Osamu Inaba

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.

Atrial fibrillation type matters: greater infarct volume and worse neurological defects seen in acute cardiogenic cerebral embolism due to persistent or permanent rather than paroxysmal atrial fibrillation

Aims Some studies have shown that the type of atrial fibrillation (AF), whether paroxysmal AF (PAF) or persistent or permanent AF (PeAF), affects the incidence of ischaemic stroke. This study sought to determine the relationship between the AF pattern and the severity and brain volume of infarction in an AF population including transient ischaemic attack (TIA) patients. Methods and results This was a retrospective observational study. We studied 161 consecutive patients who were admitted to our stroke care unit with cardiogenic embolism or TIA related to non-valvular AF (age 79 ± 9.5, 78 females, and 87 PAF patients). We evaluated the differences in severity and infarct volume between the types of AF. Additionally, we divided the patients into three groups according to severe stroke (n = 38), TIA (n = 28), and those who were neither (stroke, n = 95) for the assessment of the predictors of severe stroke and TIA. Persistent or permanent atrial fibrillation patients with acute cardiogenic stroke or TIA had worse peak National Institute of Health Stroke Scale (NIHSS) scores [PAF median 4 (range 3-14), PeAF 17 (5.8-25); P < 0.0001] and worse NIHSS scores at discharge [PAF 2.0 (1-7), PeAF 11 (3-22); P < 0.0001]. Their infarct brain volume assessed by computed tomography or magnetic resonance imaging was also larger [PAF 4.4 (1.1-32) mL, PeAF 64 (6.9-170) mL; P < 0.0001]. Multivariate analysis of severe stroke vs. non-severe stroke patients showed that having PeAF was the only independent predictor of severe stroke [odds ratio (OR) 4.27, 95% confidence interval (CI) 1.91-10.2; P = 0.0003]. Comparison of TIA vs. non-TIA patients showed that PeAF (OR 0.120, 95% CI 0.0230-0.444; P = 0.0008) and anticoagulant use (OR 8.24, 95% CI 2.15-40.8; P = 0.0018) were independent predictors of TIA. Conclusion Cardiogenic emboli due to non-valvular PeAF are associated with a worse acute clinical course and greater volume of infarction than those due to PAF.

Impact of impedance decrease during radiofrequency current application for atrial fibrillation ablation on myocardial lesion and gap formation

The clinical impact of a decrease in impedance during radiofrequency catheter ablation (RFCA) has not been fully clarified. The aim of the study was to analyze the impact of impedance decrease and to determine its optimal cutoff value during RFCA.

A new mapping method to estimate exit sites of ventricular arrhythmias using intracardiac echocardiography and M-mode for catheter ablation

Catheter ablation of premature ventricular complexes (PVCs) has been used as a curative therapy in many cases. Intracardiac ultrasound with a magnetic sensor probe has recently become available for catheter ablation. In this study, we assessed a new mapping method, contraction mapping, for determining the optimal ablation sites using intracardiac ultrasound and M‐mode. This study sought to assess the accuracy of the new mapping method using intracardiac echocardiography.

Clinical and electrophysiological features of respiratory cycle–dependent atrial tachycardia: An analysis of three cases

Introduction Focal atrial tachycardia (AT) accounts for 5%–15% of arrhythmias in adults who undergo electrophysiological study (EPS) for paroxysmal supraventricular tachycardia, and it can be generated by enhanced automaticity, triggered activity, and microreentry. Radiofrequency catheter ablation (RFCA) has been reported as a curative therapy for AT with a high success rate. While almost all instances of AT can be induced by atrial programmed or constant pacing with or without isoproterenol infusion, some ATs with distinct inducibility features have been reported. Swallowing-induced AT is one of the most well-known ATs of unusual presentation. Activation mapping of swallowing-induced AT requires patients to swallow during mapping because it typically cannot be induced by any pacing methods or isoproterenol, and can only be induced by deglutition. RFCA is also effective in eliminating swallowing-induced AT, similar to typical AT. Therefore, understanding how to induce targeted AT is important to the success of RFCA. Another atypical form of AT, respiratory cycle–dependent AT (RCAT), is a rare clinical condition, the mechanism of which has not been clarified. This report describes successful induction and elimination of RCAT in 3 patients in whom different mechanisms underlying the appearance of RCAT were confirmed.

Verapamil-sensitive atrial tachycardia with a slow conduction zone near the noncoronary aortic sinus and His bundle

This report presents a verapamil‐sensitive atrial tachycardia, mid‐atrium septum activating the earliest. Concealed entrainment was obtained at noncoronary aortic sinus (NCS), where the local activation was delayed compared to mid‐septum. The tachycardia was successfully ablated at NCS. The entrance of the slow conduction zone was located at NCS.