Language：English   Publisher：Journal of Cardiovascular Electrophysiology  

Introduction: Intrinsic antitachycardia pacing (iATP) is a novel automated antitachycardia pacing (ATP) that provides individual treatment to terminate ventricular tachycardia (VT). However, the clinical efficacy of iATP in comparison with conventional ATP is unknown. We aim to compare the termination rate of VT between iATP and conventional ATP in patients with implantable cardioverter-defibrillators using a unique setting of different sequential orders of both ATP algorisms. Methods: Patients with the iATP algorithm were assigned to iATP-first and conventional ATP-first groups sequentially. In the iATP-first group, a maximum of seven iATP sequences were delivered, followed by conventional burst and ramp pacing. In contrast, in the conventional ATP-first group, two bursts and ramp pacing were initially programmed, followed by iATP sequences. We compared the success rates of VT termination in the first and secondary programmed ATP zones between the two groups. Results: Fifty-eight and 56 patients were enrolled in the iATP-first and conventional ATP-first groups, and 67 and 44 VTs were analyzed in each group, respectively. At the first single ATP therapy, success rates were 64% and 70% in the iATP and conventional groups, respectively. At the end of the first iATP treatment zone, the success rate increased from 64% to 85%. Moreover, secondary iATP therapy following the failure of conventional ATPs increased the success rate from 80% to 93%. There was a significant benefit of alternative iATP for VT termination compared to secondary conventional ATP (100% vs. 33%, p =.028). Conclusions: iATP may be beneficial as a secondary therapy after failure of conventional ATP to terminate VT.

DOI： 10.1111/jce.16232

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Language：English   Publisher：Frontiers in Cardiovascular Medicine  

Torsades de Pointes (TdP) refers to a polymorphic ventricular tachycardia (VT) with undulating QRS axis that occurs in long QT syndrome (LQTS), although the term has been used to describe polymorphic ventricular tachyarrhythmias in which QT intervals are not prolonged, such as short-coupled variant of TdP currently known as short-coupled ventricular fibrillation (VF) and Brugada syndrome. Extensive works on LQTS-related TdP over more than 50 years since it was first recognized by Dessertennes who coined the French term meaning “twisting of the points”, have led to current understanding of the electrophysiological mechanism that TdP is initiated by triggered activity due to early afterdepolarization (EAD) and maintained by reentry within a substrate of inhomogeneous repolarization. While a recently emerging notion that steep voltage gradients rather than EADs are crucial to generate premature ventricular contractions provides additions to the initiation mode, the research to elucidate the maintenance mechanism hasn't made much progress. The reentrant activity that produces the specific form of VT is not well characterized. We have conducted optical mapping in a rabbit model of electrical storm by electrical remodeling (QT prolongation) due to chronic complete atrioventricular block and demonstrated that a tissue-island with prolonged refractoriness due to enhanced late Na+ current (INa−L) contributes to the generation of drifting rotors in a unique manner, which may explain the ECG characteristic of TdP. Moreover, we have proposed that the neural Na+ channel NaV1.8-mediated INa−L may be a new player to form the substrate for TdP. Here we discuss TdP mechanisms by comparing the findings in electrical storm rabbits with recently published studies by others in simulation models and human and animal models of LQTS.

DOI： 10.3389/fcvm.2024.1363848

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Language：English   Publisher：Journal of Interventional Cardiac Electrophysiology  

Background : Real-time phase mapping (ExTRa™) is useful in determining the strategy of catheter ablation for non-paroxysmal atrial fibrillation (AF). This study aimed to investigate the features of drivers of AF associated with its termination during ablation. Methods: Thirty-six patients who underwent catheter ablation for non-paroxysmal AF using online real-time phase mapping (ExTRa™) were enrolled. A significant AF driver was defined as an area with a non-passively activated ratio of ≥ 50% on mapping analysis in the left atrium (LA). All drivers were simultaneously evaluated using a low-voltage area, complex fractionated atrial electrogram (CFAE), and rotational activity by unipolar electrogram analysis. The electrical characteristics of drivers were compared between patients with and without AF termination during the procedure. Results: Twelve patients achieved AF termination during the procedure. The total number of drivers detected on the mapping was significantly lower (4.4 ± 1.6 vs. 7.4 ± 3.8, p = 0.007), and the drivers were more concentrated in limited LA regions (2.8 ± 0.9 vs. 3.9 ± 1.4, p = 0.009) in the termination group than in the non-termination group. The presence of drivers 2–6 with limited (≤ 3) LA regions showed a tenfold increase in the likelihood of AF termination, with 83% specificity and 67% sensitivity. Among 231 AF drivers, the drivers related to termination exhibited a greater overlap of CFAE (56.8 ± 34.1% vs. 39.5 ± 30.4%, p = 0.004) than the non-related drivers. The termination group showed a trend toward a lower recurrence rate after ablation (p = 0.163). Conclusions: Rotors responsible for AF maintenance may be characterized in cases with concentrated regions and fewer drivers on mapping.

DOI： 10.1007/s10840-023-01588-8

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Language：English   Publisher：Journal of Cardiovascular Electrophysiology  

Introduction: The clinical outcomes and mechanisms of delayed responses to cardiac resynchronization therapy (CRT) remain unclear. We aimed to investigate the differences in outcomes and gain insight into the mechanisms of early and delayed responses to CRT. Methods: This retrospective study included 110 patients who underwent CRT implantation. Positive response to CRT was defined as ≥15% reduction of left ventricular (LV) end-systolic volume on echocardiography at 1 year (early phase) and 3 years (delayed phase) after implantation. The latest mechanical activation site (LMAS) of the LV was identified using two-dimensional speckle-tracking radial strain analysis. Results: Seventy-eight (71%) patients exhibited an early response 1 year after CRT implantation. Of 32 non-responders in the early phase, 12 (38%) demonstrated a delayed response, and 20 (62%) were classified as non-responders after 3 years. During the follow-up time of 10.3 ± 0.5 years, the delayed and early responders had a similar prognosis of mortality and heart failure (HF) hospitalization. In contrast, non-responders had a worse prognosis. Multivariate analysis revealed that a longer duration (months) between initial HF hospitalization and CRT (odds ratio [OR]: 1.126; 95% confidence interval [CI]: 1.036–1.222; p =.005), non-exact concordance of LV lead location with LMAS (OR: 32.744; 95% CI: 1.101–973.518; p =.044), and pre-QRS duration (OR: 0.901; 95% CI: 0.827–0.981; p =.016) were independent predictors of delayed response to CRT compared with early response. Conclusion: The prognoses were similar regardless of the response time after CRT. A longer history of HF, suboptimal LV lead position, and shorter pre-QRS duration were related to delayed response than early response.

DOI： 10.1111/jce.16125

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Publisher：医歯薬出版(株)  

DOI： 10.32118/j01436.2024096747

CiNii Research

Language：English   Publisher：JACC: Clinical Electrophysiology  

DOI： 10.1016/j.jacep.2023.08.010

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Language：English   Publisher：Journal of Interventional Cardiac Electrophysiology  

Background: Few studies have reported on the quantitative evaluation of autonomic nerve modification after balloon ablation. Therefore, this study aimed to evaluate the effects of cryoballoon and hotballoon ablations on the autonomic nervous system (ANS) and their relationship with prognosis. Methods: We included 234 patients who underwent cryoballoon ablation (n = 190) or hotballoon ablation (n = 44) for paroxysmal atrial fibrillation. Heart rate variability (HRV) analysis was performed on all patients using a 3-min electrocardiogram at baseline, 1, 3, 6, and 12 months after ablation. HRV parameters and prognoses were compared between the two balloon systems. Results: Ln low-frequency (LF), Ln high-frequency (HF), standard deviation of the R-R intervals (SDNN), and RR intervals significantly decreased after 1 month in both groups, but the changes were more pronounced in the cryoballoon group than in the hotballoon group. In contrast, HRV indices in the hotballoon ablation group decreased gradually and reached their lowest point 3-to-6 months after the procedure, which was later than in the cryoballoon ablation group. The recurrence rate did not differ between the two groups. HRV parameters changed similarly in the cryoballoon group, regardless of recurrence. However, patients with recurrence had significantly higher SDNN and Ln LF at 12 months than those without recurrence in the hotballoon group (41.2 ± 39.3 ms vs. 18.5 ± 12.6 ms, p = 0.006, and 2.2 ± 0.7 ms2 vs. 1.5 ± 0.7 ms2, p = 0.003, respectively). Conclusions: The time course of HRV changes differed between cryoballoon and hotballoon ablations. Hence, the two balloon systems may have distinct effects on the ANS and its role in prognosis. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s10840-023-01581-1

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Language：English   Publisher：PACE - Pacing and Clinical Electrophysiology  

Deep septal ventricular pacing is a recently developed physiological pacing modality with good efficacy; however, it has a potential risk of unusual complications. Here, we report a patient with pacing failure and spontaneous, complete lead dislodgement after >2 years of deep septal pacing, possibly caused by systemic bacterial infection and specific lead behavior in the septal myocardium. This case report may implicate a hidden risk of unusual complications in deep septal pacing.

DOI： 10.1111/pace.14688

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Language：English   Publisher：Journal of Cardiovascular Electrophysiology  

Introduction: Diagnosis of outflow tract ventricular arrhythmia (OTVA) localization by an electrocardiographic complex is key to successful catheter ablation for OTVA. However, diagnosing the origin of OTVA with a precordial transition in lead V3 (V3TZ) is challenging. This study aimed to create the best practical electrocardiogram algorithm to differentiate the left ventricular outflow tract (LVOT) from the right ventricular outflow tract (RVOT) of OTVA origin with V3TZ using machine learning. Methods: Of 498 consecutive patients undergoing catheter ablation for OTVA, we included 104 patients who underwent ablation for OTVA with V3TZ and identified the origin of LVOT (n = 62) and RVOT (n = 42) from the results. We analyzed the standard 12-lead electrocardiogram preoperatively and measured 128 elements in each case. The study population was randomly divided into training group (70%) and testing group (30%), and decision tree analysis was performed using the measured elements as features. The performance of the algorithm created in the training group was verified in the testing group. Results: Four measurements were identified as important features: the aVF/II R-wave ratio, the V2S/V3R index, the QRS amplitude in lead V3, and the R-wave deflection slope in lead V3. Among them, the aVF/II R-wave ratio and the V2S/V3R index had a particularly strong influence on the algorithm. The performance of this algorithm was extremely high, with an accuracy of 94.4%, precision of 91.5%, recall of 100%, and an F1-score of 0.96. Conclusions: The novel algorithm created using machine learning is useful in diagnosing the origin of OTVA with V3TZ.

DOI： 10.1111/jce.15823

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Language：English   Publisher：F1000Research  

Background: Currently, the standard curative treatment for ventricular tachycardia (VT) and ventricular fibrillation (VF) is radiofrequency catheter ablation. However, when the VT circuit is deep in the myocardium, the catheter may not be delivered, and a new, minimally invasive treatment using different energies is desired. Methods: This is a protocol paper for a feasibility study designed to provide stereotactic radiotherapy for refractory VT not cured by catheter ablation after at least one catheter ablation. The primary end point is to evaluate the short-term safety of this treatment and the secondary endpoint is to evaluate its efficacy as assessed by the reduction in VT episode. Cyberknife M6 radiosurgery system will be used for treatment, and the prescribed dose to the target will be 25Gy in one fraction. The study will be conducted on three patients. Conclusion: Since catheter ablation is the only treatment option for VT that is covered by insurance in Japan, there is currently no other treatment for VT/VF that cannot be cured by catheter ablation. We hope that this feasibility study will provide hope for patients who are currently under the stress of ICD activation. Trial registration: The study has been registered in the Japan Registry of Clinical Trials (jRCTs042230030).

DOI： 10.12688/f1000research.138758.2

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Language：English   Publisher：Journal of Interventional Cardiac Electrophysiology  

Background: The adaptive cardiac resynchronization therapy (aCRT) algorithm automatically produces synchronized left ventricular pacing (sLVP) with intrinsic atrioventricular conduction to improve clinical outcomes. However, relationship between sLVP percentage and risk for ventricular tachyarrhythmia (VT/VF) remains unclear. This study aimed to evaluate the clinical impact of sLVP rate on VT/VF occurrence. Methods: In total, 1,419 device interrogation data from 42 consecutive patients who underwent new aCRT device implantation were retrospectively analyzed. The primary endpoint was the first time VT/VF episode after aCRT device implantation. Results: During a median follow-up of 34 months, 15 patients had VT/VF episodes. Patients were divided into a high sLVP (the average sLVP percentage of ≥ 51.5%, n = 27) or low sLVP group (< 51.5%, n = 15). The high sLVP group had a significantly lower VT/VF incidence (22% vs. 60%; p = 0.014) and an independent predictor for VT/VF occurrence on multivariate analysis (hazard ratio 0.21; p = 0.007). LV ejection fraction improvements after 6 months (12.3 ± 8.7% vs. 2.8 ± 10.3%; p = 0.004) and 12 months (13.8 ± 9.3% vs. 6.2 ± 11.1%; p = 0.030) were significantly greater in the high sLVP group than in the low sLVP group. Age, PR interval, and left atrial diameter were significantly associated with the sLVP rate after aCRT. Conclusions: Patients with high sLVP percentage after aCRT had lower long-term risk of VT/VF incidence with a favorable response to CRT. A synchronized pacing algorithm using intrinsic conduction may prevent malignant arrhythmias, as well as recover cardiac functions.

DOI： 10.1007/s10840-022-01284-z

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Language：English   Publisher：Annals of Noninvasive Electrocardiology  

Background: The current study aimed to evaluate changes in electrical depolarization and repolarization parameters after His-bundle pacing (HBP) compared with right ventricular pacing (RVP) and its association with ventricular arrhythmia (VA). Methods: Forty-one patients (13 with HBP, 14 with RVP, and 14 controls [AAI mode]) were evaluated. After continuous pacing algorithm, QRS duration, QT interval, QTc, JT interval, T-peak to T-end (Tpe), and Tpe/QT ratio were measured on electrocardiography at baseline and 1 week, 1 month, and 6 months postoperatively. We investigated VA occurrence and adverse events after implantation. Results: At 6 months, QRS duration was significantly shorter in the HBP (121.6 ± 15.6 ms) than in the RVP (150.1 ± 14.9 ms) group. The QT intervals were lower in the HBP (424.0 ± 40.9 ms) and control (405.9 ± 23.0 ms) groups than in the RVP (453.0 ± 40.2 ms) group. The Tpe and Tpe/QT ratios at 6 months differed significantly between the HBP and RVP groups (Tpe, 69.8 ± 19.7 ms vs 87.4 ± 11.9 ms and Tpe/QT, 0.16 ± 0.03 vs 0.19 ± 0.02, respectively). The Tpe and Tpe/QT ratios were similarly shortened in the HBP and control groups. VA occurred less frequently in the HBP (15%) and control (7.1%) groups than in the RVP (50%) group (p = 0.020). The non-RVP group showed significantly lower rates of VA and major adverse events than the RVP group. Patients with VA demonstrated significantly longer QRS duration, QT interval, Tpe, and Tpe/QT at 6 months than those without VA. Conclusion: HBP showed better depolarization and repolarization stability than RVP.

DOI： 10.1111/anec.12991

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Language：English   Publisher：Journal of Cardiovascular Electrophysiology  

Introduction: Reactive atrial-based antitachycardia pacing (rATP) in patients with cardiac implantable electronic devices (CIEDs) suppresses the progression of atrial fibrillation (AF) to the persistent form. However, the clinical factors associated with successful reactive atrial-based antitachycardia pacing (rATP) treatment are unknown. This study aimed to examine the predictors of high rATP efficacy in patients with CIEDs. Methods: The data of 101,325 rATP-treated atrial tachyarrhythmia (AT/AF) episodes in 51 patients, obtained through remote monitoring and device interrogation, were analyzed. The study population was divided into the high and low efficacy groups based on the overall median success rate of rATP. Clinical characteristics were compared between the two groups. Results: During a follow-up period of 28.6 ± 8.6 months, the median success rate was 43.7% (31.5%–64.9%). The prevalence of a history of catheter ablation of AF was significantly higher in the high efficacy group than in the low efficacy group (73.0% vs. 44.0%, p =.048) and was the only independent predictor of high rATP efficacy (odds ratio, 3.45; p =.038). The rATP success rate in patients with (n = 30) and without (n = 21) a history of catheter ablation was 53.9% (40.0%–67.5%) and 36.4% (22.2%–47.7%), respectively (p =.012). The effect of rATP after ablation was more pronounced in patients with long cycle length episodes (≥75% of AT/AF sequences having a cycle length of 200–449 ms) (67.3% [46.0%–73.6%] vs. 30.6% [18.1%–60.3%], p =.027). The high efficacy group had a significantly lower incidence of AT/AF lasting ≥1, ≥7, and ≥30 days than the low efficacy group. Conclusion: rATP combined with catheter ablation therapy is effective in suppressing AT/AF.

DOI： 10.1111/jce.15551

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Language：Japanese   Publisher：JACC: Clinical Electrophysiology  

Background: Catheter ablation for ventricular tachycardia (VT) is associated with perioperative thromboembolic risk. However, the strategy for postprocedural management remains unknown. Objectives: The aim of this study was to evaluate the prothrombotic response after VT ablation in various coagulation biomarkers in patients with and without the administration of oral anticoagulation (OAC). Methods: Data from 112 patients (58 with uninterrupted OAC and 54 without) with structural heart disease who underwent endocardial VT ablation were retrospectively analyzed. We also included 41 patients who underwent ablation for premature ventricular contraction from the right ventricle and 13 patients who underwent electrophysiology study (the control group). Blood samples of coagulation markers were collected before and 3 days after the procedure in all patients. Results: The percentage of D-dimer levels ≤1.0 μg/mL at baseline was lower in the VT ablation groups (76% and 50% in the OAC and non-OAC groups, respectively) than in the other groups (100%). After 3 days, the percentage remained at 67% in the OAC group; however, the non-OAC VT group demonstrated a remarkable decrease of 20%. Similarly, fibrin monomer complex, thrombin antithrombin, and prothrombin fragment 1+2 levels were well suppressed in the control, premature ventricular contraction, and OAC groups. However, the non-OAC group demonstrated increased coagulation markers both before and after 3 days. Multivariate analysis demonstrated that OAC administration and normal coagulation markers at baseline were independent predictors of stable coagulation status after ablation. Conclusions: The coagulation cascade was significantly activated in patients undergoing VT ablation. Uninterrupted OAC administration suppressed the coagulation response, which might be associated with a reduction in perioperative prothrombotic risk.

DOI： 10.1016/j.jacep.2022.02.015

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Language：English   Publisher：International Heart Journal Association  

<p>We report the usefulness of novel automated anti-tachycardia pacing (ATP) for ventricular tachycardia (VT) termination evaluated in an electrophysiology study. This intrinsic, automated ATP with an implanted cardiac resynchronization therapy-defibrillator successfully terminated the sustained VT, which had not been suppressed by repetitive burst pacing from the electrode catheter. The reproduction of programed pacing of the automated ATP by a right ventricular electrode catheter was effective in terminating VT, and this termination was absolute and reproducible. Further detailed assessment in an electrophysiology study could highlight the algorithm of the automated ATP and its possible benefit in terminating the reentrant VT.</p>

DOI： 10.1536/ihj.21-755

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CiNii Research

Language：English   Publisher：Heart and Vessels  

Focal activation is believed to be an atrial fibrillation (AF) driver; however, little is known about whether all focal activations are necessary for AF persistence. The purpose of this study was to assess the electrical nature of focal activation and identify high-priority focal activations using a novel mapping system (CARTOFINDER). Thirty-five patients with persistent AF who underwent catheter ablation were assessed. Cycle length (CL) and CL standard deviation (CLSD) on unipolar recordings and voltage amplitude and electrogram morphologies on bipolar recordings were evaluated at all points of interest. The most frequent CL at each mapping site was defined as the dominant CL. We identified dominant focal activations (DFAs) that had a shorter dominant CL on the integrated CARTOFINDER map. The effect of elimination of DFAs on AF maintenance was assessed by the composite endpoint (termination to sinus rhythm, organization of the rhythm to atrial tachycardia, and AF CL slowing). In all, 450 focal activations were identified among 10,868 points, and 50.4% of focal activations were DFAs. Focal activations showed relatively long CL and regularity with short CLSD. Most focal activations showed an isoelectric baseline and were located outside of the fractionated electrogram area. Both DFAs and non-DFAs were typically observed in the normal voltage range. Elimination of DFAs was achieved in 19 (54.3%) patients, with a remarkable impact on AF maintenance (68.4% vs. 25.0%, p = 0.018). In conclusion, DFAs may play an important role in AF maintenance and could be an attractive therapeutic target for AF.

DOI： 10.1007/s00380-021-01977-x

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