Vein of Marshall chemical ablation decreases atrial fibrillation drivers detected by CARTOFINDER.

INTRODUCTION: This study sought to elucidate the impact of vein of Marshall (VOM) chemical ablation on atrial fibrillation (AF) drivers by investigating the changes in CARTOFINDER mappings before and after VOM chemical ablation in patients with persistent AF. METHODS: This study included 23 consecutive patients undergoing catheter ablation for long-persistent AF (>18 months). VOM chemical ablation was performed following pulmonary vein isolation. CARTOFINDER and AF cycle length (AFCL) maps were created in the left atrium (LA) before and after VOM chemical ablation. The LA was divided into 8 segments, and the number of focal activation points with 6 or more repetitions was counted in each segment. RESULTS: The number of focal activation points was largest in the LA appendage (LAA). After VOM chemical ablation, the number of focal activation points in the LA decreased significantly (37 [interquartile range, IQR: 19-55] vs. 15 [IQR: 7-21], p < .001), and median AFCL was significantly prolonged (159 [147-168] vs. 164 [150-173] ms, p < .001). In the assessment of each segment, significant decreases in focal activation points were observed in the inferior, lateral, and anterior segments and LAA. Among the focal activation points disappearing after chemical ablation, the number in the non-ethanol-affected area was significantly larger than that in the affected area (13 [8-25] vs. 4 [1-10], p < .001). CONCLUSIONS: VOM chemical ablation decreases AF drivers detected by CARTOFINDER. Mechanisms other than direct myocardial damage are considered to contribute the attenuation of AF drivers.

Delivery catheter system carries more physiological right ventricular septal pacing than stylet system.

INTRODUCTION: The Mt. FUJI multicenter trial demonstrated that a delivery catheter system had a higher rate of successful right ventricular (RV) lead deployment on the RV septum (RVS) than a conventional stylet system. In this subanalysis of the Mt. FUJI trial, we assessed the differences in electrocardiogram (ECG) parameters during RV pacing between a delivery catheter system and a stylet system and their associations with the lead tip positions. METHODS: Among 70 patients enrolled in the Mt FUJI trial, ECG parameters, RV lead tip positions, and lead depth inside the septum assessed by computed tomography were compared between the catheter group (n = 36) and stylet group (n = 34). RESULTS: The paced QRS duration (QRS-d), corrected paced QT (QTc), and JT interval (JTc) were significantly shorter in the catheter group than in the stylet group (QRS-d: 130 ± 19 vs. 142 ± 15 ms, p = .004; QTc: 476 ± 25 vs. 514 ± 20 ms, p < .001; JTc: 347 ± 24 vs. 372 ± 17 ms, p < .001). This superiority of the catheter group was maintained in a subgroup analysis of patients with an RV lead tip position at the septum. The lead depth inside the septum was greater in the catheter group than in the stylet group, and there was a significant negative correlation between the paced QRS-d and the lead depth. CONCLUSION: Using a delivery catheter system carries more physiological depolarization and repolarization during RVS pacing and deeper screw penetration in the septum in comparison to conventional stylet system. The lead depth could have a more impact on the ECG parameters rather than the type of pacing lead.

Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias.

INTRODUCTION: Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. METHODS: This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. RESULTS: Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. CONCLUSION: A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Impact of Interatrial Epicardial Connections on the Dominant Frequency of Atrial Fibrillation.

BACKGROUND: An epicardial connection (EC) between the right-sided pulmonary venous (RtPV) carina and right atrium (RA) may preclude PV isolation, but its electrophysiological role during atrial fibrillation (AF) remains unknown.Methods and Results: This prospective observational study included 98 consecutive patients undergoing catheter ablation for AF, subdivided into the EC group (n=17) and non-EC group (n=80) based on observation of RA posterior wall breakthrough during RtPV pacing. Mean left atrial (LA) dominant frequency (mean DFLA) was defined as the averaged DFs at the right and left PVs and LA appendage. The regional DF was higher in the EC group vs. the non-EC group except at the left PV antrum. The DF at the RA appendage (RAA) and mean DFLAwere equivocal (6.5±0.7 vs. 6.6±0.7 Hz) in the EC group, but the mean DFLAwas significantly higher than that at the RAA (5.8±0.6 vs. 6.1±0.5 Hz, P=0.001) in the non-EC group, suggesting an LA-to-RA DF gradient. A significant correlation of DF between the RtPV antrum and RAA was observed in the EC group (P<0.001, r=0.84) but not in the non-EC group. CONCLUSIONS: An electrophysiological link via interatrial ECs might attenuate the hierarchical nature of activation frequencies of AF, leading to advanced electrical remodeling of the atria.

Inter-atrial epicardial muscular fibers as a possible source of atrial tachyarrhythmias.

A 22-year-old woman without structural heart disease underwent catheter ablation of frequent premature atrial contractions (PACs). Radiofrequency applications from both the right and left atrium were effective in suppressing or eliminating these PACs. The distance between the right atrial ablation site and the successful ablation site at the right-sided pulmonary venous carina measured 18 mm on the CARTO map, and no cardiac structure, i.e. the inter-atrial septum, was present between those sites. Taken together, the epicardial muscular fibers in the inter-atrial groove were considered to play a role as an arrhythmogenic source of this atrial tachyarrhythmia. Learning objective: Epicardial muscular fibers connecting the right atrium and right-sided pulmonary venous carina are known to preclude isolation of the veins. This epicardial connection in the interatrial groove can be an arrhythmogenic source or part of a reentrant circuit of atrial tachyarrhythmias.

Impact of catheter ablation and subsequent recurrence of atrial fibrillation on glucose status in patients undergoing continuous glucose monitoring.

Although glucose metabolism and atrial fibrillation (AF) have complex interrelationships, the impact of catheter ablation of AF on glucose status has not been well evaluated. Continuous glucose monitoring (CGM) with a FreeStyle Libre Pro (Abbott) was performed for 48 h pre-procedure, during the procedure, and for 72 h post-procedure in 58 non-diabetes mellitus (DM) patients with symptomatic AF and 20 patients with supraventricular or ventricular arrhythmias as a control group. All ablation procedures including pulmonary vein isolation were performed successfully. Glucose levels during procedures consistently increased in the AF and control groups (83.1 ± 16.1 to 110.0 ± 20.5 mg/dL and 83.3 ± 14.7 to 98.6 ± 16.3 mg/dL, respectively, P < 0.001 for both), and Δ glucose levels (max minus min/procedure) were greater in the AF group than control group (P < 0.001). There was a trend toward higher mean glucose levels at 72 h after the procedures compared with those before the procedures in both the AF and control groups (from 103.4 ± 15.6 to 106.1 ± 13.0 mg/dL, P = 0.063 and from 100.2 ± 17.1 to 102.9 ± 16.9 mg/dL, P = 0.052). An acute increase in glucose level at the time of early AF recurrence (N = 9, 15.5%) could be detected by simultaneous CGM and ECG monitoring (89.7 ± 18.0 to 108.3 ± 30.5 mg/dL, P = 0.001). In conclusion, although AF ablation caused a statistically significant increase in the glucose levels during the procedures, it did not result in a pathologically significant change after ablation in non-DM patients. Simultaneous post-procedure CGM and ECG monitoring alerted us to possible acute increases in glucose levels at the onset of AF recurrence.

Usefulness of delivery catheter on accurate right ventricular septal pacing: Mt FUJI trial.

AIMS: Although the delivery catheter system for pacemaker-lead implantation is a new alternative to the stylet system, no randomized controlled trial has addressed the difference in right ventricular (RV) lead placement accuracy to the septum between the stylet and the delivery catheter systems. This multicentre prospective randomized controlled trial aimed to prove the efficacy of the delivery catheter system for accurate delivery of RV lead to the septum. METHODS AND RESULTS: In this trial, 70 patients (mean age 78 ± 11 years; 30 men) with pacemaker indications of atrioventricular block were randomized to the delivery catheter or the stylet groups. Right ventricular lead tip positions were assessed using cardiac computed tomography within 4 weeks of pacemaker implantation. Lead tip positions were classified into RV septum, anterior/posterior edge of the RV septal wall, and RV free wall. The primary endpoint was the success rate of RV lead tip placement to the RV septum. RESULTS: Right ventricular leads were implanted as per allocation in all patients. The delivery catheter group had higher success rate of RV lead deployment to the septum (78 vs. 50%; P = 0.024) and narrower paced QRS width (130 ± 19 vs. 142 ± 15 ms P = 0.004) than those in the stylet group. However, there was no significant difference in procedure time [91 (IQR 68-119) vs. 85 (59-118) min; P = 0.488] or the incidence of RV lead dislodgment (0 vs. 3%; P = 0.486). CONCLUSION: The delivery catheter system can achieve a higher success rate of RV lead placement to the RV septum and narrower paced QRS width than the stylet system. TRIAL REGISTRATION NUMBER: jRCTs042200014 (https://jrct.niph.go.jp/en-latest-detail/jRCTs042200014).

Conversion to partial isthmus-dependent flutter during cavotricuspid isthmus ablation: The utility of Advisor HD grid in identifying local fragment electrograms.

Complete block creation by radiofrequency (RF) ablation at the cavotricuspid isthmus (CTI) is a highly successful procedure for the treatment of typical atrial flutter (AFL). Occasionally, a rare type of AFL, such as lower or upper loop reentry, or partial isthmus-dependent flutter, can coexist with typical right AFL. A 73-year-old man underwent CTI ablation for a clockwise CTI-dependent typical atrial flutter. During the ablation procedure, the morphology of the flutter wave changed in the surface electrocardiogram and endocardial atrial activation sequence, suggesting that the typical AFL had converted to another AFL (AFL2). High-density mapping using the HD grid catheter could not reveal the reentrant circuit of AFL2 but detected a critical conduction gap at the boundary between the inferior vena cava and CTI. There was also an impulse collision in the remaining CTI. The RF application at the gap terminated the AFL2 and completed the block line of the CTI. Based on these findings, AFL2 was comparable with partial isthmus-dependent flutter. The present case demonstrates the utility of high-density mapping with a HD grid for the identification of small amplitude high-frequency electrograms at critical sites of the arrhythmia. Learning objective: A rare type of atrial flutter (AFL) can coexist with typical AFL. In such cases, a high-density mapping is useful to identify the critical portion of the reentrant circuit. The Advisor HD grid multipolar catheter (Abbott, St Paul, MN, USA) is unique in that it allows bipolar recording perpendicular and parallel to the splines via 16 electrodes. In this case report, high density mapping using HD grid catheter identified small amplitude high-frequency electrograms at critical sites of the arrhythmia.

An Epicardial Connection With a Unidirectional Conduction Property From the Left Atrium to Pulmonary Vein.

The presence of an epicardial connection between the left-sided pulmonary vein and left atrium was suggested during catheter ablation of atrial fibrillation because of sustainable unidirectional entrance conduction after complete endocardial ablation, centrifugal breakout deep inside the pulmonary vein, and immediate elimination of the conduction by point ablation. (Level of Difficulty: Advanced.).

Epicardial Connections as Intra-Atrial Conduction Routes in a Patient With Advanced Atrial Remodeling.

In a patient with long-standing persistent atrial fibrillation, elimination of an epicardial connection between the right-sided pulmonary venous carina and the right atrium during catheter ablation resulted in intra-atrial conduction injuries in the presence of advanced atrial remodeling. (Level of Difficulty: Advanced.).

Reverse-Type Left Posterior Fascicular Ventricular Tachycardia: A New Electrocardiographic Entity.

OBJECTIVES: This study sought to demonstrate a new type of verapamil-sensitive fascicular ventricular tachycardia (VT) with a reverse circuit. BACKGROUND: Left posterior fascicular ventricular tachycardia (LPFVT) is the most common form of verapamil-sensitive fascicular VT. Reverse-type LPFVT has not been reported. METHODS: We searched for a reverse-type LPFVT among 242 patients with verapamil-sensitive VT from February 2006 to September 2019. RESULTS: Three patients had a reverse-type LPFVT (cycle lengths: 340, 360, and 340 ms). QRS configuration during VT was narrow (140, 150, and 140 ms) and exhibited rSr' morphology in V1 with an early precordial transition and inferior axis. Two of 3 patients had common-type LPFVT. During reverse-type LPFVT, the earliest ventricular activation was the left superior middle septum. Fragmented Purkinje potentials (P1) buried within the local ventricular electrogram were recorded with an activation sequence from the apex to the base and were linked to the subsequent left ventricular septal activation. After radiofrequency catheter ablation at P1 during LPFVT, the reverse-type LPFVT also became noninducible. In 1 patient with only the reverse-type LPFVT, radiofrequency catheter ablation at the earliest LV activation site suppressed VT. These findings suggest that this new type of verapamil-sensitive fascicular VT shares a re-entrant circuit with a reverse direction of common LPFVT with an intramural exit site at the superior middle septum. CONCLUSIONS: Reverse-type LPFVT can occur. If common LPFVT exists, diastolic P1 during LPFVT can be a common target of ablation. If only reverse-LPFVT is inducible, the earliest ventricular activation site can be a target.

A simple pacing maneuver to unmask an epicardial connection involving the right-sided pulmonary veins.

INTRODUCTION: An epicardial connection (EC) between the right-sided pulmonary venous (PV) carina and right atrium (RA) is one of the mechanisms for which carinal ablation is required for right-sided PV isolation. The purpose of the study was to devise a simple pacing maneuver to differentiate an EC from a residual conduction gap on the antral ablation line during radiofrequency catheter ablation. METHODS AND RESULTS: This study included 133 consecutive patients. After one round of ablation, electrograms at the posterior antrum outside the ablation line were recorded during sinus rhythm (SR) and coronary sinus (CS) pacing, and intervals between the antral and PV potentials were measured in each rhythm. The ΔintervalSR-CS was calculated as the difference between the interval during SR and that during CS pacing. Presence of an EC was confirmed by observation of a RA posterior wall breakthrough during right-sided PV pacing, which was then targeted for ablation. Patients with nonachievement of first-pass isolation (N = 35) and with PV reconnection during the procedure (N = 9) were classified into the EC-group (N = 20) and gap-group (N=24), respectively. The prevalence of carina breakthrough during SR was higher in the EC-group than the gap-group (18 [95%] vs. 1 [4%] patients, p < .0001). The ΔintervalSR-CS was larger in the EC-group versus gap-group (71 [interquartile range, 57-97] vs. 6 [2-9] ms, p < .0001). In all patients with an EC, RA ablation resulted in delay (32 [20-40] ms) (N = 15) or elimination of PV potentials (N = 5). CONCLUSION: An EC can be efficiently discriminated from a conduction gap by a simple pacing maneuver.

Predictors of Recurrence after Catheter Ablation of Paroxysmal Atrial Fibrillation in Different Follow-Up Periods.

Background and objectives: Pulmonary vein (PV) reconnection is a major reason for recurrence after catheter ablation of paroxysmal atrial fibrillation (PAF). However, the timing of the recurrence varies between patients, and recurrence >1 year after ablation is not uncommon. We sought to elucidate the characteristics of atrial fibrillation (AF) that recurred in different follow-up periods. Materials and Methods: Study subjects comprised 151 consecutive patients undergoing initial catheter ablation of PAF. Left atrial volume index (LAVi) and atrial/brain natriuretic peptide (ANP/BNP) levels were systematically measured annually over 3 years until AF recurred. Results: Study subjects were classified into four groups: non-recurrence group (n = 84), and short-term- (within 1 year) (n = 30), mid-term- (1-3 years) (n = 26), and long-term-recurrence group (>3 years) (n = 11). The short-term-recurrence group was characterized by a higher prevalence of diabetes mellitus (hazard ratio 2.639 (95% confidence interval, 1.174-5.932), p = 0.019 by the Cox method), frequent AF episodes (≥1/week) before ablation (4.038 (1.545-10.557), p = 0.004), and higher BNP level at baseline (per 10 pg/mL) (1.054 (1.029-1.081), p < 0.0001). The mid-term-recurrence group was associated with higher BNP level (1.163 (1.070-1.265), p = 0.0004), larger LAVi (mL/m2) (1.033 (1.007-1.060), p = 0.013), and longer AF cycle length at baseline (per 10 ms) (1.194 (1.058-1.348), p = 0.004). In the long-term-recurrence group, the ANP and BNP levels were low throughout follow-up, as with those in the non-recurrence group, and AF cycle length was shorter (0.694 (0.522-0.924), p = 0.012) than those in the other recurrence groups. Conclusions: Distinct characteristics of AF were found according to the time to first recurrence after PAF ablation. The presence of secondary factors beyond PV reconnections could be considered as mechanisms for the recurrence of PAF in each follow-up period.