BACKGROUND AND AIMS:Posterior papillary muscle (PPM) and false tendons (FTs) in the right ventricle (RV) may act as a potential source of ventricular arrhythmias(VAs). We aimed to systematically describe the electrophysiological characteristics and the outcome of radiofrequency catheter ablation (RFCA) of VAs originating from the RV PPM -FT complex. METHODS:From a total of 2184 patients with VAs who underwent catheter ablation, 12 patients (0.55%) with VAs associated with RV PPM-FTs complex were enrolled in the study. Activation mapping and pace mapping were performed to localize the origin of VAs. Intracardiac echocardiography (ICE) was used in all patients to directly visualize the PPM and the FTs. We chose 12 patients with VAs originating from the RV moderate band (MB) as the control group. CONCLUSIONS:In contrast to the MB group, the QRS duration, the R wave duration and the RS interval of lead V1 of the study group was longer. The negative component in inferior leads (II, III, aVF) of the study group was deeper than the MB group. The PVCs in the study group were successfully eliminated by ablation in all patients. The target sites were confirmed to be related to the RV PPM and FTs complex. A pre-systolic potential was observed preceding local ventricular activation in seven patients.

BACKGROUND:Previous studies have demonstrated electrical connections between ipsilateral pulmonary veins (PVs). This study aimed to characterize the electrophysiological features of right middle pulmonary vein (RMPV) originating from right superior pulmonary vein (RSPV). METHODS:We prospectively enrolled patients with atrial fibrillation (AF) with an identifiable RMPV on pre-procedural cardiac computed tomography angiography (CTA) and in whom a multipolar mapping catheter could be advanced into the RMPV. Cardiac CTA was used to assess left atrial and PV anatomy, including ostial diameter, area and ovality index. The RMPV was defined as an inferiorly directed branch arising from the ostium-proximal segment of the RSPV, within 1 cm from the ostium RESULTS: A total of 118 patients were included (mean age 63.9 years, 63.6% male). The mean RMPV ostial area was 0.69 ± 0.41 cm2, with maximum and minimum diameters of 0.83 ± 0.21 cm and 0.63 ± 0.17 cm, respectively. The mean ovality index was 1.35 ± 0.27 for RMPV. AF triggers originating from the RMPV were identified in 3 patients (2.5%). During circumferential pulmonary vein isolation (CPVI), RMPV potentials were eliminated in 99 patients (83.9%), concurrently with disappearance of RSPV potentials. In the remaining 19 patients, RMPV potentials persisted after CPVI and required additional carina ablation to achieve isolation. After a mean follow-up of 41 months, 96 patients remained free from atrial tachyarrhythmia recurrence after the index procedure. CONCLUSIONS:RMPV potentials predominantly originate from the RSPV and can usually be eliminated during CPVI. However, additional carina ablation is required in a subset of patients to achieve RMPV isolation.

BACKGROUND:Bundle branch reentry ventricular tachycardia (BBRT) in patients without structural heart disease (SHD) has been well-documented. However, the occurrence of concomitant atrial tachycardia (AT) in this cohort remain poorly characterized. The study aimed to investigate the prevalence, clinical characteristics, and electrophysiological properties of concomitant AT in patients with BBRT. METHODS:Eighteen patients without SHD were enrolled. Detailed electrophysiological studies were performed to identify and characterize concomitant ATs. Catheter ablation was performed for both BBRT and atrial ATs. RESULTS:Among 18 patients with BBRT, 6 patients (33.3%; mean age 26.3 years) presented with a total of 7 ATs. Three patients had a history of AT ablation, two exhibited BBRT concomitant with AT during the index procedure, and two developed AT following BBRT ablation. All ATs originated from the right atrium, with the following distribution: coronary sinus ostium (CSO) (n = 4), typical atrial flutter (AFL) (n = 2) and mid-crista terminalis (MCT) (n = 1). The mean tachycardia cycle length (TCL) was 337±61 ms. Acute procedural success was achieved in all cases. During a mean follow-up of 54.1±26.0 months, all patients remained free from AT and BBRT recurrence. However, progressive deterioration of left ventricular function requiring cardiac resynchronization therapy occurred in one patient, and two patients developed ventricular enlargement. CONCLUSIONS:Concomitant AT was observed in one-third of patients with BBRT without SHD. Catheter ablation proved effective in treating both arrhythmias. Intensive long-term monitoring of cardiac function is recommended in this population.

Atrial fibrillation (AF) is the most common atrial arrhythmia with high prevalence, low awareness, and low treatment rate in China. Catheter ablation (CA) is an effective treatment, but recurrence remains common in persistent AF (PsAF). The present study aimed to develop a tool for 1-year atrial tachyarrhythmia (ATa) recurrence risk stratification after de novo CA. This multicenter, retrospective study collected data from four Chinese hospitals between January 2015 and May 2021. Eligible patients were randomly divided in a 2:1 ratio to development (DC) and test cohorts (TC). One-year ATa recurrence status was primarily obtained from existing medical records. Candidate risk factors for recurrence were initially identified through literature review and investigator consensus. Univariable and multivariable Cox regression analyses were performed to develop the model. The model’s discrimination and calibration were evaluated in both cohorts to assess performance. A total of 1,689 patients who underwent de novo CA were included, with 1,126 in DC and 563 in TC. The mean age was 60.5 years, 71.9

INTRODUCTION:Prolonged sinus pause (PSP) after atrial fibrillation (AF) termination shortly after catheter ablation seems to be a reversible phenomenon without further need for pacemaker implantation (PMI). However, no mature management strategy has been established. METHODS:In this prospective observational study, we included consecutive patients who developed PSP ≥ 3 s upon AF termination during hospitalization following AF ablation at our center between October 2020 and October 2022. Regular follow-up was conducted. RESULTS:Twelve patients (mean age 66.3 ± 8.5 years; 7 females) were included. PSP ≥ 3 s upon AF termination initiated at a median of 2.0 days (IQR: 1.3-3.8) post-ablation and resolved by 5.0 days (IQR: 3.5-7.5). Three patients received temporary PMI, all of which were removed before discharge without further pacing. One patient underwent permanent PMI during hospitalization due to Adams-Stokes syndrome. After discharge, one patient received permanent pacing for symptomatic sinus arrest at 3 months, and another underwent atrioventricular node ablation followed by permanent pacing due to recurrent arrhythmia. The remaining patients had no related symptoms or need for pacing during follow-up. CONCLUSION:PSP ≥ 3 s upon AF termination shortly after catheter ablation appears to be reversible. A watch-and-wait strategy was practical. Management may involve discontinuation of antiarrhythmic drugs or temporary pacing support. A small proportion of patients may ultimately require permanent PMI.

BACKGROUND:Atrial substrate progression is common among patients with atrial fibrillation (AF). Unipolar voltage mapping more comprehensively characterizes the atrial substrate compared with bipolar mapping. OBJECTIVE:This study aimed to characterize atrial substrate progression in patients with recurrent AF using unipolar mapping after pulmonary vein isolation. METHODS:In this single-center retrospective study, consecutive AF patients undergoing index and redo ablations were enrolled. Electroanatomic maps from both ablations were compared and assessed by unipolar and bipolar voltage. Low-voltage zone (LVZ) was defined as bipolar voltage <0.5 mV or unipolar voltage <1.6 mV. Patients were categorized into progression (n = 35) and nonprogression (n = 15) groups. RESULTS:A total of 50 patients (mean age 59.5 ± 12.6 years; 40 males) were enrolled. Compared with index ablation, redo ablation demonstrated significantly larger bipolar LVZ (Bi-LVZ) total area (21.25 vs. 15.86 cm2, p = 0.007) and LVZ burden (0.20 vs. 0.14, p = 0.002). The progression group showed a higher LVZ burden (unipolar: 0.27 vs. 0.12, p = 0.007; bipolar: 0.16 vs. 0.09, p = 0.019) and a greater ratio of total unipolar to bipolar LVZ area (Uni/Bi) (1.75 vs. 1.34, p = 0.042) during index ablation compared with the nonprogression group. Linear regression revealed a positive correlation between index-ablation Uni/Bi ratio and the degree of Bi-LVZ area expansion at redo ablation (β = 7.20, p < 0.001). CONCLUSION:Uni-LVZ characterizes the atrial substrate progression, with the higher Uni/Bi ratio during index ablation indicates greater Bi-LVZ expansion at redo ablation.

BACKGROUND:Cryoballoon ablation (CBA) has been shown as an effective alternative strategy to radiofrequency ablation (RFA) for the treatment of paroxysmal atrial fibrillation (PAF), with comparable efficacy and safety. However, the electrophysiological properties in pulmonary veins (PVs) after CBA and RFA are not well understood. This study compares these characteristics in PAF patients. METHODS:Consecutive patients with PAF undergoing initial catheter ablation were prospectively randomized to CBA (N = 50) or RFA (N = 50) for PV isolation (PVI). Each PV's automaticity and excitability were assessed. Follow-up for atrial tachyarrhythmia recurrence at 3, 6, and 12 months was monitored via electrocardiogram/Holter. RESULTS:A total of 100 patients were randomized (mean age of 62 ± 10 years). After initial PVI, 33 (66%) patients in the RFA group retained PV automaticity, compared to 17 (34%) patients in the CBA group (p = 0.027). The number of PVs exhibiting stable automaticity was significantly higher in the RFA group compared with the CBA group (51/198 vs. 19/197, p < 0.0001). Ipsilateral PV crosstalk was more common in the RFA group (7/17 vs. 0/2, p = 0.5088). Moreover, low-frequency pacing revealed local capture in 46% of the RFA group versus 2% of the CBA group (p < 0.0001). Fluoroscopy time was shorter with RFA (p = 0.0003), but ablation time was longer (p < 0.0001). Over an average of 13-month follow-up, atrial tachyarrhythmia recurrence rates were similar between groups. CONCLUSIONS:Automaticity and excitability within PVs were more prevalent in the RFA group than the CBA group after AF ablation.

Background Ventricular tachycardia (VT) storm is a life-threatening arrhythmic emergency. In recent years, autonomic neuromodulation has emerged as an adjunctive strategy beyond catheter ablation, antiarrhythmic drugs, and sedation. Case Summary A 39-year-old man with dilated cardiomyopathy and recurrent VT storm despite implantable cardioverter-defibrillator implantation, multiple ablation procedures, and long-term amiodarone therapy was admitted with incessant VT. Combined endocardial-epicardial ablation failed to provide durable control. Refractory VT recurred postprocedure and was suppressed under deep sedation but recurred upon sedation weaning. Sequential left stellate ganglion blockage (LSGB) and bilateral thoracoscopic cardiac sympathetic denervation (CSD) successfully terminated the storm, providing arrhythmia-free survival for 1 year until recurrence, after which he ultimately underwent orthotopic heart transplantation. Discussion This case highlights the efficacy of CSD as a rescue therapy in refractory VT storm associated with structural heart disease. Suppression of VT using LSGB may predict a favorable response to CSD. Take-Home Messages Autonomic neuromodulation, including CSD, is an adjunctive therapeutic approach for VT storm, offering sustained sympathetic suppression and VT control. Patients who demonstrate good VT suppression with LSGB, suggesting a predominant sympathetic contribution, may be favorable candidates for CSD.

BACKGROUND AND AIMS:The optimal long-term antithrombotic strategy after left atrial appendage occlusion (LAAO) remains undetermined. The present study aimed to investigate whether half-dose rivaroxaban (10 mg daily) could better reduce silent cerebral embolic lesions (SCEs) and preserve cognitive function compared to antiplatelet therapy after successful LAAO. METHODS:In this investigator-initiated, prospective, multicenter, randomized controlled trial, patients with successful LAAO confirmed 45 days post-procedure were assigned 1:1 to half-dose rivaroxaban or antiplatelet therapy group. Diffusion-weighted magnetic resonance imaging and cognitive assessments were repeated at 90, 180 and 365 days after LAAO. The primary outcome was the patient-level incidence of any newly detected SCE during follow-up. Secondary outcomes included cognitive trajectories, SCE burden, and a composite of all-cause mortality, clinical thromboembolic events and major bleeding. RESULTS:Between December 2022 and February 2025, 164 patients were randomized. The patient-level incidence of new SCEs was significantly lower in the half-dose rivaroxaban group than in the antiplatelet therapy group (10/82 [12.2%] vs. 26/82 [31.7%]; P = 0.005). At 365 days, model-derived between-group differences favored the half-dose rivaroxaban group for both Mini-Mental State Examination (2.56; 95% confidence interval [CI] 1.11-4.01; P < 0.001) and Montreal Cognitive Assessment (2.67; 95% CI 1.07-4.26; P = 0.001) scores. The composite clinical outcome occurred in 2.4% of the half-dose rivaroxaban group vs. 11.0% of the antiplatelet therapy group (P = 0.057). CONCLUSIONS:In patients eligible for oral anticoagulation after successful LAAO, rivaroxaban 10 mg daily significantly reduced SCEs and better maintained cognitive function compared with antiplatelet therapy, with numerically fewer composite clinical events.

ABSTRACT Background Discrete prepotentials (DPPs) mapped inside aortic sinuses of Valsalva (ASVs) are deemed as reliable targets for ablation of premature ventricular contractions (PVCs). Nevertheless, ablation may still fail, necessitating further investigation. This study aimed to investigate the electrophysiological features and ablation approaches for PVCs with failed ablation inside ASVs, despite identified DPPs. Methods and Results Patients undergoing PVCs ablation requiring left ventricular outflow tract mapping were consecutively enrolled at six centers. Inclusion criteria comprised the presence of reproducible DPPs in ASVs and the earliest activation inside ASVs preceding the left ventricle. Patients were divided into ASV and non‐ASV groups based on ablation outcomes within ASVs. Of 780 assessed patients, 40 (age 47.5 ± 19.4; 17 males) were included in the final analysis, with 10 in the non‐ASV group. The interval from DPPs to QRS onset (DPP‐QRS) in the ASV group significantly exceeded that in the non‐ASV group (44.3 ± 6.7 ms vs. 15.0 ± 5.0 ms, p < 0.001). A DPP‐QRS interval < 25 ms perfectly differentiated non‐ASV from ASV cases. Successful ablation beneath ASVs was achieved in all non‐ASV patients, despite the local potential preceding the QRS onset by only 2.3 ± 8.0 ms. In the non‐ASV group, the distance between locations of targets and DPPs was 13.3 ± 4.2 mm, negatively correlated with the DPP‐QRS interval ( R 2 = 0.618, p = 0.007). Over a 22‐month follow‐up, one patient in the non‐ASV group had recurrence. Conclusion DPPs mapped inside ASVs, despite being the earliest sites, do not necessarily represent PVCs targets. An infra‐valvular approach is suggested with a DPP‐QRS interval < 25 ms.

BACKGROUND:The occurrence of a left free-wall (LFW) accessory pathway (AP) with concentric activation sequences in the coronary sinus (CS) during orthodromic atrioventricular reentrant tachycardia (OAVRT) is an uncommon phenomenon. METHODS:Using three-dimensional (3D) mapping system in eight patients with LFW-AP (mean age 44±9.9 years), we systematically analyzed mitral annular (MA) activation during OAVRT. RESULTS:The primary location of the APs was in the left lateral region in seven patients. The tachycardia, characterized by varying CS sequences, remained sustainable in three patients and was inducible in four patients following the initial ablation at the earliest retrograde atrial insertions. The tachycardia cycle length (TCL) was comparable to the baseline TCL (345.4±94.2  vs. 345.6±93.4 ms; p = 0.99). Moreover, the tachycardia was terminated by ablating the earliest retrograde atrial activation region adjacent to the initial ablation site. One patient with a history of left lateral AP ablation exhibited mitral isthmus (MI) block, and the left anterior AP was successfully ablated. Following a mean follow-up of 50.5 months, no recurrence of tachycardia was reported by any patient. CONCLUSION:LFW-AP with concentric CS activation sequences represents a distinctive electrophysiological entity, our study demonstrates detailed mapping in the vicinity of the MA is imperative to localize the secondary atrial insertion site of the AP or to identify multiple APs in close proximity to the initial ablation site. CLINICAL TRIAL REGISTRATION:This retrospective study does not require clinical trial registration.

BACKGROUND:Pre-implantation screening is a crucial step in preventing inappropriate sensing in patients with subcutaneous implantable cardioverter defibrillators (S-ICDs). Paced QRS-T morphology may influence screening outcomes. We aimed to explore the impact of pacing rhythm and different pacing sites on pre-implantation screening of S-ICD. METHODS AND RESULTS:This prospective, single-center study enrolled patients referred for radiofrequency ablation, with both left and right-heart access. A contact-force ablation catheter was used to mimic ventricular pacing at different sites. Automatic screening tests for S-ICD eligibility were performed during pacing and sinus rhythm. The impact of pacing sites on S-ICD eligibility was assessed. Thirty patients (age 54.0 ± 15.0 years, 73.3% male) were enrolled. The overall passing rate during intrinsic sinus rhythm was 86.7%. Compared with sinus rhythm, conduction system pacing from His bundle or left bundle branch demonstrated comparable pass rates and the number of passed vectors, whereas right ventricular septum (RVS) pacing exhibited significantly lower pass rates and less pass vectors. Among all RVS pacing sites, the lowest pass rate was observed at the apical portion, followed by middle and basal portion (p < 0.001 for all comparisons). CONCLUSION:Conduction system pacing preserves patient eligibility for S-ICD comparable to sinus rhythm, while RVS pacing significantly impairs sensing performance, with the greatest deterioration observed in apical pacing. These findings underscore the advantages of conduction system pacing in optimizing sensing function for patients eligible for both S-ICDs and pacemakers.

BACKGROUND:Pulsed-field ablation (PFA) emerges as an innovative nonthermal energy modality for catheter ablation of atrial fibrillation (AF). This study aimed to assess the safety and effectiveness of a novel PFA system that uses a multichannel, circular ablation catheter with adjustable diameters in treating paroxysmal AF. METHODS:This clinical trial (PF-Beat-AF) was a prospective, multicenter, single-arm study. Patients with paroxysmal AF underwent pulmonary vein isolation (PVI) using the PFA system, and were followed at discharge, 7-day, 1-, 3-, 6- and 12-month post-procedure. Primary safety endpoint was the incidence of primary adverse events (PAEs). While primary effectiveness endpoint was freedom from documented atrial arrhythmia recurrence lasting >30 s during the 3-12 months evaluation period. RESULTS:A total of 161 patients were enrolled and 159 patients were treated in eight centers. Conscious sedation was used in 68.6 % of cases, and 40.9 % of procedures were completed without fluoroscopy. The mean total procedure time was 132.3 ± 40.4 min, and fluoroscopy time averaged 6.4 ± 6.8 min. Acute PVI was achieved in 100 % of patients. One PAE (0.6 %) occurred (pericardial tamponade, resolved). At 12 months, 87.7 % (95 % CI: 82.5 %-92.9 %) of patients remained free from atrial arrhythmia after the blanking period. No significant differences in effectiveness were observed between conscious sedation and general anesthesia/deep sedation, or fluoroscopy and zero-fluoroscopy cases. CONCLUSION:The results of clinical trial demonstrated the safety and effectiveness of the PFA system in treating paroxysmal AF, including successful use with conscious sedation and zero-fluoroscopy.

Background Left atrial appendage occlusion (LAAO) was associated with a high incidence of procedure‐related silent cerebral embolism (SCE). There are limited data regarding the long‐term cognitive trajectory of patients undergoing LAAO. The aim of our study was to comprehensively assess the acute and long‐term impact of SCE during and after LAAO. Methods Consecutive patients with atrial fibrillation referred for LAAO from the First Affiliated Hospital with Nanjing Medical University between February 2021 and February 2023 were included. All patients underwent magnetic resonance imaging and cognitive assessments before and within 48 hours after the procedure. These evaluations were also repeated at 45‐day, 3‐month, 6‐month, and 1‐year follow up. Results Out of 75 patients included in the final analysis, 29 (38.7%) patients suffered from new SCE during LAAO. Patients with SCE exhibited a significant decline in cognitive function (Mini‐Mental State Examination) immediately after the procedure (P<0.001), which was not reversible during 1‐year follow‐up (P<0.001). Additionally, with time going on, the gap in cognitive function between patients with and without SCE became wider (SCE × 1 year: B=−4.81 [95% CI, −5.58 to −4.05]; P<0.001). New‐onset SCE was detected in 11 (14.7%) patients during the follow‐up magnetic resonance imaging, which also showed a decline in cognitive function (P=0.004). The results in Montreal Cognitive Assessment scores were consistent with Mini‐Mental State Examination. Conclusions LAAO‐related SCE is associated with a marked impairment in cognitive function immediately after the procedure and is irreversible over a 1‐year follow‐up. New magnetic resonance‐detected SCE during follow‐up after LAAO would also be associated with a decline in cognitive function.

BACKGROUND:Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) may impair gastric motility through collateral thermal injury. Pulsed field ablation (PFA), a nonthermal modality, is expected to preferentially affect the cardiomyocytes and spare gastric motility. OBJECTIVE:This study aimed to compare the effects of PFA and RFA for PVI on gastric motility in patients with atrial fibrillation (AF). METHODS:In this prospective matched study, patients undergoing PFA-PVI were compared with age- and sex-matched RFA-PVI parallel controls. Gastric motility, including gastric emptying and related symptoms, was assessed before and subsequently at 48 hours after the ablation. Gastric emptying was evaluated with the emptying rate of nondigestible radiopaque markers 5 hours after ingestion, and symptoms were assessed with standardized questionnaires. RESULTS:28 patients with paroxysmal AF were enrolled, with 14 in each group. Acute PVI was achieved without major complications in both groups. The gastric emptying rate (GER) remained unchanged after PFA (77.9% ± 32.9% vs 78.6% ± 29.0%, P = .98) but decreased after RFA (78.6% ± 24.2% vs 66.1% ± 30.2%, P < .05). The change in GER was significantly greater after RFA than PFA (12.5% ± 24.1% vs -0.7% ± 27.1%, P < .05). New-onset delayed gastric emptying occurred in 1 (7.1%) and 3 (21.4%) patients in the PFA-PVI and RFA-PVI groups, respectively. Post-procedural gastrointestinal symptom scores worsened significantly only in the RFA group. CONCLUSION:PFA causes significantly less damage to gastric motility than RFA during PVI, which translates into an improved quality of life for patients.

BACKGROUND:Ventricular arrhythmias (VAs), particularly those originating from intramural or deep myocardial layers, pose significant challenges in ablation therapy. CASE SUMMARY:A 42-year-old man with frequent ventricular tachycardia (VT) and declining ejection fraction was admitted for further ablation following 6 unsuccessful procedures. Activation mapping results indicated an intramural septal origin, and initial radiofrequency ablation was ineffective. Ethanol ablation through the coronary venous system was attempted but failed owing to unfavorable anatomical properties. A transcoronary approach was then pursued. We cannulated a guidewire into the first septal perforator branch of the left anterior descending artery, adjacent to the earliest mapped site. Ice-cold saline injection through the over-the-wire lumen terminated VT immediately. Subsequently, 0.5 mL of dehydrated ethanol (95%) was injected twice, and VAs were no longer inducible. DISCUSSION:Transcoronary ethanol ablation remains a viable alternative for intramural septal VAs when conventional and venous approaches are unsuccessful. TAKE-HOME MESSAGES:Transvascular ethanol ablation can serve as a bailout solution for VAs originating from the intramural septum. Although the transvenous approach has safety advantages, the transcoronary approach remains a viable alternative when no suitable veins are available.

BACKGROUND:The choice between left- and right-sided ablation for outflow tract premature ventricular complexes (OT-PVCs) during procedures remains a topic of ongoing discussion. In this study we aim to elucidate the value of the QRS-VHis interval in distinguishing between left and right origins in left bundle branch block (LBBB)-type OT-PVCs, thereby optimizing the ablation process. METHODS:The QRS-VHis interval was measured in consecutive patients with LBBB-type OT-PVCs. The performance of this interval was compared with traditional electrocardiographic (ECG) algorithms and prospectively validated in a cohort from 8 centers. Based on the interval, we developed an algorithm to assess its efficacy in optimizing the ablation process. RESULTS:A total of 166 patients were enrolled in the development cohort, and 53 patients in the validation cohort. The QRS-VHis interval demonstrated greater accuracy than ECG algorithms among 153 patients with typical endocardial origins (area under the curve = 0.962). At a cutoff of 30 ms, the QRS-VHis interval showed a sensitivity of 71.8% and a specificity of 98.2% for identifying left-sided locations. A flowchart was developed based on the QRS-VHis interval, indicating that a QRS-VHis value of < 30 ms necessitated left-sided ablation with a 94% likelihood, leading to an 88% success rate. Conversely, when the QRS-VHis value was ≥ 30 ms, the likelihood of requiring left-sided ablation dropped to only 16%. The accuracy of the flowchart was validated in the independent cohort. CONCLUSIONS:The QRS-VHis interval is superior for distinguishing between left and right ventricular outflow tract origins in LBBB-type OT-PVCs and has proven valuable in optimizing the intraprocedural process.

BACKGROUND:The circuit of scar-related upper loop macroreentry atrial flutter (AFL) surrounding the superior vena cava (SVC) has been described by prior case reports. However, the correlation between the circuit and arrhythmogenic substrates and the corresponding optimized ablation strategy need to be further investigated. OBJECTIVE:We aimed to identify the electrophysiologic substrate and corresponding ablation strategies of SVC-AFL using high-resolution mapping. METHODS:From June 1, 2017, to May 1, 2023, consecutive patients with macroreentrant atrial tachycardias (ATs) from 7 institutions were retrospectively evaluated. Patients with SVC-AFL were enrolled and analyzed. RESULTS:Of 1282 patients with macroreentrant ATs, 16 patients (1.2%; median age, 60.9 years; 8 male) had SVC-AFL (mean cycle length, 281.0 ± 55.1 ms), all identified during high-resolution activation mapping. All patients had prior cardiac surgery (14 [87.5%]) or catheter ablation (8 [50.0%]). A longitudinal surgical incision/scar extending from the SVC to the right atrium was observed in all patients, enabling macroreentry. SVC-AFLs with shorter circuits (<180 mm) had more slow conduction areas than those with longer circuits (>180 mm; 3.0 [2.0-4.0] vs 1.0 [1.0-1.5]; P = .023]. All ATs were terminated by ablating the channel between the surgical incision/scar and anatomic barriers. Cavotricuspid isthmus block was achieved in all patients. During a 21-month follow-up, all patients were free of atrial arrhythmias except for 4 patients experiencing short-lived paroxysmal ATs that did not require further ablation. CONCLUSION:A surgical incision/scar extending from the SVC to right atrium promotes the development of SVC-AFL. Substrate-based linear lesions along with prophylactic cavotricuspid isthmus ablation afford favorable clinical outcomes.