Tomomasa Takamiya

Paced QRS duration ≥150 ms is associated with pacing‐induced cardiomyopathy (PICM). However, there is no established method for conventional stylet‐driven pacing lead placement to achieve a narrow QRS duration. We placed a pacing lead on the right ventricular inflow tract (RVIT) mid‐septum using a manually shaped three‐dimensional (3D) stylet and three‐directional fluoroscopic guidance in 9 consecutive patients with complete or advanced atrioventricular block and normal left ventricular systolic function. The median paced QRS duration was 140 (range, 122–153) ms, with a paced QRS duration <150 ms in 8 patients. The left superior axis and transitional zone of lead‐V5 or lead‐V6 were the most paced QRS morphologies. RVIT mid‐septal lead placement using a 3D stylet with three‐directional fluoroscopic guidance may reduce the incidence of PICM.

Introduction: The suitability of high‐power short‐duration (HPSD) cavo‐tricuspid isthmus ablation (CTI‐Abl) for electrophysiology (EP) trainees, as well as the underlying mechanisms of its efficacy, remain unknown. The aim of this study was to clarify the efficacy and safety of HPSD CTI‐Abl performed by EP trainees and assess lesion characteristics between HPSD and moderate‐power long duration (MPLD) ablations.Methods: Study 1: CTI‐Abl was performed by first‐ to fourth‐year EP trainees in consecutive 113 patients (67 ± 11 years, 27.2% female). Study cohort was historically divided into three groups: MPLD (30–35 W for up to 30 s) using TactiCath (TC‐MPLD, N = 38) and MPLD and HPSD (50 W for 12 s) using TactiFlex (TF‐MPLD, N = 23; TF‐HPSD, N = 52). Primary endpoint was first‐pass bidirectional isthmus block (BIB). Study 2: lesion geometries created by each ablation strategy were compared using an ex‐vivo model.Results: Study 1: TF‐HPSD ablation strategy demonstrated a higher success rate of first‐pass BIB than MPLD protocol (TC‐MPLD, 58%; TF‐MPLD, 48%; TF‐HPSD, 94%, p < 0.001), without any complications. TF‐HPSD group was associated with shorter total procedure and RF application times, as well as fewer ablation points and gaps, compared to the MPLD groups. Study 2: TF‐HPSD created greater lesion surface length, width, and area than MPLD strategies.Conclusion: HPSD CTI‐Abl performed by EP trainees using TactiFlex SE catheter demonstrated a higher first‐pass BIB rate, shorter total procedure and RF application times, and fewer ablation points and gaps compared to the conventional method, without increasing complication rates.

Purpose: Very high‐power short‐duration (vHPSD) ablation creates shallower lesions, potentially reducing efficacy. This study aims to identify factors leading to insufficient lesions during pulmonary vein antral isolation (PVAI) with vHPSD‐ablation and to develop an optimized PVAI strategy using this technology.Methods: PVAI was performed on 41 atrial fibrillation patients using vHPSD‐ablation (90 W/4 s). Lesion parameters were recorded and analyzed to identify predictors of insufficient lesions. An optimized PVAI strategy, based on these predictors, was tested in subsequent 42 patients.Results: In total, 3099 RF‐applications, including 103(3.3%) insufficient lesions, were analyzed. First‐pass PVAI was achieved in 19/40(47.5%) right PVs and 24/41(58.5%) left PVs. Multivariate analysis identified significant predictors of insufficient lesions: local largest bipolar voltage (Bi‐V), average contact force, baseline impedance, impedance drop, temperature rise, inter‐lesion distance (ILD), and anatomical location (carina or not). An ILD:4‐6 mm increased the risk of insufficient lesions 2.2‐fold, and lesions at the carina increased it 3.6‐fold for both ILD < 4 mm and ILD:4‐6 mm. Local largest Bi‐V was the strongest predictor for insufficient lesions. The optimized PVAI approach, utilizing vHPSD‐ablation with an ILD < 4 mm in non‐carinal areas with Bi‐V < 4 mV, and high‐power ablation‐index guided ablation (HPAI, 50 W, ablation‐index:450–550) in remaining areas, achieved first‐pass PVAI in 92.7% of right PVs and 88.1% of left PVs, using vHPSD‐ablation in approximately 65% of total RF‐applications. The optimized PVAI achieved significantly higher first‐pass PVI rate (p < .0001) with shorter ablation time (p = .04).Conclusion: Appropriate use of vHPSD and HPAI, based on local largest Bi‐V and anatomical information, may achieve high first‐pass PVAI rates in shorter ablation time with minimal energy delivery.

Background: We explore an optimized approach for increasing lesion size using a novel ablation catheter with a surface thermocouple and efficient irrigation in a temperature‐control setting.Methods: We conducted radiofrequency applications at various power levels (35 W, 40 W, and 45 W), contact forces (CFs, 10 g/20 g), and durations (60 s/120 s/180 s) in perpendicular/parallel catheter orientations, with normal saline irrigation (NS‐irrigation) and Half NS‐irrigation (HNS‐irrigation) in an ex‐vivo model (Step 1). In addition, we performed applications (35 W/40 W/45 W for 60 s/120 s/180 s in NS‐irrigation and 35 W/40 W for 60 s/120 s/180 s in HNS‐irrigation) in four swine (Step 2), evaluating lesion characteristics and the occurrence of steam pops.Results: In Step 1, out of 288 lesions, we observed 47 (16.3%) steam pops, with 13 in NS‐irrigation and 34 in HNS‐irrigation (p = .001). Although steam pops were mostly observed with the most aggressive setting (45 W/180 s, 54%) with NS‐irrigation, they happened in less aggressive settings with HNS irrigation. Lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. The optimal %impedance‐drop cutoff to predict steam pops was 20% with a negative‐predictive‐value (NPV) = 95.1% including NS‐ and HNS‐irrigation groups, and 22% with an NPV = 96.1% in NS‐irrigation group. In Step 2, similar to the ex‐vivo model, lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. Steam pops were absent with NS‐irrigation (0/35) even with the largest %impedance‐drop reaching 31% at 45 W/180 s. All steam pops were observed with HNS‐irrigation (6/21, 29%). The optimal %impedance‐drop cutoff predicting steam pops was 24% with an NPV = 96.3% including both NS‐ and HNS‐irrigation groups.Conclusions: Rather than using HNS‐irrigation, very long‐duration of radiofrequency applications up to 45 W/180 s may be recommended to safely and effectively increase lesion dimensions using this catheter with NS‐irrigation.

Aims: The usefulness of coronary venous system mapping has been reported for assessing intramural and epicardial substrates in patients with scar-related ventricular tachycardia (VT). However, there has been little data on mapping from coronary arteries. We investigated the safety and utility of mapping from coronary arteries with a novel over-the-wire multielectrode catheter in scar-related VT patients. Methods and results: Ten consecutive scar-related VT patients with non-ischaemic cardiomyopathy who underwent mapping from a coronary artery were analysed. Six patients underwent simultaneous coronary venous mapping. High-density maps were created by combining the left ventricular endocardium and coronary vessels. Substrate maps were created during the baseline rhythm with 2438 points (IQR 2136–3490 points), including 329 (IQR 59–508 points) in coronary arteries. Abnormal bipolar electrograms were successfully recorded within coronary arteries close to the endocardial substrate in seven patients. During VT, isthmus components were recorded within the coronary vessels in three patients with no discernible isthmus components on endocardial mapping. The ablation terminated the VT from an endocardial site opposite the earliest site in the coronary arteries in five patients. Conclusion: The transcoronary mapping with an over-the-wire multielectrode catheter can safely record abnormal bipolar electrograms within coronary arteries. Additional mapping data from the coronary vessels have the potential to assess three-dimensional ventricular substrates and circuit structures in scar-related VT patients.

Introduction: Non‐pulmonary vein (PV) triggers are a major cause of atrial tachyarrhythmia (ATA) recurrence after catheter ablation. However, the effect of the diagnosis‐to‐ablation time (DAT) on non‐PV triggers in persistent atrial fibrillation is unknown.Methods and Results: This observational study evaluated 502 consecutive persistent AF patients who underwent initial ablation. We compared 408 patients whose DAT was p = .025) especially with a higher prevalence of coronary sinus/inferior left atrial triggers. During a median follow‐up of 770 days, the ATA recurrence‐free rate was higher in the DAT < 3 years group than the DAT ≥ 3 years group (79% vs. 53% at 2 years, p < .001). In a multivariate analysis, female sex (odds ratio: 2.70, p = .002) and a longer DAT (odds ratio: 1.13/year, p = .008) were predictors of non‐PV AF/AT triggers, and a longer DAT (hazard ratio: 1.12/year, p < .001) and non‐PV AT/AF triggers (hazard ratio: 1.79, p = .009) were associated with ATA recurrence.Conclusion: Early ablation after the first diagnosis of persistent AF may reduce emerging non‐PV AF/AT triggers and ATA recurrence.

Purpose We examined the characteristics of non-pulmonary vein (PV) triggers in repeat ablation after cryoballoon ablation for paroxysmal atrial fibrillation (PAF). Methods This study evaluated 119 patients undergoing a second ablation procedure for recurrent atrial tachyarrhythmia (ATA) after cryoballoon PV isolation (CB-PVI) for PAF. Results Fifty-three of 119 (45%) patients had PV reconnection. All reconnected PVs were isolated. No non-PV triggers were elicited in 42/119 (35%) patients (NNPV group). In 77/119 (65%) patients, 139 isoproterenol-induced non-PV triggers, including 45 triggers that initiated AF, were identified. Non-PV triggers initiating AF were observed at the superior vena cava (SVC), left atrial posterior wall (LAPW) including the PV antra, interatrial septum, right atrium, left atrial appendage/mitral anulus, and coronary sinus in 14 (12%), 10 (8%), 8 (7%), 7 (6%), 4 (3%), and 2 (2%) patients, respectively. Non-PV triggers originated from only the SVC and/or LAPW including the PV antra, and the SVC and/or LAPW was isolated in 18/119 (15%) patients (SVC/LAPW group). Non-PV triggers originating from other sites were focally ablated in 59/119 (50%) patients (OS group). During a median 461 days of follow-up, 39/42 (93%), 17/18 (94%), and 38/59 (64%) patients in the NNPV, SVC/LAPW, and OS groups, respectively, remained ATA recurrence-free. The recurrence rate was higher in the OS group than in the NNPV (P = 0.005) or SVC/LAPW groups (P = 0.042). Conclusions Over half of patients had non-PV triggers at subsequent ablation after CB-PVI. Non-PV triggers from the SVC/LAPW can be eliminated more successfully than triggers from other sites.

Introduction Little evidence exists regarding cryoballoon ablation (CBA) of paroxysmal atrial fibrillation (PAF) in hemodialysis (HD) patients. We compared CBA and radiofrequency ablation (RFA) of PAF in HD patients, referring to CBA of PAF in non-HD patients. Methods and results This historical cohort study examined 88 patients who underwent catheter ablation of PAF, including 21 HD patients with a second-generation 28-mm cryoballoon (CB-HD group), 17 HD patients with a non-force-sensing radiofrequency catheter (RF-HD group), and 50 non-HD patients with a cryoballoon (CB-non-HD group). Pulmonary vein (PV) isolation alone aside from cavotricuspid isthmus ablation was performed in 14 (67%) in the CB-HD group, 12 (71%) in the RF-HD group, and 36 (72%) in the CB-non-HD group (P = 0.95), without isoproterenol-induced non-PV triggers. Non-PV trigger ablation was added to the other patients. The Kaplan–Meier estimated 1-year freedom from atrial tachyarrhythmia recurrence without antiarrhythmic drugs after a single procedure was 76%, 59%, and, 92% in the CB-HD, RF-HD, and CB-non-HD groups, respectively (P = 0.002). The mean procedure time was shorter in the CB-HD group than in the RF-HD group (127 vs. 199 min; P < 0.001). In the second procedure, the median number of reconnected pulmonary veins was 0.5 in the CB-HD group versus 2.0 in the RF-HD group (P = 0.17). Conclusion For PAF in HD patients, CBA showed a comparable single-procedure efficacy to that of RFA with a short procedure time. CBA may be a reasonable initial procedure for HD patients suffering from symptomatic PAF.