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The PRAETORIAN score was developed to evaluate the implant position and predict defibrillation success in patients implanted with a subcutaneous implantable cardioverter-defibrillator (S-ICD). However, usefulness of the PRAETORIAN score for Japanese patients is unknown.We evaluated usefulness of this score, which was determined by width of sub-coil fat, sub-generator fat, and anterior positioning of the S-ICD generator by post-operative chest X-ray, in consecutive 100 Japanese S-ICD implanted patients [78 men, median age 59 (IQR 46.5-67.0) years, median body mass index (BMI) 24.2 (21.3-27.2) kg/mThe median PRAETORIAN score was 30 (30-45) and 93 patients were classified as a low risk of conversion failure. The remaining seven were at an intermediate risk. Almost all patients were classified as an optimal pulse-generator position in the second and third steps of the PRAETORIAN score. The only difference observed was in the width of sub-coil fat in the first step. To further evaluate its significance, patients were divided into the Thicker group (sub-coil fat1 coil width, n = 19) and the Thinner group (sub-coil fat ≤1 coil width, n = 81). BMI and post-shock impedance were both higher in the Thicker group than in the Thinner group [27.1 (25.6-31.6) versus 23.1 (20.9-25.7) kg/mMost Japanese patients were classified as at low risk of conversion failure. The PRAETORIAN score may be useful for the evaluation of conversion failure in Japanese S-ICD implanted patients.

Objectives This study sought to reveal the characteristics and radiofrequency catheter ablation (RFCA) outcomes of multifocal His-Purkinje system (HPS) ventricular arrhythmias (VAs). Background The details of those VAs, especially the safety and efficacy of their RFCA treatment, remain unclear. Methods Thirty consecutive patients who underwent RFCA of focal HPS VAs between 2010 and 2016 (unifocal = 24, multifocal = 6) were studied by measuring the electrophysiological variables within the HPS. Results Multifocal premature ventricular contractions (n = 1) and ventricular fibrillation (VF) (n = 5) were identified in the left posterior (n = 6), anterior (n = 4), and septal fascicles (n = 1), as well as the basal left bundle branch (LBB) (n = 2) and right bundle branch (RBB) (n = 2). In 2 patients with unifocal VAs and 4 patients with multifocal VAs, preferential conduction from an origin within the proximal fascicle (n = 4) or LBB (n = 2) to ≤3 breakout sites in the distal fascicles occurred with split or fractionated Purkinje potentials and/or conduction block at the site of origin. Among the multifocal VAs, 11 fascicle VAs, 1 RBB VA, and 1 LBB VA were successfully ablated with fascicular and/or bundle branch block, and complete atrioventricular block (CAVB), respectively. In the remaining LBB VAs and RBB VAs, RFCA was abandoned to avoid CAVB. Recurrence of ablated VAs or the incidence of VF did not differ between the unifocal and multifocal HPS VAs. Freedom from any HPS VA after RFCA was significantly higher in the patients with unifocal VAs than in the patients with multifocal VAs (92% vs. 33%; p = 0.001). Conclusions Multifocal HPS VAs could occur and often present with preferential conduction from proximal origins to distal breakout sites within the HPS with abnormal Purkinje potentials and/or conduction properties. RFCA was effective but was limited by the risk of HPS impairment.

Introduction Preferential conduction from an origin to breakout sites can occur during ventricular arrhythmias (VAs) originating from the left ventricular papillary muscles (LVPMs). The purpose of this study was to investigate the incidence, electrophysiological characteristics, and relevance to radiofrequency catheter ablation (RFCA) of such a preferential conduction demonstrated by pace mapping. Methods and results We studied 34 consecutive patients undergoing RFCA of 40 LVPM VAs. Among 78 QRS morphologies during these VAs, pace mapping was performed for 67 QRS morphologies during 37 VAs, and revealed VA-matched pace maps (M-PMs) with a latency for 14 QRS morphologies during 11 VAs (30%). Among 47 QRS morphologies with activation mapping, RFCA at the earliest activation site (EAS) was successful in 39, but not successful in 8 despite M-PMs with no latency. In these cases, RFCA was successful at remote sites of the M-PMs with latency (n = 6) and a site located between the EAS and site of that with latency (n = 1). Among the remaining 31 QRS morphologies with pace mapping only, RFCA was successful at M-PM sites with no latency in 17, and at M-PMs sites with latency in 7. In 3 of those 7 QRS morphologies, M-PMs were recorded at multiple remote sites, and RFCA was not successful at M-PM sites with no latency (n = 2) or a shorter latency (n = 1). Conclusions When an M-PM with latency was recorded in LVPM VAs, RFCA at that site was highly successful. Attention should be paid to latency as well as the score during pace mapping of LVPM VAs.

Focal atrial tachycardias (ATs) from the septal cavotricuspid isthmus (CTI) occurring after successful CTI ablation can mimic typical atrial flutter (tAFL). This study investigated the incidence, and electrocardiographic and electrophysiological characteristics of these ATs. Among 1082 consecutive patients undergoing successful CTI ablation without any congenital heart diseases, 7 were diagnosed with focal ATs originating from the septal CTI that occurred a median of 74 days after the CTI ablation. The electrocardiographic characteristics of the ATs were similar to those of the tAFLs. The AT’s cycle length was never shorter than and often similar to that of tAFLs. The activation patterns along the tricuspid annulus during the ATs were the same as those of tAFLs in 4 patients with foci adjacent to the CTI line, and centrifugal from foci around the coronary sinus (CS) ostium in 3. Entrainment pacing from the lateral CTI during the ATs revealed a manifest fusion and long post-pacing interval. Entrainment pacing from the lateral CTI during the ATs revealed that the atrial electrograms recorded from the CS and high-lateral right atrium were orthodromically captured, while that from the proximal CS revealed that the atrial electrograms recorded from the CS and lateral right atrium were antidromically captured without manifest fusion. Focal intra-CTI ATs with a microreentrant mechanism very rarely occurred after successful CTI ablation. The electrocardiographic and electrophysiological characteristics of these ATs were similar to those of tAFLs. Overdrive pacing from the lateral CTI and proximal CS was helpful for distinguishing these ATs from recurrent tAFLs.

Successful cryoballoon pulmonary vein (PV) isolation sometimes requires cryoballoon occlusion techniques including a hockey stick maneuver (HSM) using a steerable sheath, whose steerable segment should be positioned in the left atrium (LA) for left inferior PV (LIPV) occlusion. However, a small LA can cause a transseptal puncture site adjacent to both the LIPV ostium and the LA roof, leading to the steerable segment out of the LA during the HSM. This report illustrates a modified HSM utilizing a steerable cryoballoon catheter, which might be considered as an option when the standard one is not operated as the LIPV occlusion technique.

Background The safety and efficacy of the contemporary atrial fibrillation (AF) ablation in patients with a recent or previous history of cardioembolic stroke (CS) or transient ischemic attack (TIA) remain to be established. Methods A total of 447 patients who underwent first-ever contact force (CF)-guided AF ablation with circumferential pulmonary vein isolation were included. Of these, 17 had CS or TIA within 6 months before ablation (Group 1), 30 more than 6 months before ablation (Group 2), and the other 400 without CS or TIA (Group 3). Procedural complications and recurrence of AF and atrial tachyarrhythmias were compared among the 3 groups. Results The mean age was 71 ± 7, 66 ± 9, and 61 ± 11 years in Groups 1, 2, and 3, respectively (p

Background The wearable cardioverter-defibrillator (WCD) has been expected to play a role as an effective bridge therapy to implantable cardioverter-defibrillator (ICD) implantation in patients at high risk of ventricular tachyarrhythmias (VA). Although WCD has been available since April 2014 in Japan, its usefulness remains unclear. Methods and results During the early period after hospitalization, patients at high risk of VA after excluding some elderly patients were prescribed WCD. The consecutive 50 patients with WCD use (median age 56 years, 38 for secondary prevention) were studied. We analyzed clinical efficacy and safety of WCD, and examined its potential roles. Of the 50 patients, 38 used WCD only during hospitalization. During WCD use [median 16 (IQR 8–33) days], all patients wore WCD for 98% of a day regardless of in or out-of-hospital use. Sustained VA was detected in 4 patients (8%; for primary prevention in 1) with 7 episodes, and 6 of 7 episodes required shock therapy. Of the 6 shock therapies, 4 were for sustained ventricular tachycardia with the median rate of 236 beats/min (IQR 203–250), and the other 2 for ventricular fibrillation. Subsequently, only 27 patients (54%) of all underwent ICD implantation following the WCD use, because of reduced risk of VA after optimal pharmacological therapy or improvement in the left ventricular function. Conclusions The WCD use for the acute phase care of patients at high risk of VA can be safe and effective, and may be useful for evaluating indication of ICD implantation.

BACKGROUNDS Postpacing interval (PPI) measured after entrainment pacing describes the distance between pacing site and reentrant circuit. However, the influential features to PPI remain to be elucidated. METHODS AND RESULTS This study included 22 cases with slow/fast atrioventricular (AV) nodal reentrant tachycardia (AVNRT), 14 orthodromic AV reciprocating tachycardia (AVRT) using an accessary pathway, 22 typical atrial flutter (AFL), and 18 other macroreentrant atrial tachycardia (atypical AFL). Rapid pacing at a pacing cycle length (PCL) 5% shorter than tachycardia cycle length (TCL) was done from a site on or close to the reentry circuit. Pacing sites included the coronary sinus ostium in AVNRT, earliest atrial activation site in AVRT, and cavotricuspid isthmus in typical AFL. In atypical AFL, tachycardia circuit was determined on the basis of CARTO mapping, and then the pacing site was. TCL was significantly longer in AVNRT and AVRT than in typical AFL and atypical AFL (both P < 0.05). PCL minus TCL value was similar among the 4 groups. PPI minus TCL value (milliseconds) was significantly longer in AVNRT (median, 40 [IQR, 29-60.8]) and AVRT (34 [20-47]) than in typical AFL (0 [0-4]) and atypical AFL (3.5 [0-8]) (both P < 0.05). Furthermore, PPI minus TCL was prolonged with shortening of PCL in AVNRT and AVRT (both P < 0.05), whereas it was unchanged in typical AFL (P = 0.50). CONCLUSION PPI after concealed entrainment is prolonged compared with TCL when the reentry circuit involves a slow conduction zone with a decremental conduction property such as the AV node.

A 73-year-old man with ischemic cardiomyopathy underwent ventricular tachycardia (VT) ablation. During right ventricular pacing, substrate mapping was performed using EnSite Precision (Abbott, St. Paul, Minnesota) with an Advisor HD Grid Mapping Catheter (Abbott). The bipolar and unipolar voltage

Most right ventricular arrhythmias (VA) originate from the outflow tract. Experiences of VA arising from the basal septum of the right ventricle (RV) are limited. We aimed to describe the ablation procedure and results, focusing on the characteristics and clinical significance of junctional rhythm (JR) appearing during radiofrequency application. Among 86 consecutive patients undergoing radiofrequency ablation for VA from the RV, 12 (14 %) (mean age, 71 ± 7 years) had their origin in the basal septum of the RV defined as the region from 1 to 5 o’clock of the tricuspid annulus (TA) in the left anterior oblique view and extending anteriorly from the TA to 2 cm. A mean QRS duration of VA was 137 ± 8 msec with normal (10/12, 83 %) or left-deviated axis (2/12, 17 %). Five patients (41 %) had structural heart diseases including three dilated cardiomyopathies. Radiofrequency energy was applied to the sites showing the earliest activation during VA and/or best pacemap. Complete elimination of VA was achieved in 11 (92 %) patients. The successful ablation site was 12 ± 4 mm away from the His-bundle electrogram recording site. Among 11 patients with successful ablation, 10 (91 %) exhibited JR (mean cycle length, 638 ± 172 ms) during ablation without subsequent atrioventricular conduction disturbance (AVCD) except for one showing high-rate JR (181 beats/min) and transient AVCD. All these patients were free from VA during 32 ± 21 months. VA originating from the basal septum of the RV can be ablated effectively. JR appears in most cases without causing AVCD, unless the rate is high.

Aims Although contact force (CF)-guided circumferential pulmonary vein isolation (CPVI) for paroxysmal atrial fibrillation (PAF) is useful, AF recurrence at long-term follow-up still remains to be resolved. The purpose of this study was to assess safety and efficacy of CF-guided CPVI and to compare residual conduction gaps during CPVI and long-term outcome between the conventional (non-CF-guided) and the CF-guided CPVI. Methods and results We studied the 50 consecutive PAF patients undergoing CPVI by a ThermoCool EZ Steer catheter (conventional group, mean age 61 ± 10 years) and the other 50 consecutive PAF patients by a ThermoCool SmartTouch catheter (CF group, 65 ± 11 years). The procedure parameters and residual conduction gaps during CPVI, and long-term outcome for 12 months were compared between the two groups. Circumferential pulmonary vein isolation was successfully accomplished without any major complications in both groups. Total procedure and total fluoroscopy times were both significantly shorter in the CF group than in the conventional group (160 ± 30 vs. 245 ± 61 min, P < 0.001, and 17 ± 8 vs. 54 ± 27 min, P < 0.001, respectively). Total number of residual conduction gaps was significantly less in the CF group than in the conventional group (2.7 ± 1.7 vs. 6.3 ± 2.7, P < 0.05). The AF recurrence-free rates after CPVI during 12-month follow-up were 96% (48/50) in the CF group and 82% (41/50) in the conventional group (P = 0.02 by log rank test). Multivariate Cox regression analysis further supported this finding. Conclusion Contact force-guided CPVI is safe and more effective in reducing not only the procedure time but also the AF recurrence than the conventional CPVI, possibly due to reduced residual conduction gaps during CPVI procedure.

Background: This study investigated the prevalence, electrocardiographic and electrophysiological characteristics, and ablation outcome of idiopathic ventricular arrhythmias (VAs) originating from the infundibular muscles (IFMs) in the right ventricle consisting of the parietal band (PB) and septal band (SB). Methods and Results: We studied 19 patients with idiopathic VA origins in the PB in 14 and SB in 5 among 294 consecutive patients with VA origins in the right ventricle. PB and SB VAs exhibited left bundle branch block with a left inferior (n=12) or superior (n=2) axis and left (n=4) or right inferior (n=1) axis pattern, respectively. In lead I, all PB VAs exhibited R waves while SB VAs often exhibited S waves. A QS pattern in lead aVR and the presence of a notch in the mid-QRS were common in all IFMs VAs. During IFMs VAs, a far-field ventricular electrogram with an early activation was always recorded in the His bundle region regardless of the location of the VA origins. With 9.2±6.9 radiofrequency applications and a duration of 972±946 seconds, catheter ablation was successful in 15 patients. VAs recurred in 4 during a follow-up period of 43±24 months. A change in the QRS morphology was observed spontaneously in 5 patients, immediately after ablation in 4, and at the time of the VA recurrence in 2. Conclusions: Idiopathic VAs originating from the IFMs are rare (PB>SB). Catheter ablation of these IFMs VAs was challenging, requiring a large amount of the radiofrequency energy delivery for a successful ablation with a relatively high recurrence rate.

Backgrounds— The parietal band is one of the muscle bands in the right ventricle. This study investigated the electrocardiographic and electrophysiological characteristics and ablation outcome of idiopathic ventricular arrhythmias (VAs) originating from the parietal band. Methods and Results— We studied 14 patients with idiopathic VA origins in the parietal band among 294 consecutive patients with VA origins in the right ventricle. The QRS morphologies of the parietal band VAs were characterized by a left bundle branch block and left inferior (n=12) or superior (n=2) axis pattern with the presence of a notch in the middle of the QRS in all cases, precordial transition at ≤lead V3 in 7 patients, and a slow QRS onset in 4 patients. During parietal band VAs, a far-field ventricular electrogram with an early activation was always recorded in the His bundle region, regardless of the location of the VA origins. During the catheter ablation, a mean number of 10.4±7.4 radiofrequency applications with a duration of 1099±1034 seconds were delivered. Catheter ablation was successful in 10 patients, and VAs recurred in 4 during a mean follow-up period of 41±24 months. A change in the QRS morphology was observed spontaneously in 4 patients, immediately after the ablation in 4, and at the time of a VA recurrence in 2. Conclusions— Idiopathic VAs rarely originated from the parietal band. The catheter ablation of the parietal band VAs was always challenging, requiring a large amount of the radiofrequency energy delivery for a successful ablation with a relatively high recurrence rate.

Contact force (CF) monitoring could be useful in accomplishing circumferential pulmonary vein (PV) isolation (CPVI) for atrial fibrillation (AF).The purpose of this study was to compare procedure parameters and outcomes between CF-guided and non-guided CPVI.Thirty-eight consecutive AF patients (mean age 60 ± 11 years, 28 paroxysmal AF) undergoing CPVI were randomized to non-CF-guided (n = 19) and CF-guided (n = 19) groups. CPVI was performed with the ThermoCool SmartTouch catheter in both groups. The end-point was bidirectional block between the left atrium (LA) and PV. In the CF group, CF was kept between 10 and 20 g during CPVI, whereas in the non-CF group, all CF information was blanked. Radiofrequency energy at 30 W in the anterior and 25 W in the posterior LA wall was applied for 20-25 seconds at each point.CPVI was successfully accomplished without any major complications in both groups. Mean CF in the non-CF and CF groups were 5.9 ± 4.5 g and 11.1 ± 4.3 g, respectively, for left-side CPVI, and 9.8 ± 6.6 g and 12.1 ± 4.8 g, respectively, for right-side CPVI (both P.001). The procedure and fluoroscopy times for CPVI in the non-CF and CF groups were 96 ± 39 minutes and 59 ± 16 minutes, respectively (P.001), and 22 ± 63 seconds and 9 ± 20 seconds (P = NS), respectively. Total number of residual conduction gaps was 6.3 ± 3.0 in the non-CF group and 2.8 ± 1.9 in the CF group (P.001). During 6-month follow-up, 84.2% of patients in the non-CF group and 94.7% in the CF group were free from any atrial tachyarrhythmias (P = .34).CF-guided CPVI is effective in reducing procedure time and additional touch-up ablation and may improve long-term outcome.

A 44-year-old man with a history of ventricular preexcitation and supraventricular tachycardia was evaluated. The baseline electrocardiogram exhibited ventricular preexcitation with a normal PR interval and a minimally negative delta wave in lead V1 and positive delta waves in the inferior leads. The administration of adenosine resulted in a progressive prolongation of the PR interval with a fixed preexcitation degree, suggesting the presence of antegrade conduction over the fasciculo-ventricular pathway. When complete right bundle branch block occurred, the degree of preexcitation never changed. These findings suggested that the fasciculo-ventricular pathway was likely to be connected to the left-sided His-Purkinje system. Keywords: Fasciculoventricular pathway, Preexcitation, Mahaim fiber, Bundle branch block

Relation of Electrogram Amplitude to Conduction VelocityBackground Low conduction velocity (CV) in the area showing low electrogram amplitude (EA) is characteristic of reentry circuit of atypical atrial flutter (AFL). The quantitative relationship between CV and EA remains unclear. We characterized AFL reentry circuit in the right atrium (RA), focusing on the relationship between local CV and bipolar EA on the circuit. Methods and Results We investigated 26 RA AFL (10 with typical AFL; 10 atypical incisional AFL; 6 atypical nonincisional AFL) using CARTO system. By referring to isochronal and propagation maps delineated during AFL, points activated faster on the circuit were selected (median, 7 per circuit). At the 196 selected points obtained from all patients, local CV measured between the adjacent points and bipolar EA were analyzed. There was a highly significant correlation between local CV and natural logarithm of EA (lnEA) (R2 = 0.809, P < 0.001). Among 26 AFL, linear regression analysis of mean CV, calculated by dividing circuit length (152.3 ± 41.7 mm) by tachycardia cycle length (TCL) (median 246 msec), and mean lnEA, calculated by dividing area under curve of lnEA during one tachycardia cycle by TCL, showed y = 0.695 + 0.191x (where: y = mean CV, x = lnEA; R2 = 0.993, P < 0.001). Local CV estimated from EA with the use of this formula showed a highly significant linear correlation with that measured by the map (R2 = 0.809, P < 0.001). Conclusion The lnEA and estimated local CV show a highly positive linear correlation. CV is possibly estimated by EA measured by CARTO mapping.

CartoSound Merge Using Left Atrial Posterior Wall Background CartoSound™ (CS) module is useful in integrating 3-dimensional (3D) left atrial (LA) image with CT image. Integration method, however, has not been established. We reported the accuracy of LA electroanatomical (EA) and CT image integration by registering LA roof (LAR) and posterior wall (LAPW). Methods The consecutive 56 atrial fibrillation patients undergoing pulmonary vein isolation were studied. In the initial 29 patients, before the transseptal puncture, 3D CS LAR and LAPW image was created by registering a mean of 10 contour lines between the right and left pulmonary veins. After transseptally inserting a mapping catheter into LA, 3D EA image of LAR and LAPW was obtained by sampling a mean of 40 points. LA CT image was taken at the full-inspiratory position and 0% of R–R interval. After visual alignment of CS or EA and LA CT image, the 2 images were integrated with surface registration program. In the latter 27 patients, both CT and CS images were taken while matching the respiratory phase at the end-tidal position and cardiac cycle at 50% of R–R interval. Results In the initial 29 patients, the mean distances between EA and CT images and between CS and CT images were 1.53 ± 0.27 and 1.59 ± 0.23 mm, respectively (P = NS). In the latter 27, the mean distance was decreased to 1.08 ± 0.14 mm (P