Narrow QRS ectopy with concealed connections from a para-Hisian origin to the proximal left fascicles.

INTRODUCTION: Catheter ablation of ectopy originating from the vicinity of the His bundle can be challenging. METHODS AND RESULTS: We report a case of a 33-year-old man with narrow QRS ectopy with preferential conduction from a para-Hisian origin to the proximal left fascicles, which was successfully eliminated by radiofrequency ablation in the right coronary cusp, guided by ultrahigh-resolution mapping of the His bundle, bundle branch, and fascicular electrograms. CONCLUSION: Some narrow QRS ectopy may originate from the vicinity of the conduction system, instead of the "true" conduction system, and have concealed connections from its origin to the conduction system.

The optimal slow pathway ablation site in atrioventricular nodal reentrant tachycardia cases with an inferiorly located His bundle.

INTRODUCTION: The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. METHODS AND RESULTS: In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior-to-inferior (SPSI), anterior-to-posterior (SPAP), and right-to-left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior-to-inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7 ± 6.4, 1.7 ± 6.4, 13.6 ± 12.3, and -1.0 ± 13.0 mm, respectively. The HISSI was positively correlated with SPSI (R2 = 0.62; P < .01) and SPAP (R2 = 0.22; P < .01), whereas it was not correlated with SPRL (R2 = 0.01; P = .65). The distance between the HIS and SP ablation site was 17.7 ± 6.4 mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI ≥ 13 mm) and low HIS group (HISSI < 13 mm) (0.10 ± 0.06 vs. 0.10 ± 0.06; P = .38). CONCLUSION: In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases.

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

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

The Japanese Catheter Ablation Registry (J-AB): Annual report in 2021.

The Japanese Catheter Ablation (J-AB) registry, started in August 2017, is a voluntary, nationwide, multicenter, prospective, observational registry, performed by the Japanese Heart Rhythm Society (JHRS) in collaboration with the National Cerebral and Cardiovascular Center using a Research Electronic Data Capture system. The purpose of this registry is to collect the details of target arrhythmias, the ablation procedures, including the type of target arrhythmias, outcomes, and acute complications in the real-world settings. During the year of 2021, we have collected a total of 89 609 procedures (mean age of 66.1 years and 65.9% male) from 506 participant hospitals. Detailed data are shown in Figures and Tables.

A-V-V-A response to single atrial premature depolarization in a narrow QRS tachycardia: What is the mechanism?

We present an atypical response to single atrial premature depolarization (APD) in a long RP' tachycardia. APD advanced the His-bundle potential immediately after it and resulted in a VA block; however, tachycardia persisted and consequently exhibited an A-V-V-A response. We propose the mechanism for an A-V-V-A response to APD in a long RP' tachycardia.

Incidence, distribution, and electrogram characteristics of endocardial-epicardial connections identified by ultra-high-resolution mapping during a left atrial posterior wall isolation of atrial fibrillation.

PURPOSE: The left atrial posterior wall (LAPW) can be a target for atrial fibrillation (AF) catheter ablation but is sometimes difficult to completely isolate due to the presence of endocardial-epicardial connections. We aimed to investigate the incidence and distribution of epicardial residual connections (epi-RCs) and the electrogram characteristics at epi-RC sites during an initial LAPW isolation. METHODS: We retrospectively studied 102 AF patients who underwent LAPW mapping before and after a first-pass linear ablation along the superior and inferior LAPW (pre-ablation and post-ablation maps) using an ultra-high-resolution mapping system (Rhythmia, Boston Scientific). RESULTS: Epi-RCs were observed in 41 patients (40.2%) and were widely distributed in the middle LAPW area and surrounding it. The sites with epi-RCs had a higher bipolar voltage amplitude and greater number of fractionated components than those without (median, 1.09 mV vs. 0.83 mV and 3.9 vs. 3.4 on the pre-ablation map and 0.38 mV vs. 0.27 mV and 8.5 vs. 4.2 on the post-ablation map, respectively; P < 0.001). Receiver operating characteristic analyses demonstrated that the number of fractionated components on the post-ablation map had a larger area under the curve of 0.847 than the others, and the sensitivity and specificity for predicting epi-RCs were 95.4% and 62.1%, respectively, at an optimal cutoff of 5.0. CONCLUSIONS: Among the patients with epi-RCs after a first-pass LAPW linear ablation, areas with a greater number of fractionated components (> 5.0 on the post-ablation LAPW map) may have endocardial-epicardial connections and may be potential targets for touch-up ablation to eliminate the epi-RCs.

Noncontact Charge Density Mapping-Guided Ablation of Persistent Atrial Fibrillation With a Multiple Trigger-Based Mechanism.

We present a case of radiofrequency catheter ablation of persistent atrial fibrillation (AF) with a trigger-based mechanism, guided by novel noncontact charge density mapping, which resulted in the simultaneous achievement of the termination of AF and complete elimination of multiple triggers that induced repeated recurrences of AF immediately after cardioversion. (Level of Difficulty: Advanced.).

Ethanol infusion therapy for peri-mitral atrial tachycardia through the Marshall bundle with electrical irrelevance of left atrial appendage and mitral isthmus.

A 62-year-old man with a history of catheter ablation for atrial fibrillation and atrial tachycardia (AT) received a line of block of the mitral isthmus (MI) and electrical isolation of the left atrial appendage (LAA). Upon entrainment pacing, AT recurred and was diagnosed as peri-mitral AT (PMAT) with electrical irrelevance of MI, LAA, and left pulmonary vein, having a critical isthmus identified as Marshall bundle (MB). MB was then infused with ethanol, leading to the successful treatment of the PMAT.

Intra-septal radiofrequency ablation within the transseptal puncture hole targeting an interatrial connection during a bi-atrial tachycardia.

A 74-year-old man after multiple mitral valve surgeries underwent catheter ablation of a bi-atrial tachycardia (BiAT). Ultra-high resolution activation mapping exhibited a reentrant circuit propagating around the inferior to anterior mitral annulus and right atrial (RA) septum with two interatrial connections. At the transeptal puncture site, continuous fractionated electrograms were recorded during the BiAT, and entrainment pacing revealed a post-pacing interval similar to the tachycardia cycle length, which suggested that the interatrial conduction from the RA to the left atrium (LA) was located just at the transseptal puncture site. A radiofrequency application inside the transseptal puncture hole could successfully eliminate the BiAT. The ablation target for BiATs propagating around the mitral annulus and RA septum is generally the anatomical mitral isthmus (MI). Since the present case had multiple incisions on both the RA and LA septum due to mitral valve surgeries, there was the possibility of the occurrence of a BiAT including the RA and LA septum after performing an MI linear ablation. Therefore, the preferable ablation target for the BiAT in the present case appeared to be the interatrial connection. Ultra-high resolution detailed mapping not only on the atrial endocardium but also in the transseptal puncture hole may be useful for identifying a critical interatrial connection of BiAT circuits.

Unusual QRS complexes associated with the simultaneous presence of a right-sided accessory pathway, fasciculoventricular pathway, and incomplete right bundle branch block.

A 52-year-old man presented with delta waves on a body surface electrocardiogram, which suggested the presence of a right-sided accessory pathway (AP). Patients with right-sided APs generally have an rS pattern in leads V1-2, while he had an rS in lead V1 but an Rs in lead V2, which could not rule out the possibility of the presence of a septal AP or fasciculoventricular pathway (FVP). On the other hand, patients with septal APs or FVPs generally have a QS pattern in lead V1 instead of an rS pattern. An electrophysiological study demonstrated that the simultaneous presence of a right-sided posterolateral AP and FVP with incomplete right bundle branch block (ICRBBB) generated those unusual QRS complexes. The FVP arose distal to the site with ICRBBB, and the ICRBBB delayed the initiation of the FVP conduction. The delayed QS and Rs waves in leads V1-2 generated by the FVP conduction with ICRBBB appeared to produce rS and Rs patterns in leads V1-2, respectively. A radiofrequency application along the posterolateral tricuspid annulus eliminated the right-sided AP conduction. If the localization of APs based on the QRS morphology is difficult, multiple APs or an FVP with a conduction system disturbance should be noted. Learning objective: Patients with right-sided posterolateral accessory pathways (APs) generally have an rS pattern in lead V2, while patients with fasciculoventricular pathways (FVPs) generally have a QS pattern in lead V1. The present case with a suspected right-sided posterolateral AP had unusual QRS complexes, an rS in lead V1, Rs in lead V2, and monophasic R in leads V3-6, which were associated with the simultaneous presence of a right-sided posterolateral AP, FVP, and incomplete right bundle branch block.

Provocation and Localization of Arrhythmogenic Triggers from Persistent Left Superior Vena Cava in Patients with Atrial Fibrillation.

BACKGROUND: Although pulmonary vein isolation (PVI) is an established procedure for atrial fibrillation (AF), non-PV foci play a crucial role in AF recurrence. Persistent left superior vena cava (PLSVC) has been reported as critical non-PV foci. However, the effectiveness of provocation of AF triggers from PLSVC remains unclear. This study was designed to validate the usefulness of provoking AF triggers from PLSVC. METHODS: This multicenter retrospective study included 37 patients with AF and PLSVC. To provoke triggers, AF was cardioverted, and re-initiation of AF was monitored under high-dose isoproterenol infusion. The patients were divided into two groups: those whose PLSVC had arrhythmogenic triggers initiating AF (Group A) and those whose PLSVC did not have triggers (Group B). Group A underwent isolation of PLSVC after PVI. Group B received PVI only. RESULTS: Group A had 14 patients, whereas Group B had 23 patients. After a 3-year follow-up, no difference in the success rate for maintaining sinus rhythm was observed between the two groups. Group A was significantly younger and had lower CHADS2-VASc scores than Group B. CONCLUSIONS: The provocation of arrhythmogenic triggers from PLSVC was effective for the ablation strategy. PLSVC electrical isolation would not be necessary if arrhythmogenic triggers are not provoked.

The Japanese Catheter Ablation Registry (J-AB): Annual report in 2020.

The Japanese Catheter Ablation (J-AB) registry, started in August 2017, is a voluntary, nationwide, multicenter, prospective, observational registry, performed by the Japanese Heart Rhythm Society (JHRS) in collaboration with the National Cerebral and Cardiovascular Center using a Research Electronic Data Capture system. The purpose of this registry is to collect the details of target arrhythmias, the ablation procedures, including the type of target arrhythmias, outcomes, and acute complications in real-world settings. During the year 2020, we have collected a total of 84 591 procedures (mean age of 65.8 years and 66.6% male) from 466 participant hospitals. Detailed data were shown in Figures and Tables.

Bilateral Cardiac Sympathetic Denervation for Treatment-Resistant Ventricular Arrhythmias in Heart Failure Patients with a Reduced Ejection Fraction.

The sympathetic nervous system plays an important role in life-threatening ventricular arrhythmias (VAs). Bilateral cardiac sympathetic denervation (BCSD) is performed for refractory VAs. We sought to assess our institutional experience with BCSD in managing treatment-resistant monomorphic ventricular tachycardia (MMVT) in heart failure patients with a reduced ejection fraction (HFrEF).Four patients with HFrEF (EF 30.0 ± 8.2%, New York Heart Association [NYHA] class IV 1) underwent BCSD for MMVT (VT storm 3, repetitive VT requiring implantable cardioverter defibrillator [ICD] therapy 1) refractory to antiarrhythmic drugs, catheter ablation and ICD therapy. BCSD was effective for suppressing VT in 3 patients for whom deep sedation was effective for suppressing VT. One patient remained alive after 14 months of follow-up without episodes of VT. One patient died of acute myocardial infarction before discharge and 1 patient died from unknown cause at 3 days post-discharge. In contrast, BCSD was completely ineffective for suppressing VT in a patient with NYHA class IV for whom deep sedation and stellate ganglion block were ineffective. This patient died on the 10th post-CSD day, despite left ventricular assist device implantation. In all cases, BCSD was successfully performed without procedure-related complications.Despite the limited number of cases, our results showed that BCSD in patients with HFrEF suppressed refractory MMVT in acute-phase except for a patient with NYHA class IV; however, the prognoses were not good. BCSD may be a treatment option at an earlier stage of NYHA and a bridge to orthotopic heart transplantation, even if BCSD is effective for suppressing VAs.

Dual atrioventricular nodal non-reentrant tachycardia: Various atrioventricular conduction responses to atrioventricular simultaneous pacing.

BACKGROUND: Specific pacing methods to unmask the existence of the dual atrioventricular (AV) nodal pathway in patients with dual AV nodal non-reentrant tachycardia remain to be established. OBJECTIVE: This study aimed to determine the electrophysiological characteristics of dual AV nodal non-reentrant tachycardia by its responses to specific pacing methods. METHODS: Five patients diagnosed as having dual AV nodal non-reentrant tachycardia were retrospectively investigated. RESULTS: Atrial pacing could not induce the clinical tachycardia as continuous double firing in any of the 5 patients, but did induce sudden prolongation of the A-H interval as the linking phenomenon in 1 patient. A single atrial extrastimulation after sinus excitations was performed without interruption of double firing in 1 patient, and it induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals. The pacing method of AV simultaneous basic pacing preceding atrial programmed extrastimulation did not allow interruptions of double firing during the basic drive trains and induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals in all 5 patients, even in 1 patient without inducibility of the clinical tachycardia in the catheterization laboratory. The double ventricular response phenomenon within the limited range of the extrastimulus intervals may be based on the existence of the dual AV nodal pathway with concealed retrograde penetration. CONCLUSION: The AV simultaneous basic pacing preceding atrial programmed extrastimulation method consistently and reproducibly unmasked the existence of the dual AV nodal pathway as the double ventricular response phenomenon in patients with dual AV nodal non-reentrant tachycardia.

Local impedance measurements during contact force-guided cavotricuspid isthmus ablation for predicting an effective radiofrequency ablation.

Background: An ablation catheter capable of contact force (CF) and local impedance (LI) monitoring (IntellaNav StablePoint, Boston Scientific) has been recently launched. We evaluated the relationship between the CF and LI values during radiofrequency catheter ablation (RFCA) along the cavotricuspid isthmus (CTI). Methods: Fifty consecutive subjects who underwent a CTI-RFCA using IntellaNav StablePoint catheters were retrospectively studied. The initial CF and LI at the start of the RF applications and mean CF and minimum LI during the RF applications were measured. The absolute and percentage LI drops were calculated as the difference between the initial and minimum LIs and 100 × absolute LI drop/initial LI, respectively. Results: We analyzed 602 first-pass RF applications. A weak correlation was observed between the initial CF and LI (r = 0.13) and between the mean CF and LI drops (r = 0.22). The initial LI and absolute and percentage LI drops were greater at effective ablation sites than ineffective ablation sites (median, 151 vs. 138 Ω, 22 vs. 14 Ω, and 14.4% vs. 9.9%; p < .001), but the initial and mean CF did not differ. At optimal cutoffs of 21 Ω and 10.8% for the absolute and percentage LI drops according to the receiver-operating characteristic analysis, the sensitivity, and specificity for predicting an effective ablation were 57.4% and 88.9% and 80.0%, and 61.1%, respectively. Conclusions: The effective sites during the CF-guided CTI-RFCA had greater initial LI and LI drops than the ineffective sites. Absolute and percentage LI drops of 21 Ω and 10.8% may be appropriate targets for an effective ablation.

A confluent non-enhanced dark core on serial late gadolinium enhancement imaging after a moderator band-ventricular tachycardia ablation.

A 77-year-old man underwent radiofrequency catheter ablation of incessant ventricular arrhythmias (VAs) originating from the right ventricular (RV) moderator band (MB). Activation mapping during the VAs exhibited a centrifugal pattern with the earliest activation site (EAS) on the RV septum. A local impedance (LI)-guided radiofrequency application targeting the EAS with a maximum power output of 50W successfully eliminated the VAs and resulted in an LI drop of up to 35 Ω. Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) on the day after the ablation procedure demonstrated a confluent non-enhanced dark core on the RV septal portion of the MB. On the LGE-MRI two months after the procedure, the dark core region became contracted and instead the peripheral region surrounding the dark core exhibited a bright enhancement. The size of the dark core and peripheral enhanced regions on the LGE-MRI remained almost unchanged two months to two years after the procedure. He had no VA recurrences during a two-year follow-up period. Previous LGE-MRI studies reported that an ablated area within healthy ventricular myocardium exhibits a bright homogenous enhancement during the post-ablation chronic phase, while that within ventricular scar tissue exhibits a confluent non-enhanced dark core. This case suggested the presence of a dark core with a peripheral enhancement corresponding to the ablated area within the healthy myocardium of the RV-MB. LGE-MRI may be useful for accurately detecting RF ablation lesions on the RV-MB and visualizing the serial changes in the LGE-MRI characteristics from the post-ablation acute to chronic phases.