR. Reservoir LAS, conduit LAS and booster LAS were significantly reduced in patients with CA and HCM as compared to healthy subjects (p < 0.001). Reservoir LAS and booster LAS were significantly reduced in CA as compared to HCM patients (p < 0.001). A linear correlation was observed between LA global reservoir strain and LA-EF (p < 0.001, r = 0.5), conduit strain and global longitudinal LV strain (p < 0.001, r = 0.5), global booster strain rate and LA-EF (p < 0.001, r = 0.6) and between global booster strain rate and LA area at LVED (p < 0.0001, 0.5). Conclusions: LAS and LASR are severely impaired in patients with CA. The MRI-based assessment of LAS and LASR might allow non-invasive diagnosis and categorization of CA and its distinct differentiation from other hypertrophic phenotypes.

Combination of High-Density and Coherent Mapping for Ablation of Ventricular Arrhythmia in Patients with Structural Heart Disease.

The present study describes our experience with a new mapping approach for ventricular arrhythmia (VA) ablation in patients with structural heart disease (SHD). Consecutive patients undergoing catheter ablation for recurrent VA were analyzed. High-density mapping was conducted in all patients. In patients with inducible VA, local activation time (LAT) mapping and a novel vector-based mapping algorithm were implemented to analyze arrhythmia propagation. In case of focal tachycardia, the location of earliest activation was targeted. In VAs with re-entrant mechanisms, zones of slow conduction based on coherent mapping were ablated. Substrate modification was performed when pathologic electrograms were identified. Seventy-four patients were included. Sixty-five patients (87.8%) were male. Ischemic cardiomyopathy was the underlying disease in 35 patients (47.3%) and nonischemic cardiomyopathy was the underlying disease in 39 patients (52.7%). Mean left ventricular ejection fraction was 33.8 ± 9.9%. Non-inducibility of any VA was achieved in 70 patients (94.6%). Termination of VA was achieved in 93.5% of patients with stable VA. In 4 patients (5.4%), partial success was achieved. VA (p < 0.001), ATP (p < 0.001) and shock burden (p = 0.001) were significantly reduced after ablation. Mean arrhythmia-free survival after 12 months was 85.1 ± 4.7%. High-density mapping in combination with coherent mapping may facilitate the understanding of the tachycardia mechanism, providing targets for effective ablation.

[What the ablationist should know about pulmonary vein anatomy]. / Was muss der Abladeur zur Anatomie der Pulmonalvenen wissen?

The importance of anatomy in daily clinical practice of the interventional electrophysiologist is crucial, especially for pulmonary vein isolation which is a predominantly anatomy-based approach. Many anatomical and morphological studies focusing on this topic were published in last two decades. In this article we are refreshing the knowledge of anatomy and morphology of the pulmonary veins and present them from a clinical perspective.

A frozen decade: Ten years outcome of atrial fibrillation ablation using a single shot device for pulmonary vein isolation.

AIMS: Cryoballoon-guided pulmonary vein isolation (CB-PVI) for symptomatic atrial fibrillation (AF) has become an established treatment option with encouraging results in terms of safety and efficacy. Data reporting on long-term data beyond a follow-up (FU) period of 5 years is scarce. This prospective study aimed to evaluate very long-term outcome after CB-PVI for AF. METHODS: Data from consecutive patients treated with CB-PVI for symptomatic and drug refractory AF between 2005 and 2012 were analyzed. Patients with a FU of ≥9 years after index CB-PVI were included. All patients were continuously followed-up in our outpatient clinic. Arrhythmia recurrence was defined as AF or atrial tachycardia (AT) lasting >30 s beyond a 3-month blanking period. RESULTS: A total of 385 patients (71% male) were included. Mean age was 58 ± 10 years and paroxysmal AF was present in 93% of patients. Mean FU duration was 124 ± 24 months. At the end of the observational period, 73% of all patients were in stable sinus rhythm after a mean of 2 ± 0.8 ablation procedures. Patients with AF/AT recurrence were older (60 ± 8 vs. 57 ± 10 years; p = .019), had a higher CHA2 DS2 -Vasc Score (2.47 ± 1.46 vs. 1.98 ± 1.50; p = .01) and presented with a larger left atrium (LA)-diameter (43 ± 5.6 vs. 40 ± 5.1 mm; p = .002). The LA-diameter was also a significant predictor for AF/AT recurrence after CB-PVI (odds ratio: 0.939, 95% confidence interval: [0.886, 0.992], p = .03). CONCLUSIONS: CB-PVI as index procedure for AF ablation resulted in favorable long-term outcome in symptomatic AF. CB-PVI might be recommended as interventional therapy in patients with lower LA remodeling.

Development of a Visualization Deep Learning Model for Classifying Origins of Ventricular Arrhythmias.

BACKGROUND: Several algorithms have been proposed for differentiating the right and left outflow tracts (RVOT/LVOT) arrhythmia origins from 12-lead electrocardiograms (ECGs); however, the procedure is complicated. A deep learning (DL) model, a form of artificial intelligence, can directly use ECGs and depict the importance of the leads and waveforms. This study aimed to create a visualized DL model that could classify arrhythmia origins more accurately.Methods and Results: This study enrolled 80 patients who underwent catheter ablation. A convolutional neural network-based model that could classify arrhythmia origins with 12-lead ECGs and visualize the leads that contributed to the diagnosis using a gradient-weighted class activation mapping method was developed. The average prediction results of the origins by the DL model were 89.4% (88.2-90.6) for accuracy and 95.2% (94.3-96.2) for recall, which were significantly better than when a conventional algorithm is used. The ratio of the contribution to the prediction differed between RVOT and LVOT origins. Although leads V1 to V3 and the limb leads had a focused balance in the LVOT group, the contribution ratio of leads aVR, aVL, and aVF was higher in the RVOT group. CONCLUSIONS: This study diagnosed the arrhythmia origins more accurately than the conventional algorithm, and clarified which part of the 12-lead waveforms contributed to the diagnosis. The visualized DL model was convincing and may play a role in understanding the pathogenesis of arrhythmias.

News from the Cold Chamber: Clinical Experiences of POLARx versus Arctic Front Advance for Single-Shot Pulmonary Vein Isolation.

Cryoballoon (CB)-guided pulmonary vein isolation (PVI) represents a cornerstone in the treatment of atrial fibrillation (AF). Recently, a novel balloon-guided single shot device (POLARx, Boston Scientific) was designed. Our study aimed to compare the efficacy, safety and characteristics of the novel CB system with the established one (Arctic Front Advance (Pro), AFA, Medtronic). A total number of 596 patients undergoing CB-guided ablation for AF were included. 65 patients (65.0 ± 11.6, 31% female) undergoing PVI with the POLARx were compared to a cohort of 531 consecutive patients (63.0 ± 27.9, 25% female) treated with AFA. Acute PVI was achieved in all patients (n = 596, 100%). Total procedure duration (POLARx 113.3 ± 23.2 min, AFA 100.9 ± 21.3 min; p < 0.001) and fluoroscopy time (POLARx 10.5 ± 5.9 min, AFA 4.8 ± 3.6 min; p < 0.001) were significantly longer in the POLARx group. The POLARx balloon achieved significantly lower nadir temperatures (POLARx -57.7 ± 0.9 °C, AFA -45.1 ± 2.6 °C; p < 0.001) and a significantly higher percentage of pulmonary veins successfully isolated with the first freeze (p = 0.027 *). One major complication occurred in the POLARx (2%) and three (1%) in the AFA group. Both ablation systems are comparably safe and effective. AF ablation utilizing the POLARx system is associated with longer procedure and fluoroscopy times as well as lower nadir temperatures.