Balloon surface temperature-controlled ablation using a second-generation radiofrequency HotBalloon: an in vivo feasibility study.

AIMS: The first-generation radiofrequency HotBalloon (RHB) is a size-adjustable single-shot device used in atrial fibrillation. The energy output is determined by its central temperature and not by its balloon surface temperature (BST), thus limiting its efficacy and safety. Therefore, a second-generation RHB was developed to monitor BST and enable BST-controlled ablation. This animal study aims to evaluate the accuracy of a newly developed BST-monitoring system and validate the optimal BST for ablation. METHODS AND RESULTS: In Protocol 1, thermocapsules were attached to the superior vena cava (SVC) epicardium. The accuracy of BST monitoring was examined during SVC isolation. In Protocol 2, the efficacy and safety of different BST-controlled ablations were examined. In the acute model, electrophysiological and pathological findings were assessed after energy applications with BST at 51, 54, 57, and 60°C. In the chronic model, the lesion durability and pathological findings were assessed 8 weeks after BST-controlled ablation (57 and 60°C). A significant positive correlation was found between the epicardial temperature and the BST-monitoring value (r = 0.98). In the acute model, all target veins were electrically isolated with BST-controlled ablation at ≥57°C (18/18, 100%). In the chronic model, durable lesions were observed in all veins at 60°C, while 44% of the veins showed reconnection at 57°C. In both pathological analyses, significantly greater lesions were observed at 60°C than at 57°C. There were no significant differences in adverse events between the two groups. CONCLUSION: Balloon surface temperature-controlled ablation at 60°C using the second-generation RHB may be optimal for creating durable lesions without compromising safety.

Efficacy of Low-Dose Isoproterenol Infusion for the Exclusion of a Left Atrial Appendage Thrombus in Patients With Dense Spontaneous Echo Contrast Caused by Atrial Fibrillation.

BACKGROUND: In patients with atrial fibrillation (AF) and severe blood stasis in the left atrial appendage (LAA), dense spontaneous echo contrast (SEC) disturbs the distinct visualization of the LAA interior, thus making thrombus diagnosis inconclusive. We aimed to prospectively assess the efficacy and safety of a protocol for a low-dose isoproterenol (ISP) infusion to reduce SEC to exclude an LAA thrombus.Methods and Results: We enrolled 17 patients with AF and dense SEC (Grade 4 or sludge). ISP was infused with gradually increasing doses of 0.01, 0.02, and 0.03 µg/kg/min at 3-min intervals. After increasing the dose to 0.03 µg/kg/min for 3 min, or when the LAA interior was visible, the infusion was terminated. We reassessed the SEC grade, presence of an LAA thrombus, LAA function, and left ventricular ejection fraction (LVEF) within 1 min of ISP termination. Compared with baseline, ISP significantly increased LAA flow velocity, the LAA emptying fraction, LAA wall velocities, and LVEF (all P<0.01). ISP administration significantly reduced the SEC grade (median) from 4 to 1 (P<0.001). The SEC grade decreased to ≤2 in 15 (88%) patients, and the LAA thrombus was excluded. There were no adverse events. CONCLUSIONS: Low-dose ISP infusion may be effective and safe to reduce SEC and exclude an LAA thrombus by improving LAA function and LVEF.

HotBalloon Pulmonary Vein Isolation Registry Study　- Real-World Efficacy and Safety of HotBalloon Ablation.

BACKGROUND: Radiofrequency hotballoon (RHB) is an ablation device used for atrial fibrillation (AF) treatment. The efficacy and safety of RHB-based pulmonary vein isolation (PVI) in real-world practice are unknown.Methods and Results: A multicenter, prospective registry study (UMIN000029567) enrolled AF patients who underwent RHB-PVI. The primary endpoint was the AF recurrence-free survival rate at 12 months after PVI. Of the 679 patients enrolled, 613 (90.3%; paroxysmal AF, n=370; persistent AF, n=136; long-standing AF, n=107) underwent initial RHB-PVI. Acute isolation using only the RHB was successful for 55.6% of patients and 83.5% of pulmonary veins (PVs). The acute isolation rate was higher for patients with paroxysmal AF and more experienced centers. Antiarrhythmic drugs were prescribed after 3 months for 47.5% of patients. The AF recurrence-free survival rate at 12 months was 83.7%. Procedure-related complications including atrio-esophageal fistula (n=1) and phrenic nerve injury (persistent; n=4, permanent; n=2) were observed in 19 (3.1%) patients. Five (1.7%) of the 302 patients who underwent pre-procedural and post-procedural multidetector computed tomography had severe PV stenosis. CONCLUSIONS: The size-adjustable RHB has been used for the treatment of various AF types. The arrhythmia recurrence-free rate at 12 months, with the use of antiarrhythmic drugs in approximately half of the patients, was acceptable, but the acute isolation rate using the RHB requires further improvement.

Clinical Characteristics of Non-Valvular Atrial Fibrillation Patients With a Large Left Atrial Appendage Ostium-Limiting Percutaneous Closure.

BACKGROUND: The left atrial appendage (LAA) is a therapeutic target for preventing cardioembolic stroke in patients with non-valvular atrial fibrillation (NVAF). A large LAA ostium limits percutaneous LAA closure. This study investigated the characteristics and factors associated with a large LAA ostium in Japanese patients with NVAF.Methods and Results: In 1,102 NVAF patients, the maximum LAA diameter was measured using transesophageal echocardiography (TEE). A large LAA ostium was defined by a maximum diameter of >30 mm. Forty-four participants underwent repeated TEEs, and changes in LAA size under lasting AF were assessed. A large LAA ostium was observed in 3.1% of all participants and 8.9% of patients with long-standing persistent AF (LSAF). The large LAA group had greater CHA2DS2-VASc (P=0.024) and HAS-BLED scores (P=0.046) and a higher prevalence of LAA thrombus (P=0.004) than did the normal LAA group. LSAF, moderate or severe mitral regurgitation, left atrial volume ≥42 mL/m2, E/E' ratio ≥9.5, and left ventricular mass ≥85 mg/m2were independently associated with a large LAA ostium (P<0.001, P<0.001, P=0.009, P=0.009, and P=0.032, respectively). In 44 patients with lasting AF, the LAA ostial diameter increased over time (P<0.001). CONCLUSIONS: NVAF patients with a large LAA ostium may have a higher risk of stroke and bleeding. LSAF and factors leading to LA overload may be closely associated with LAA ostial dilatation and can promote it.

Catheter ablation of ventricular tachycardia in dilated-phase hypertrophic cardiomyopathy: Substrate characterization and ablation outcome.

INTRODUCTION: Catheter ablation is a therapeutic option to suppress ventricular tachycardia (VT) in the setting of dilated-phase hypertrophic cardiomyopathy (DHCM). However, the characteristics of the arrhythmogenic substrate and the ablation outcome are not fully illustrated. METHOD: A total of 23 ablation procedures for drug-refractory sustained monomorphic VTs in 13 DHCM patients (60 ± 11 years, one female, the left ventricular [LV] ejection fraction 39% ± 9%, the LV mass index 156 ± 39 g/m2 ) were performed. The distribution of VT substrate as endocardial or epicardial/intramural was based on detailed mapping and ablation response during VT. RESULT: Two patients underwent ablation of sustained monomorphic VT that was not scar-mediated tachycardia. Of the remaining 11 patients, eight (73%) patients had VT substrate in the basal regions, most frequently at the epicardial and/or intramural basal antero-septum. None of the patients had VT substrate located at the LV inferolateral region. Ablation at the right ventricular septum and the aortic cusps was done in four and five patients, respectively. Other approaches including bipolar and chemical ablations, were done in three and two patients, respectively. Six (55%) out of 11 patients (two patients lost follow-up) had VT recurrence. All the six patients had basal substrate. However, anti-tachycardia pacing was sufficient for VT termination except in one patient. CONCLUSION: Catheter ablation of VT in patients with DHCM is challenging because of the predominant basal anteroseptal epicardial/intramural location of arrhythmogenic substrate. An ablation approach from multiple sites and/or adjunctive interventional techniques are often required.

Preprocedural restoration of sinus rhythm and left atrial strain predict outcomes of catheter ablation for long-standing persistent atrial fibrillation.

INTRODUCTION: Catheter ablation (CA) for long-standing persistent atrial fibrillation (LS-AF) remains challenging. We aimed to explore whether sinus rhythm (SR) restoration and left atrium (LA) function after pretreatment with antiarrhythmic drugs (AAD's) and electrical cardioversion (ECV) predict procedural outcomes. METHODS AND RESULTS: We included 100 consecutive patients with LS-AF who were treated with AAD/ECV for at least 3 months before CA. The echocardiographic LA strain during reservoir phase (LASr) was assessed after pretreatment as a marker of LA fibrosis. The recurrence was recorded for ≥1 year after the last procedure. During a 34 ± 16-month follow-up period, the single and multiple procedures and pharmaceutically assisted success rates were 40% and 71%, respectively. Patients with preprocedural SR restoration and higher LASr showed a significantly higher recurrence-free probability after the last CA (logrank P = .001 and P < .001, respectively). Failure of preprocedural SR restoration and LASr ≤8.6% were independently associated with recurrence after the last CA (hazard ratio [HR]: 3.13, 95% confidence interval [CI]: 1.42-6.91, P = .005; HR: 3.89, 95% CI: 1.65-9.17, P = .002, respectively). These parameters added incrementally to the predictive value of AF duration and LA dilatation (P = .03 and P = .002, respectively) and improved the recurrence-risk stratification (net reclassification improvement = 0.39; 95% CI = 0.13-0.65; P = .003). CONCLUSION: In patients with LS-AF, the inability to restore SR and lower LASr after AAD/ECV treatment independently and incrementally predicts the recurrence after CA. These findings might be useful for determining LS-AF ablation candidates.

Efficacy and Safety of Left Atrial Appendage Closure With WATCHMAN in Japanese Nonvalvular Atrial Fibrillation Patients　- Final 2-Year Follow-up Outcome Data From the SALUTE Trial.

BACKGROUND: The SALUTE trial was a prospective, multicenter, single-arm trial to confirm the safety and efficacy of the WATCHMAN left atrial appendage closure (LAAC) device for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF) in Japan.Methods and Results:A total of 54 subjects (including 12 roll-in subjects) with a WATCHMAN implant procedure were followed in 10 investigational centers. Follow-up visits were performed up to 2 years post-implant. The baseline CHA2DS2-VASc score was 3.6±1.6 and the baseline HAS-BLED score was 3.0±1.1. All 42 subjects in the intention to treat (ITT) cohort underwent successful implantation of the LAAC device without any serious complications, achieving the prespecified performance goal. The effective LAAC rate was maintained at 100% from 45 days to 12 months post-implant, achieving the prespecified performance goal. During follow-up, 1 subject died of heart failure, and 3 had ischemic strokes, but there were no cases of hemorrhagic stroke or systemic embolism. All events were adjudicated as unrelated to the WATCHMAN device/procedure by the independent Clinical Events Committee. All 3 ischemic strokes were classified as nondisabling based on no change in the modified Rankin scale score. CONCLUSIONS: Final results of the SALUTE trial demonstrated that the WATCHMAN LAAC device is an effective and safe alternative nonpharmacological therapy for stroke risk reduction in Japanese NVAF patients who are not optimal candidates for lifelong anticoagulation. (Trial Registration: clinicaltrials.gov Identifier NCT03033134).

Stepwise approach to induce infrequent premature ventricular complex using bolus isoproterenol and epinephrine infusion.

BACKGROUND: Paucity of a premature ventricular complex (PVC) during ablation procedures may occur and be associated with a lower success rate. Isoproterenol (ISP) injections are commonly used to induce PVC; however, the induced tachycardia sometimes prevents the appearance of PVC. Epinephrine (EPI) administration may be an alternative strategy to induce PVC due to its smaller effect on heart rate (HR). This study sought to examine the electrophysiological impact of EPI injection, with a stepwise induction protocol, for infrequent intraprocedural PVC. METHODS: We studied 78 consecutive patients who underwent catheter ablation of idiopathic frequent PVC. If no PVC was observed at the beginning of the procedure, ISP (10 µg) was injected. If clinical PVC was not induced by ISP administration, EPI (10 µg) was injected. RESULTS: Of 18 patients without PVC at baseline, ISP injection induced PVC in five patients. Of the remaining 13 patients, EPI injection successfully induced PVC in seven patients (53%). The maximum HR and increments of HR after EPI injection were significantly lower than those after ISP injection (99 ± 15 vs 137 ± 15 bpm, P = .001; 22 ± 10 vs 53 ± 12 bpm, P < .001, respectively). There were no complications related to the induction protocol. CONCLUSION: EPI injection following ISP injection is an effective and safe stepwise approach for the induction of infrequent PVC in the electrophysiology laboratory. It is hypothesized that α- and ß-adrenergic receptor stimulation by EPI injections, with reduced HR acceleration compared to that with ISP injections, may result in the successful induction of PVC.

Percutaneous WATCHMAN Left Atrial Appendage Closure for Japanese Patients With Nonvalvular Atrial Fibrillation at Increased Risk of Thromboembolism　- First Results From the SALUTE Trial.

BACKGROUND: The PROTECT AF and PREVAIL trials demonstrated that the WATCHMAN left atrial appendage (LAA) closure device is a reasonable alternative to warfarin therapy for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF) in the USA and Europe. We conducted the SALUTE trial to confirm the safety and efficacy of the LAA closure therapy for patients with NVAF in Japan. Methods and Results: A total of 54 subjects (including 12 Roll-in) with NVAF who had a CHA2DS2-VASc score ≥2 were enrolled. All subjects were successfully implanted with the LAA closure device. No serious adverse events related to the primary procedure-safety endpoint occurred. The 2nd co-primary endpoint was a composite of all stroke, systemic embolism and cardiovascular/unexplained death. One ischemic stroke (1/42) occurred during the 6-month follow-up. The effective LAA closure rate defined as the 3rd co-primary endpoint was 100% (42/42) at both 45-day and 6-month follow-up. CONCLUSIONS: The procedural safety and 6-month results from the SALUTE trial demonstrated that the LAA closure device was safe and effective, similar to the results of large-scale randomized clinical trials, and provides a novel perspective of LAA closure for Japanese patients with NVAF in need of an alternative to long-term oral-anticoagulation. (Trial Registration: clinicaltrials.gov Identifier NCT 03033134).

"Pseudo" Hisian extrasystole arising from the proximal portion of the left bundle branch.

The diagnosis of a Hisian extrasystole is based on simple electrocardiographic features and both an extrasystole arising from the His-Bundle ("true" Hisian extrasystole) and also one from the proximal portion of the bundle branch ("pseudo" Hisian extrasystole) would be diagnosed as Hisian extrasystoles [1]. Here we report a case of "pseudo" Hisian extrasystole arising from the proximal portion of the left bundle branch and the successful catheter ablation was achieved in the right coronary cusp.

Unmasking of a concealed slow pathway by atrioventricular simultaneous basic pacing.

A 71-year-old woman with narrow QRS tachycardia was referred for catheter ablation. The clinical tachycardia was diagnosed as slow/fast form of atrioventricular (AV) nodal reentrant tachycardia (AVNRT) with the upper common pathway. Although neither conventional nor double atrial programmed extrastimulation (APS) showed any evidence of a dual AV nodal pathway, AV simultaneous pacing during basic stimulation preceding APS (AVSP-APS) reproducibly revealed a dual AV nodal pathway as a double ventricular response. The AVSP-APS pacing method may be helpful to unmask a "concealed slow pathway" in patients with AVNRT.

Fragmented QRS Is a Novel Risk Factor for Ventricular Arrhythmic Events After Receiving Cardiac Resynchronization Therapy in Nonischemic Cardiomyopathy.

INTRODUCTION: A fragmented QRS (fQRS) is reported to be associated with a poor prognosis or sudden cardiac death (SCD) in patients with Brugada syndrome or ischemic heart disease. However, no studies have clarified the impact of the presence of an fQRS on SCD or ventricular arrhythmic events in patients receiving cardiac resynchronization therapy (CRT). This study aimed to clarify this point in patients with nonischemic cardiomyopathy. METHODS AND RESULTS: This study included 137 heart failure patients with nonischemic cardiomyopathy who received CRT (NYHA functional class: II/III/IV = 25/84/28). The 12-lead ECGs before and after CRT were analyzed. The presence of an fQRS was decided in accordance with the definition in previous papers. Before the CRT, an fQRS was observed in 67 patients (fQRS-pre; 49%). However, it was masked in 35 (52% of fQRS-pre) patients after the CRT. Inversely, in 70 patients in whom an fQRS was absent before the CRT, it appeared after the CRT in 15 (21%) patients. As a result, 47 patients (34%) had an fQRS after the CRT (fQRS-post), and it was less than that before the CRT (P = 0.014). During 18 months of follow-up, SCD or ventricular arrhythmic events were observed more frequently in patients with an fQRS-post than in those without (36.2% vs. 3.3%, P < 0.001). A Cox regression analysis revealed that an fQRS-post was significantly associated with those events (hazard ratio = 9.18; 95% confidence interval = 2.45-34.48, P = 0.001). CONCLUSION: In patients with nonischemic cardiomyopathy who received CRT, an fQRS-post was independently associated with SCD or ventricular arrhythmic events.

Electrophysiological Characteristics and Radiofrequency Catheter Ablation Treatment of Idiopathic Ventricular Arrhythmias Successfully Ablated From the Ostium of the Coronary Sinus.

BACKGROUND: Idiopathic ventricular arrhythmias (VAs) rarely arise from the epicardium at the crux of the heart. However, the electrophysiological characteristics of VAs successfully ablated from the ostium of the coronary sinus (CSO) have not yet been documented.Methods and Results:Electrocardiographic and electrophysiological data were analyzed in patients with idiopathic VAs successfully ablated from the CSO.Among 309 patients with idiopathic VAs treated with radiofrequency catheter ablation (RFCA), 6 (1.94%; 3 men; age: 66.3±9.7 years) had VAs successfully ablated from the CSO. Only 1 patient had sustained ventricular tachycardia. The morphology of the QRS showed a left superior axis and QS pattern in leads III and aVF. Furthermore, the precordial maximum deflection index was >0.55 in all patients and a right bundle branch block pattern was recorded in 5 of 6 patients. All VAs were successfully eliminated by RFCA within the CSO. Intracardiac ECGs at sites where VAs were eliminated by RFCA showed clear atrial and ventricular potentials (atrial amplitude: 0.21±0.11 mV; ventricular amplitude: 0.43±0.24 mV), except in 1 case of atrial fibrillation. No patients had recurrence during the 3.4±1.8-year follow-up period. CONCLUSIONS: The idiopathic VAs in our study were eliminated by RFCA within the CS, where a clear atrial amplitude was recorded.

Efficacy of Intensive Radiofrequency Energy Delivery to the Localized Dense Scar Area in Post-Infarction Ventricular Tachycardia Ablation　- A Comparative Study With Standard Strategy Targeting the Infarcted Border Zone.

BACKGROUND: Several reports have demonstrated the importance of severely low voltage areas as arrhythmogenic substrates of ventricular tachycardia (VT). However, a comparative study of dense scar-targeted and infarcted border zone-targeted strategies has not been reported.Methods and Results:We divided 109 consecutive patients with VT post-infarction from 6 centers into 2 groups according to the ablation strategy used: dense scar-targeted ablation (DS ablation, 48%) or border zone-targeted ablation (BZ ablation, 52%). During DS ablation, we attempted to identify VT isthmuses in the dense scar areas (≤0.6 mV) using detailed pace mapping, and linear ablation lesions were applied mainly to those areas. During BZ ablation, linear ablation of standard low voltage areas (0.5-1.5 mV) was performed along with good pace map sites of the clinical VT. Acute success was defined as complete success (no VTs inducible) or partial success (clinical VT was noninducible). The acute complete success rate was significantly higher for DS ablation than for BZ ablation (62% vs. 42%, P=0.043). During a median follow-up of 37 months, the VT-free survival rate was significantly higher for DS ablation than for BZ ablation (80% vs. 58% at 48 months; log-rank P=0.038). CONCLUSIONS: DS ablation may be a more effective therapy for post-infarction VT than BZ ablation in terms of the acute complete success rate and long-term follow-up.

J Waves Are Associated With the Increased Occurrence of Life-Threatening Ventricular Tachyarrhythmia in Patients With Nonischemic Cardiomyopathy.

INTRODUCTION: Recent studies showed that J waves were associated with higher incidence of ventricular tachyarrhythmia (VT/VF) in patients with idiopathic ventricular fibrillation (VF) and myocardial infarction. We sought to assess the association between J waves and VT/VF in patients with nonischemic cardiomyopathy (NICM). METHODS AND RESULTS: We retrospectively enrolled 109 patients (79 men; mean age, 60 ± 15 years) with NICM who underwent implantable cardioverter defibrillator (ICD) implantation. The primary endpoint of this study was the occurrence of appropriate device therapy due to sustained VT/VF. The J wave was electrocardiographically defined as an elevation of the terminal portion of the QRS complex of >0.1 mV in at least 2 contiguous inferior or lateral leads. Among the 109 patients, 37 (34%) experienced an episode of appropriate device therapy during a median follow-up period of 25.9 (IQR 11.5-54.3) months. Kaplan-Meier curves showed that the presence of J waves on the 12-lead ECG obtained before device implantation was associated with an increased occurrence of appropriate device therapy (P < 0.001). Multivariate Cox proportional regression analysis revealed that the presence of J waves (HR 2.95; 95% CI 1.31-6.64; P = 0.009) was an independent predictor for the occurrence of appropriate device therapy. In the subgroup analysis of the patients with dilated or hypertrophic cardiomyopathy, J wave tended to increase the occurrence of appropriate device therapy (P = 0.056 and P = 0.092, respectively). CONCLUSIONS: The presence of J waves was an independent predictor for the occurrence of appropriate device therapy in patients with NICM who underwent ICD implantation.

Idiopathic Premature Ventricular Contraction Conducting over a Ventricle Myocardial Extension from the Pulmonary Artery.

Ventricle myocardial extensions (VMEs) from the right ventricular outflow tract to the pulmonary artery (PA) serve as arrhythmogenic foci for idiopathic ventricular arrhythmias (VAs). Although an autopsy study revealed the heterogeneity of the VME, only the electrocardiographic features of PA-VAs arising from septal VMEs have been discussed. Here, we describe a case of idiopathic PA-VAs conducting over a VME accompanied by unique ventricle activation patterns, which contributed to the appearance of an S wave in the inferior limb leads despite an arrythmogenic focus in the outflow tract.