Masahiko Goya

Background: The Asia‐Pacific Heart Rhythm Society Atrial Fibrillation (APHRS‐AF) Registry is a prospective study in Asian metropolitan cities, which provides important information on the baseline characteristics, therapeutic patterns, and 1‐year clinical outcomes in patients with atrial fibrillation (AF). This report describes data from Japanese patients recruited in this registry. Methods and Results: A total of 4666 patients with AF were enrolled. Of these, 794 patients were recruited from 28 large cardiovascular centers in Japan between 2015 and 2017. We analyzed 1‐year follow‐up outcome of these patients. Mean age at recruitment was 65.7 years and 69.0% were males. Major comorbidities were hypertension (37.5%), lipid disorder (29.0%), heart failure (15.9%), and diabetes mellitus (15.0%). Mean CHADS2 score, CHA2DS2‐VASc score, and HAS‐BLED score were 1.0, 2.0, and 1.1, respectively. At baseline, use of oral anticoagulants was 81%, including 7% prescribed a vitamin K antagonist (VKA) and 74% a direct oral anticoagulant (DOAC). Majority of the patients ( N = 459, 57.8%) were planned to undergo catheter ablation. One‐year follow‐up was conducted in 743 patients. One‐year all‐cause mortality was 0.1% ( n = 1) and the incidence of stroke/thromboembolic events was also 0.1% ( n = 1). Major bleeding events were observed in 5 patients (0.7%), including 3 intracranial hemorrhages. Conclusion: In this 1‐year analysis, a high prevalence of oral anticoagulant use was recorded. A low mortality rate and a low incidence of stroke/thromboembolic events were observed in Japanese patients of the APHRS‐AF Registry.

The Japanese Heart Rhythm Society established a nationwide, mandatory, multi‐center, prospective, observational registry of transvenous lead extraction (TLE) named the Japanese lead extraction registry (J‐LEX) in 2018. As of the end of 2024, a cumulative total of approximately 5400 cases has been registered across 140 participating centers since 2018. The registry includes all consecutive transvenous extractions, excluding surgical‐only cases. The indication of TLE was an infection in 54.5%, and the guideline classification was class I in 59.8% and class IIa in 21.8%. As for non‐infectious indications, TLE is performed for abandoned leads in case of lead failure or device upgrade, and for lead‐related trouble such as pain, vessel stenosis or occlusion, too many leads, tricuspid valve regurgitation, and difficulty with radiation therapy. In 2024, the TLE procedure was attempted on patients with a median age of 71.3 years, female in 32.7%, in the hybrid operating room in 73.3%, and in a standard OR with a C‐arm fluoroscope in 11.5%. The average implantation duration of the target leads was 8.5 years. Complete removal was achieved in 96.7% of the target leads, and clinical success in 97.3% of the patients. Perioperative complications were observed in 4.8% of the patients. Three patients died during a TLE operation, and 11 patients died in‐hospital (cardiac death in three patients and non‐cardiac death in eight patients).

Antitachycardia pacing (ATP) therapy, available in modern implantable cardioverter defibrillators (ICD) and cardiac resynchronization therapy defibrillators (CRT-D), aims to terminate ventricular arrhythmias without administering high energy shocks. The intrinsic ATP (iATP) algorithm automates ATP programming in real-time, tailoring therapy based on previous ATP attempts. This study evaluated the safety, efficacy, and clinical outcomes of iATP in patients from Japan and South Korea. This study was a prospective, observational, multi-site registry that enrolled patients from Japan and South Korea implanted with an ICD or CRT-D device with the iATP algorithm. Patients were followed for a minimum of 12 months. Outcomes included ATP termination success, appropriate shocks, acceleration, arrhythmia-related syncope, and mortality. A post hoc unanchored matching-adjusted indirect comparison (uMAIC) was performed to compare iATP with standard ATP using published literature. A total of 800 patients were enrolled. The iATP success rate for terminating all episodes was 89.2% (86.2% Generalized Estimating Equation [GEE] estimated) and 82.2% for episodes in the fast VT zone (80.9% GEE estimated). Acceleration occurred in 2.0% of episodes, and arrhythmia-related syncope was observed in 0.5% of patients. The 1-year survival rate was 96.1%, with no device-related deaths or abnormal battery depletions. The uMAIC showed iATP had higher termination efficacy across all episodes (88.1% vs. 79.3%, P < 0.001), a lower probability of appropriate shocks per episode (iATP 14.7% and ATP 31.3%, P < 0.001), and fewer accelerations per episode (2.1% vs. 4.8%, P = 0.02), with similar probability of arrhythmia-related syncope per patient (0.5% vs 0.9%, P = 0.35) and mortality (12-month Kaplan Meyer survival estimate iATP 95.4%, ATP 95.3%, P = 0.43). iATP exhibited a high ventricular arrhythmia termination efficacy and a favorable safety profile. Comparison of iATP to standard ATP provides initial evidence of higher termination success, lower incidence of accelerations and appropriate shocks, and similar rates of mortality and arrhythmia-related syncope.Trial Registration: ClinicalTrials.gov Identifier: NCT01524276; Japan Registry of Clinical Trials Identifier: jRCT1042200049.

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.

Background: The effectiveness of cryoballoon ablation (CBA) of the left atrial (LA) roof in addition to pulmonary vein isolation (PVI) using a novel cryoballoon catheter, POLARx, remains unclear.Methods: This study compared the efficacy of LA roof line ablation and PVI using POLARx (Boston Scientific) or AFA‐Pro (Medtronic) in 100 patients with persistent atrial fibrillation. The right superior pulmonary vein (PV) anchoring and raise‐up techniques were consistently used for LA roof line ablation, and rapid right ventricular pacing was applied if the cryoballoon temperature did not reach −40°C.Results: Complete conduction block at the LA roof could be obtained in all patients with POLARx and in 98.0% of patients with AFA‐Pro. Rapid right ventricular pacing was needed in 64.0% of patients with AFA‐Pro and in no patients with POLARx. During LA roof line ablation, the nadir cryoballoon temperature was significantly lower with POLARx than with AFA‐Pro (right: −54.2°C ± 4.4°C vs. −46.0°C ± 5.4°C; central: −56.8°C ± 4.4°C vs. −45.7°C ± 4.8°C; left: −56.1°C ± 4.3°C vs. −46.1°C ± 5.7°C), and the cryoballoon temperature reached −40°C earlier with POLARx than with AFA‐Pro (right: 30.8 ± 7.4 s vs. 74.1 ± 37.7 s; central: 28.2 ± 5.2 s vs. 62.9 ± 30.9 s; left: 29.8 ± 5.8 s vs. 69.6 ± 40.7 s).Conclusion: The nadir cryoballoon temperature with POLARx was approximately 10°C lower than with AFA‐Pro, consistently dropping below −40°C during LA roof line CBA. Thus, a complete conduction block of the LA roof line can be easily accomplished using right superior PV anchoring and the raise‐up techniques without the need for rapid right ventricular pacing with POLARx.

Background: Bipolar radiofrequency catheter ablation (BRFA) is a potential treatment for refractory ventricular arrhythmias from deep myocardial tissue. However, clear indicators of efficacy and safety remain undefined. Methods: In an ex vivo model, BRFA was performed using either the QDOT Micro™ (QDT) or Thermocool SmartTouch SF™ as the active catheter, with the DiamondTemp Ablation™ (DTA) as the return catheter. Predictors of transmural lesion formation and steam-pop occurrence were assessed. Results: A total of 391 BRFA applications were performed with variations in the interelectrode distance between the active and return catheter tips, ranging from 6 to 27 mm, under various catheter tip and tissue contact configurations. The ablation index (AI) adjusted for inter-electrode distance effectively predicted transmural lesion formation. Logistic regression analysis revealed a coefficient for AI of −0.040 (SE: 0.0067; 95% CI: [−0.053, −0.027]; p < 0.0001) and for inter-electrode distance of 2.2 (SE: 0.35; 95% CI: [1.5, 2.9]; p < 0.0001). The decision boundary for transmural lesion formation was AI = 54 × inter-electrode distance – 260. When AI exceeded this value, sensitivity, specificity, and positive and negative predictive values for predicting transmural lesions were 89%, 92%, 91%, and 90%, respectively. When the AI was further increased by 50, the specificity reached 100%. Steam-pops on the active catheter side occurred only during power-controlled BRFA and were absent in temperature-controlled BRFA with a 45°C cutoff. On the return side, steam-pops occurred when DTA temperature exceeded 55°C, with deeper cracks observed above 60°C. Conclusions: An AI adjusted for inter-electrode distance strongly predicted transmural lesions. Temperature-controlled BRFA with a 45°C cutoff for QDT as the active catheter and 55°C for DTA as the return catheter may prevent steam-pops. Additionally, steam-pops occurring at higher catheter tip temperatures were associated with deeper tissue cracks. Clinical Perspective: What is known? Bipolar radiofrequency ablation has shown promise as an effective treatment option for ventricular arrhythmias originating from deep regions of the ventricular myocardium. The indicators for successful transmural lesion formation and the predictors for steam-pop are not yet well understood, and the accuracy of conventional metrics remains limited. What the study adds The ablation index (AI) necessary for achieving successful transmural lesion formation during bipolar radiofrequency ablation, using a QDOT micro™ (QDT) as the active catheter and a DiamondTemp Ablation™ (DTA) the return catheter, can be determined using the formula: AI = 54 × inter-electrode distance – 260, where the inter-electrode distance denotes the distance between the active and return electrodes. During bipolar radiofrequency ablation, performing temperature-controlled ablation with a temperature cutoff of 45°C for the QDT and 55°C for the DTA may help prevent steam-pop. Furthermore, the higher the DTA temperature at the time of steam-pop, the deeper the cracks that are formed.

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: The clinical outcome of pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF) is suboptimal. Mapping studies have demonstrated atrial sites outside of the pulmonary veins displaying focal activation patterns during AF. We sought to determine whether adding catheter ablation of focal activation sites to PVI improves clinical outcomes of catheter ablation for persistent AF. METHODS: In this multicenter, randomized, single-blinded trial, we assigned patients with persistent AF to either PVI alone or to mapping-guided ablation of focal activation sites in addition to PVI in a 1:1 ratio. In the mapping-guided group, both atria were mapped after PVI using a Pentaray catheter (Biosense-Webster) and focal activation sites identified by CARTOFINDER (Biosense-Webster) were ablated. The primary end point was freedom from AF or atrial tachycardia without antiarrhythmic drugs beyond a 90-day blanking period. RESULTS: A total of 98 patients were assigned to the mapping-guided group and 102 to the PVI alone group. In the mapping-guided group, focal activation sites were identified at 2.6±0.3 and 2.5±0.2 sites per patient in the left and right atrium, respectively. Patients were followed up for 768.5 (interquartile range, 723.75–915.75) and 755.5 days (interquartile range, 728.5–913.75) in the mapping-guided ablation and the PVI alone groups, respectively. Freedom from AF/atrial tachycardia without antiarrhythmic drugs at 2-year follow-up was 66.8% and 75.2% in the mapping-guided ablation and the PVI alone groups, respectively (hazard ratio, 1.26 [95% CI, 0.76–2.10]; P =0.37). Adverse events occurred in 3 patients (3.0%) and none (0%) in the mapping-guided ablation and the PVI alone groups, respectively ( P =0.12). CONCLUSIONS: In patients with persistent AF, the addition of mapping-guided ablation of focal activation sites to PVI did not improve clinical outcomes compared with PVI alone. REGISTRATION: URL: https://center6.umin.ac.jp/cgi-open-bin/ctr/index.cgi?function=02 ; Unique identifier: UMIN000037569.

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.