Keijiro Nakamura

Combined Dominant Frequency and Complex Fractionated Atrial Electrogram Ablation After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

Atrial substrates with high‐dominant frequency (DF) and complex fractionated atrial electrogram (CFAE) sites have sources maintaining atrial fibrillation (AF) and are potential AF ablation targets. This study aimed to evaluate an approach of circumferential pulmonary vein isolation (PVI) followed by a DF and CFAE site ablation.

Optimal observation time after completion of circumferential pulmonary vein isolation for atrial fibrillation to prevent chronic pulmonary vein reconnections

PURPOSE To identify predictors of chronic pulmonary vein (PV) reconnection (CPVR) after successful circumferential PV isolation (CPVI) for atrial fibrillation (AF). MATERIALS AND METHODS A total of 718 PVs from 181 consecutive AF patients (141 males, median age 61 years, 92 paroxysmal AF) who underwent a second ablation procedure for recurrent AF were retrospectively analyzed. RESULTS During the second procedure, a CPVR was observed in 477 PVs (66.4%) among 169 patients. In a multiple logistic regression analysis, the observation time after the final completion of the PVI (OT-final) was a significant negative predictor (odds ratio 0.980; P<0.001). A receiver operating characteristic analysis demonstrated that the greatest area under the curve was for the OT-final (0.670). At an optimal cutoff of 35 min, the sensitivity and specificity for predicting a CPVR were 66.9% and 60.6%, respectively. By Kaplan Meier analysis, CPVR was more frequent in PVs with an OT-final of <35 min than ≥35 min (log-rank test, P=0.018). In a vessel-by-vessel analysis, the OT-final at all PV sites was a significant negative predictor, while male gender in the right PVs and left-inferior PV, number of RF applications for the ipsilateral CPVI in the right PVs and left-superior PV, and major PV diameter in the left-superior PV were significant positive predictors of a CPVR (all P<0.05). CONCLUSIONS An optimal observation time (≥35 min in this study) to determine whether PVI is successfully completed during the initial CPVI for AF may be needed to prevent a CPVR and subsequent AF recurrence thereafter.

Predictors of asymptomatic cerebral infarction associated with radiofrequency catheter ablation for atrial fibrillation using an irrigated-tip catheter.

AIMS Catheter ablation is a potentially curative treatment for atrial fibrillation (AF). However, complications such as ischaemic stroke are more frequent and more severe compared with ablation procedures for other arrhythmias. Irrigated-tip catheters have been reported to reduce the risk of stroke. The present study aimed to evaluate predictors of asymptomatic cerebral infarction (CI) after AF ablation using an irrigated-tip catheter. METHODS AND RESULTS A total of 70 consecutive AF patients who underwent catheter ablation were subjected to brain magnetic resonance imaging (MRI) 1 day after the procedure. In 10 (14.3%) of 70 patients, MRI revealed acute CI, but neither symptoms nor abnormal neurological findings were present in these patients. In univariate analysis, a history of persistent AF, left atrial dimension, presence of spontaneous echo contrast (SEC), procedure duration prior to heparin injection, and electrical cardioversion during the procedure differed significantly between the two groups, those with and without CI (P = 0.02, 0.05, 0.01, 0.01, and 0.05, respectively). Multivariate logistic regression analysis identified SEC [odds ratio (OR), 9.39; 1.60-55.2; P = 0.01] and procedure duration prior to heparin injection (OR, 1.19; 1.04-1.36; P = 0.01) as predictive of acute asymptomatic CI after AF ablation. CONCLUSION The presence of SEC and procedure duration prior to heparin injection are determinants of asymptomatic CI during AF ablation despite the use of an irrigated-tip catheter.

Outcomes of Brugada Syndrome Patients with Coronary Artery Vasospasm

Objective To evaluate the outcomes of patients with concomitant Brugada syndrome and coronary artery vasospasm. Methods Patients diagnosed with Brugada syndrome with an implantable cardiac defibrillator were retrospectively investigated, and the coexistence of vasospasm was evaluated. The clinical features and outcomes were evaluated, especially in patients with coexistent vasospasm. A provocation test using acetylcholine was performed in patients confirmed to have no organic stenosis on percutaneous coronary angiography to confirm the presence of vasospasm. Implantable cardiac defibrillator shock status was checked every three months. Statistical comparisons of the groups with and without vasospasm were performed. A univariate analysis was also performed, and the odds ratio for the risk of implantable cardiac defibrillator shock was calculated. Patients Thirty-five patients with Brugada syndrome, of whom six had coexistent vasospasm. Results There were no significant differences in the laboratory data, echocardiogram findings, disease, or the history of taking any drugs between patients with and without vasospasm. There were significant differences in the clinical features of Brugada syndrome, i.e. cardiac events such as resuscitation from ventricular fibrillation or appropriate implantable cardiac defibrillator shock. Four patients with vasospasm had cardiac events such as resuscitation from ventricular fibrillation and/or appropriate defibrillator shock; three of them had no cardiac events with calcium channel blocker therapy to prevent vasospasm. The coexistence of vasospasm was a potential risk factor for an appropriate implantable cardiac defibrillator shock (odds ratio: 13.5, confidence interval: 1.572-115.940, p value: 0.035) on a univariate analysis. Conclusion Coronary artery vasospasm could be a risk factor for cardiac events in patients with Brugada syndrome.

Congenital Absence of Left Atrial Appendage Diagnosed by Multimodality Imaging

A 70-years-old male with a history of hypertension and drug resistant paroxysmal atrial fibrillation (AF) presented to our hospital for catheter ablation to his symptomatic AF. He had no prior surgical or percutaneous procedure to close or exclude the left atrial appendage (LAA). A transesophageal echocardiography (TEE) was performed to rule out intra-cardiac thrombus prior to the ablation procedure. Although the TEE imaging at multiple acquisition angles was obtained, the LAA could not be visualized and an absence of the LAA was suspected. An absence of the LAA was confirmed using cardiac computed tomography (CT), which included 3D reconstruction. Additionally, the LAA was not visualized with left atrium (LA) angiography. During the ablation procedure, 3D voltage mapping in LA was created and no low voltage area or abnormal potential was recorded around the usual root location of the LAA. Successful electrical pulmonary vein isolation was achieved with no major complications. After six months of follow-up, the patient remained in sinus rhythm without any antiarrhythmic drugs and showed no related clinical symptoms. He stopped his anticoagulation therapy due to lack of evidence of AF recurrence and an absence of LAA. Multimodality imaging allowed us to identify the congenital absence of LAA.

Leadless Pacemaker and Subcutaneous Implantable Cardioverter Defibrillator Combination in a Hemodialysis Patient

Received March 2, 2018; revised manuscript received April 25, 2018; accepted May 7, 2018; released online June 6, 2018 Time for primary review: 12 days Division of Cardiovascular Medicine, Toho University Ohashi Medical Center, Tokyo (Y.E., H.H., R.I., S.T., K.N., M.M., M. Nakamura); Division of Cardiovascular Center, Toho University Sakura Medical Center, Sakura (M. Noro); and Division of Cardiology, Odawara Cardiovascular Hospital, Odawara (K.S.), Japan Mailing address: Yoshinari Enomoto, MD, Division of Cardiovascular Medicine, Toho University Ohashi Medical Center, 2-17-6 Ohashi Meguro-ku, Tokyo 153-8515, Japan. E-mail: yenomo1225@oha.toho-u.ac.jp ISSN-1346-9843 All rights are reserved to the Japanese Circulation Society. For permissions, please e-mail: cj@j-circ.or.jp Leadless Pacemaker and Subcutaneous Implantable Cardioverter Defibrillator Combination in a Hemodialysis Patient

A potential pitfall of the modified 12 lead electrocardiogram (Mason–Likar modification) in catheter ablation of idiopathic ventricular arrhythmias originating from the outflow tract

AIMS The Mason-Likar modified electrocardiogram (ML-ECG) can be interchanged with standard 12 lead ECG electrode positions (standard ECG) without affecting the diagnostic interpretation during sinus rhythm, but the morphological differences during ventricular arrhythmias have not been sufficiently evaluated. This study aimed to elucidate the morphological changes in the ML-ECG precordial leads. METHODS AND RESULTS In 53 consecutive patients with premature ventricular contractions predicted to originate from the outflow tract (OT-PVCs), the arrhythmias were analysed by those two ECG methods. The OT-PVC origin sites, which were predicted by currently published criteria with the respective ECG methods prior to catheter ablation, were compared with the successful ablation sites. Compared with the standard-ECG, S-waves in the ML-ECG became shallower in leads V1-4 (P < 0.05 in lead V1; P < 0.001 in leads V2-4), and pseudo-R-waves in lead V1 appeared in seven patients. The precordial leads transition zone shifted counter-clockwise in 18 patients in the ML-ECG. In leads I and aVL, the negative deflection amplitudes of the ML-ECG were greater than those of the standard ECG (P < 0.001), and polarity reversals in lead I appeared in 18 patients. The R-wave amplitudes in all ML-ECG inferior leads were greater than those in the standard-ECG leads (all for P < 0.001). Those changes had an effect on the diagnostic indexes for the localization, and the specificity of the criteria for the ML-ECG was poorer than that for the standard-ECG. CONCLUSION Great differences were found between those two ECG methods. Predicting OT-PVC origins by diagnostic criteria with the ML-ECG might result in a misdiagnosis and inefficient ablation.

Atrial Tachyarrhythmias Concomitant with Perimitral Atrial Flutter during Catheter Ablation

Background: We report 3 cases demonstrating transition from perimitral atrial flutter to a different atrial tachycardia/flutter (AT/AFL) during linear ablation between the left pulmonary vein (PV) and the mitral annulus (mitral isthmus ablation). Methods: N/A. Results: A 67-year-old man with prior pulmonary vein isolation (PVI) underwent RFCA for recurrent AFL. Electrophysiological study (EPS) initially revealed clockwise perimitral AFL. During mitral isthmus ablation, the AFL changed into a focal AT from left atrial (LA) inferior wall with change in cycle length (CL) from 230 ms to 310 ms, which was successfully ablated at the earliest atrial activation site. A 70-year-old woman with prior mitral valve replacement and atrial fibrillation (AF) underwent RFCA for persistent AFL. EPS revealed clockwise perimitral AFL (CL=270 ms). During mitral isthmus ablation, the AFL changed into common AFL without change in CL, thus the two AFLs formed a dual-loop reentry circuit over both atria. A 65-year-old woman with prior PVI underwent RFCA for recurrent AFL. EPS revealed counterclockwise perimitral AFL. During mitral isthmus ablation, the AFL changed into a LA roof dependent AFL with change in CL from 205 ms to 250 ms, which was successfully terminated by LA roof linear ablation. Conclusion: Perimitral AFL can occur simultaneously with another AT/AFL, which becomes apparent with termination of perimitral AFL.

Characteristics of Patients with Direct Conversion of Atrial Fibrillation to Sinus Rhythm or Cavotricuspid-Isthmus Dependent Atrial Flutter by Catheter Ablation

Background: Procedural termination of atrial fibrillation (AF) may be associated with a good long-term outcome in patients with persistent AF. Objective: To determine the characteristics of the patients who converted from AF to sinus rhythm (SR) or cavotricuspid-isthmus dependent atrial flutter (CTI-AFL) without transition to organized left atrial (LA) tachyarrhythmias during ablation. Methods and Results: Thirty-two consecutive patients (26 males, 60±10 years) with AF which lasted more than 3 months when undergoing a first ablation procedure were retrospectively studied. Sixty-eight percent of the patients had AF refractory to amiodarone or bepridil. Pulmonary vein (PV) isolation was initially performed, followed by linear ablation and complex-fractionated electrogram ablation until AF termination. The mean AF duration was 6.7±6.7 months (3–33). During ablation, 26 patients (81%) converted to SR and 6 (19%) to CTI-AFL. The AF termination sites were identified around the PVs (n=21), at the LA anterior septum (n=5), mitral annulus (n=3), LA roof (n=2), and the right atrium (n=1). The mean LA diameter was 42±5 mm and 84% of the patients had LA diameter <45 mm. Conclusion: The preferential AF termination site was around the PVs, followed by at the LA anterior septum. The majority of the patients with AF termination had normal to mild LA dilatation.

Validation of Irrigated Ablation for Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation

Background: Irrigation catheter (Ir–C) is in the process of spreading, however, various aspects of efficient and safe usage are well-known. Methods: Consecutive 122 patients with drug-resistant, paroxysmal atrial fibrillation who underwent extensive pulmonary vein isolation (PVI) using Ir–C were analyzed. PVI were performed with irrigated radiofrequency energy, maximum temperature of 42 °C, power of 25–35 W with constant 17–30 ml/min saline infusion. Right-sided and left-sided circular lesions on left atrial antrum encircling the ipsilateral PVs were placed, guided by 3-dimensional mapping and double Lasso technique. Results: PVI was achieved in all patients, and no major complications related to Ir–C usage were observed. During one application, mean impedance decrease was 13±6 ohm. In the cases with mean time of less than 40 sec for one application (34.9±3.8 sec, n=71), compared with cases with mean time of more than 40 sec for one application (43.1±2.7 sec, n=51), the number of applications was large (58±14 vs. 48±14, p<0.001), procedure time was longer (69±31 vs. 58±22 min, p<0.05), and fluoroscopic time was longer (37±15 vs. 32±11 min, p<0.05). Conclusions: Ir–C was effective and safety for PVI. Applications within mean time of 40 sec might need additional applications, and consequently increased procedure time and fluoroscopic time.