Sugako Ishigaki

Gender Differences of Electrophysiological Characteristics in Focal Atrial Tachycardia

Gender differences of supraventricular tachycardias such as atrioventricular nodal re-entry, atrioventricular re-entry, and atrial fibrillation have been reported. There is little evidence of the effect of gender on focal atrial tachycardia (FAT). The study consisted of 298 patients who were referred to this institution for radiofrequency catheter ablation of FAT from October 1992 to April 2008 and included 156 men (52%) and 142 women (48%). Men were significantly older than women (57.9 +/- 18.2 vs 47.2 +/- 19.0 years old, p <0.001). Women had more associated arrhythmias (17.0% vs 28.9%, p = 0.01), mostly due to an increased incidence of atrioventricular nodal re-entrant tachycardia. Men had more cardiovascular co-morbidities (19.9% vs 9.9%, p = 0.02), a mechanism of increased automaticity (19.1% vs 8.1%, p = 0.01), and nonparoxysmal tachycardia (14.7% vs 4.4%, p = 0.01). No gender differences were noted among FAT number, left atrial involvement, shortest tachycardia cycle, success rate of catheter ablation, or recurrence rate of FAT. Mean duration of follow-up was 63.2 +/- 47.5 months. Premenopausal women had a lesser cardiovascular co-morbidity (15.3% vs 4.3%, p = 0.04) and a greater incidence of a mechanism of increased automaticity (13.4% vs 2.9%, p = 0.03). In conclusion, gender differences in electrophysiologic characteristics were noted in FAT.

Electrophysiologic characteristics and catheter ablation of focal atrial tachycardia with more than one focus

BACKGROUND Information about the electrophysiologic characteristics and long-term outcome of catheter ablation in patients with multiple focal atrial tachycardia (AT) is limited. OBJECTIVE The purpose of this study was to investigate the electrophysiologic characteristics and long-term outcome of catheter ablation in patients with multiple focal AT. METHODS Two hundred fifty-one patients who were referred for radiofrequency catheter ablation of focal AT were included for analysis. RESULTS Forty-four patients who had focal AT with more than one focus were identified. Comparing focal AT with a single focus to that with more than one focus, the existence of a left atrial focus, cardiovascular comorbidity, nonparoxysmal tachycardia, shortest tachycardia cycle length, success rate of the ablation, and procedure time all differed. Multivariate logistic analysis revealed that a left atrial focus, cardiovascular comorbidity, and shortest tachycardia cycle length were independent predictors of focal AT with more than one focus. Noncontact mapping of the right atrium revealed larger low-voltage zone and longer total activation time for focal AT with more than one focus. Patients who had focal AT with more than one focus and a failed ablation had a greater number of focal ATs and mechanisms of nonparoxysmal tachycardia. Multivariate logistic analysis revealed that only the number of focal ATs predicted a failed ablation. CONCLUSION Focal ATs with more than one focus have different electrophysiologic characteristics. This study provides new insight into the development and atrial remodeling of focal AT with multiple foci.

Role of the right atrial substrate in different types of atrial arrhythmias

BACKGROUND The regional distribution of the low-voltage zones (LVZs) may relate to the maintenance of atrial arrhythmias in the right atrium (RA). OBJECTIVES The purpose of this study was to investigate the RA substrate characteristics in different types of atrial arrhythmias originating from RA and left atrium (LA). METHODS Forty-five patients (35 men, age = 62 +/- 15 years) with RA atypical atrial flutter (n = 15, group 1), RA atrial fibrillation (AF; n = 15, no PV initiating foci, group 2), and LA AF (n = 1 5, no RA arrhythmias, group 3) referred for three-dimensional EnSite mapping were included. Voltage and activation maps were visualized. RESULTS The mean voltage of the RA was lower in group 2, and compared with group 3, a voltage reduction during atrial pacing was evident in groups 1 and 2. The fixed LVZs (independent of the rhythm) were mostly located along the lower crista terminalis (CT). A functional extension of the LVZ was located on the CT in 84% of patients, sinus venosa in 18%, and free-wall region in 27%, forming the borders of the slow conduction isthmus for the reentrant circuits. The number of slow conduction isthmuses was 1.3 +/- 0.9, 2.2 +/- 1.0, and 0.87 +/- 0.74, for the groups 1-3 patients, respectively (P <.05). Radiofrequency ablation connecting the LVZs successfully eliminated those isthmuses. The long-term follow-up revealed that 66% of the patients remained in sinus rhythm. CONCLUSIONS Single and multiple slow conduction isthmuses bordered by the fixed and functional LVZs were critical for the reentrant circuits in the RA. The conduction isthmuses could be identified by their substrate characteristics and ablated successfully.

Effective prediction of response to cardiac resynchronization therapy using a novel program of gated myocardial perfusion single photon emission computed tomography

AIMS The limitation of QRS duration as a surrogate measure for left ventricular (LV) mechanical dyssynchrony (LVMD) in cardiac resynchronization therapy (CRT) patient selection encourages seeking alternatives to QRS duration. Exploring the potential of an analysis program of electrocardiographically gated myocardial perfusion single photon emission computed tomography (SPECT) (GMPS) for the estimation of LVMD to predict CRT response. METHODS AND RESULTS Twenty-four patients undergoing CRT for advanced heart failure caused by non-ischaemic cardiomyopathy were studied. Gated myocardial perfusion single photon emission computed tomographies were performed in the setting of temporary CRT suspension after 1 week of CRT adoption. The GMPS data were computed with a novel program capable of segmental LV time-volume analysis. When a brain natriuretic peptide (BNP) value decreased >50% at 6-month follow-up, the patient was defined as a CRT responder. Receiver operating characteristic (ROC) curves for identification of responders were analysed for standard deviation of time to end systole (TES-SD) among 17 LV segments. Linear regression analyses demonstrated that an increase in percentage reduction in BNP level at 6-month follow-up was predicted by an increase in TES-SD (R(2) = 0.21, P = 0.023). The TES-SD in responders (n = 15, 62.5%) was higher than that in non-responders (100 ± 51 vs. 41 ± 17 ms, P = 0.0008). A cutoff value of TES-SD >49 ms predicted responders with 100% sensitivity and 78.8% specificity and the area under the ROC curve was 0.881 for TES-SD (P = 0.002). CONCLUSIONS The estimation of LVMD using this novel GMPS program could be an alternative or a complementary approach to QRS duration in CRT patient selection. This finding warrants further assessment of our approach in larger studies.

Modification of Electrophysiological Properties of Pulmonary Veins and Adjacent Left Atrial Tissue by Radiofrequency Thermal Balloon Circumferential Ablation around the Pulmonary Vein Ostia: Correlation with Non-recurrence of Atrial Fibrillation

Objective: The purpose of this study was to provide detailed information as to the modification of electrophysiological properties of pulmonary veins (PVs) and adjacent left atrial (LA) tissue caused by circumferential ablation (ABL) of superior and inferior pulmonary vein ostia using a novel radio‐frequency balloon catheter (RBC), and to correlate such changes with recurrence or non‐recurrence of atrial fibrillation (AF).