Mihoko Kawabata

Clinical implications of reconnection between the left atrium and isolated pulmonary veins provoked by adenosine triphosphate after extensive encircling pulmonary vein isolation.

Introduction: Dormant pulmonary vein (PV) conduction can be provoked by adenosine triphosphate (ATP) after extensive encircling pulmonary vein isolation (EEPVI). However, the clinical implication of reconnection between the left atrium (LA) and isolated PVs provoked by ATP (ATP‐reconnection) remains unknown.

Right and left ventricular activation sequence in patients with heart failure and right bundle branch block: a detailed analysis using three-dimensional non-fluoroscopic electroanatomic mapping system.

Introduction: Recently, right bundle branch block (RBBB) was proved to be an important predictor of mortality in heart failure (HF) patients as much as left bundle branch block (LBBB). We characterized endocardial right ventricular (RV) and left ventricular (LV) activation sequence in HF patients with RBBB using a three‐dimensional non‐fluoroscopic electroanatomic contact mapping system (3D‐Map) in order to provide the electrophysiological background to understand whether these patients can benefit from cardiac resynchronization therapy (CRT).

Clinical Study Regarding the Anatomical Structures of the Right Atrial Isthmus Using Intra-Cardiac Echocardiography: Implication for Catheter Ablation of Common Atrial Flutter

Background: The construction of complete bi-directional block in the isthmus (ITH) between the tricuspid annulus and inferior vena cava by radiofrequency energy (RF) applications is sometimes hampered due to anatomical problems such as a thick isthmus or aneurysmal pouch in patients with common atrial flutter (AFL).Methods and Results: Fifteen patients were referred for RF ablation of AFL. The anatomical thickness of the right atrial ITH, diameter of the right atrium and thickness of the right atrial free wall were determined using intracardiac echocardiography (ICE), along with the endocardial electrogram recordings at the ITH. RF was applied at the ITH to create a transmural incision to treat the AFL. A significant parallel relationship between the maximum amplitude of the atrial electrogram and the thickness of the ITH, was observed. When the maximum amplitude of the atrial electrogram at the ITH exceeded 1.5 mV, the thickness at the ITH was approximately larger than 5 mm.Conclusions: Using ICE, the precise measurement of the anatomical structures in the heart, including the ITH, was feasible. From the amplitude of the atrial electrogram, a deduction of the thickness at the ITH was possible, which is indispensable information for the appropriate selection of the RF devices.

Torsades de pointes related to transient marked QT prolongation following successful emergent percutaneous coronary intervention for acute coronary syndrome

We report 2 patients in whom transient marked QT prolongation occurred after successful emergent percutaneous coronary intervention (PCI) for acute coronary syndrome. One patient developed torsades de pointes. In both cases, the QT interval became markedly prolonged within 24 hours after PCI, and this prolongation persisted for 4 days. The T waves had a giant and bizarre negative shape with a prolonged T-wave peak to T-wave end interval. No new-onset ischemia or congenital long QT syndrome was related to the episodes. The patients had not taken any drugs that could have prolonged the QT interval, and their serum potassium levels were within normal limits. Torsades de pointes following successful PCI for acute coronary syndrome is uncommon, but acquired long QT syndrome should be considered and treated in patients in whom giant and bizarre negative T waves and QT prolongation develop after PCI.

Discrete Prepotential as an Indicator of Successful Ablation in Patients With Coronary Cusp Ventricular Arrhythmia

Background— Although coronary cusp (CC) ventricular arrhythmia (VA) can be treated by catheter ablation, reliable indicators of successful ablation sites have not been fully identified. Methods and Results— This study comprised 392 patients undergoing radiofrequency catheter ablation for outflow tract-VA at 3 institutions from January 2007 to August 2012. The successful ablation site was on the left CC or right CC in 35 (8.9%) of the 392 patients. In 9 (26%) of these 35 patients, a discrete prepotential was recognized, 5 of whom had left CC-VAs and 4 of whom had right CC-VAs. Radiofrequency catheter ablation was successful at the site of the prepotential in all 9 of these patients. The duration of the isoelectric line between the end of the discrete prepotential and the onset of the ventricular electrogram was 27±13 ms. The time from onset of the discrete prepotential at the successful ablation site on the CC to the QRS onset (activation time) was 69±20 ms (range, 50–98 ms). Pace mapping was graded as excellent at the successful ablation site in only 1 patient. No discrete prepotential was recorded in any successful right outflow tract-VA ablation case in this study. Conclusions— A discrete prepotential was seen in 9 (26%) of 35 patients with CC-VA. In left and right CC-VA, the site of a discrete prepotential with ≥50 ms activation time may indicate a successful ablation site.

Discrete Pre-Potential as an Indicator of Successful Ablation in Patients with Coronary Cusp Ventricular Arrhythmia

Background— Although coronary cusp (CC) ventricular arrhythmia (VA) can be treated by catheter ablation, reliable indicators of successful ablation sites have not been fully identified. Methods and Results— This study comprised 392 patients undergoing radiofrequency catheter ablation for outflow tract-VA at 3 institutions from January 2007 to August 2012. The successful ablation site was on the left CC or right CC in 35 (8.9%) of the 392 patients. In 9 (26%) of these 35 patients, a discrete prepotential was recognized, 5 of whom had left CC-VAs and 4 of whom had right CC-VAs. Radiofrequency catheter ablation was successful at the site of the prepotential in all 9 of these patients. The duration of the isoelectric line between the end of the discrete prepotential and the onset of the ventricular electrogram was 27±13 ms. The time from onset of the discrete prepotential at the successful ablation site on the CC to the QRS onset (activation time) was 69±20 ms (range, 50–98 ms). Pace mapping was graded as excellent at the successful ablation site in only 1 patient. No discrete prepotential was recorded in any successful right outflow tract-VA ablation case in this study. Conclusions— A discrete prepotential was seen in 9 (26%) of 35 patients with CC-VA. In left and right CC-VA, the site of a discrete prepotential with ≥50 ms activation time may indicate a successful ablation site.

Bleeding events and activated partial thromboplastin time with dabigatran in clinical practice

BACKGROUND Dabigatran has demonstrated promising results for the prevention of strokes in patients with non-valvular atrial fibrillation (NVAF). However, there have been episodes of major bleeding, especially in elderly patients or those with renal dysfunction. The purpose of this study was to retrospectively examine the relationship between the bleeding events and activated partial thromboplastin time (APTT) values under dabigatran usage in the everyday clinical practice. Moreover, we investigated which factors would contribute to the APTT values. METHODS AND RESULTS A total of 139 NVAF patients (112 men, 65 ± 11 years) were included. We evaluated the influence of the putative etiological variables and the bleeding score, HAS-BLED score, on APTT values: age greater than 70 years, renal function, gender, dose of dabigatran, and the concomitant prescription of a P-glycoprotein inhibitor. There were 50 patients with an age of ≥ 70 years (36.0%). A P-glycoprotein inhibitor was administered in 18 patients. During the observation period (median 120 days) there was 1 episode of asymptomatic cerebral infarction. There were no intrinsic major bleeding events, however, 11 patients had minor hemorrhagic events. The results of the APTT measurements exhibited a variety of values both among inter- and intra-individuals. On multivariable analysis, significant associations were found between the following risk factors and the APTT values: creatinine clearance, dose of dabigatran, and concomitant use of a P-glycoprotein inhibitor. The minor bleeding events did not correlate with the APTT values, nor HAS-BLED score. CONCLUSIONS The APTT values became prolonged under dabigatran usage and exhibited a remarkable diversity. Although major bleeding did not occur unless APTT was prolonged excessively, minor bleeding arose irrespective of the APTT values even within the range of the APTT values not exceeding 80s.

Clinical and electrophysiological characteristics of patients having atrial flutter with 1:1 atrioventricular conduction

AIMS The purpose of this retrospective study was to assess characteristics of patients who had suffered atrial flutter (AFL) with 1:1 atrioventricular (AV) conduction (1:1 AFL). METHODS AND RESULTS Subjects were 8 patients (61 +/- 14 years) with documented 1:1 AFL, and 101 AFL patients without a history of 1:1 AFL (control patients). 1:1 AFL occurred during physical activity with a ventricular rate of 218 +/- 18 bpm. Antiarrhythmic agents were administered to all eight 1:1 AFL patients, whereas AV nodal conduction-suppressing agents were administered to four. The maximum ventricular rate at which 1:1 AV conduction occurred was significantly lower than when spontaneous 1:1 AFL occurred (164 vs. 218 bpm, P < 0.05). The 1:1 AFL patients had a significantly longer AFL cycle length (CL) (292 vs. 258 ms, P < 0.05) and more rapid AV nodal conduction time (maximum 1:1 AV conduction: 375 vs. 464 ms, P < 0.05) than did control. Arrhythmia had occurred in patients with an AFL CL > or = 250 ms and a CL of maximum 1:1 AV conduction < or = 400 ms. CONCLUSION Clinicians should be aware of the potential for 1:1 AV conduction in AFL patients, especially in those with remarkable prolongation of the CL in addition to enhanced AV conduction.

Role of oral amiodarone in patients with atrial fibrillation and congestive heart failure

BACKGROUND Amiodarone is recognized as the most effective therapy for maintaining sinus rhythm (SR) post cardioversion in patients with atrial fibrillation (AF). It is also recommended for controlling AF in patients with congestive heart failure (CHF). We retrospectively examined the efficacy and safety of oral amiodarone in patients with AF and CHF. METHODS Forty-eight consecutive AF patients whose left ventricular ejection fraction (LVEF) was less than 50% and B-type natriuretic peptide (BNP) was higher than 100 pg/ml were investigated retrospectively, and divided into 3 groups: paroxysmal AF, 16 patients; persistent AF, 9 patients; and permanent AF, 23 patients. RESULTS The permanent AF group had a longer history of AF, larger left ventricular end-diastolic diameter (LVDd) and left atrial diameter (LAD) than paroxysmal and persistent AF groups (p<0.05). After median follow-up of 265 days, amiodarone suppressed paroxysms in 88% of paroxysmal AF patients, while SR was maintained in all persistent AF patients, and 35% of permanent AF patients. Of the 32 persistent and permanent AF patients, 12 (71%) out of 17 maintained SR after successful electrical cardioversion, and conversion to SR occurred spontaneously in 5 (33%) out of 15. The effective group had significantly smaller LVDd and LAD than the ineffective group. In the effective group, BNP decreased significantly from 723±566 pg/ml to 248±252 pg/ml, (p<0.0005) and LVEF increased significantly from 33±7% to 50±13% (p<0.0005) during follow up, while no changes were observed in the ineffective group. The patients with low LVEF (≤30%) benefited comparably from amiodarone to the patients with LVEF >30%. Complications occurred in 24 (50%) patients leading to discontinuation of amiodarone in 11 (23%). CONCLUSIONS Oral amiodarone helped restore SR in paroxysmal and persistent AF patients with CHF. The successful rhythm control by amiodarone resulted in the improvement of LV function and the decrease of BNP levels.

Utility of Distinctive Local Electrogram Pattern and Aortographic Anatomical Position in Catheter Manipulation at Coronary Cusps

Distinctive Electrogram and Aortography of Coronary Cusp. Background: The coronary cusps have recently become target sites for radiofrequency catheter ablation of both outflow tract ventricular arrhythmias originating near the coronary cusps (CC‐VA) and atrial tachyarrhythmias such as focal atrial tachycardia originating near the noncoronary cusp (NCC‐AT). However, the relation between local electrograms recorded at each CC during sinus rhythm and their anatomical position as assessed by aortography has not yet been systematically described.