Michifumi Tokuda

Reduction of AF recurrence after pulmonary vein isolation by eliminating ATP-induced transient venous re-conduction.

Background: Recent evidence has suggested that the transient re‐conduction of the isolated pulmonary vein (PV) induced by the intravenous injection of adenosine (dormant PV conduction) might predict the incidence of subsequent venous reconnection after the procedure, which is the main cause of the atrial fibrillation (AF) recurrence after PV isolation (PVI). We tested the hypothesis that the elimination of these dormant PV conductions by additional radiofrequency (RF) applications can improve the efficacy of the PVI.

Completion of mitral isthmus ablation using a steerable sheath: prospective randomized comparison with a nonsteerable sheath.

Completion of Mitral Isthmus Ablation. Background: Although mitral isthmus (MI) ablation in atrial fibrillation (AF) patients has been shown to be an effective ablative strategy, the establishment of the bidirectional conduction block of the MI is technically challenging. We investigated the usefulness of a steerable sheath for MI ablation in patients with persistent AF and its impact on the clinical outcome of persistent AF ablation.

Comparison of the clinical outcome after pulmonary vein isolation based on the appearance of adenosine-induced dormant pulmonary vein conduction.

BACKGROUNDnThe elimination of transient pulmonary vein (PV) reconduction (dormant PV conduction) revealed by adenosine in addition to PV isolation reduced the atrial fibrillation (AF) recurrence after catheter ablation. The dormant PV conduction is induced in approximately half of the AF patients that undergo PV isolation. The present study compared the clinical outcome of AF ablation in patients whose dormant PV conduction was eliminated by additional radiofrequency applications with the outcome in patients without dormant conduction.nnnMETHODSnA total of 233 consecutive patients (206 male, 54.2 +/- 10.1 years) that underwent AF ablation were included in the present study. Dormant PV conduction was induced by the administration of adenosine triphosphate after PV isolation and was eliminated by supplemental radiofrequency application. All patients were followed up for >12 months (mean 903 days) after the first ablation.nnnRESULTSnFollowing PV isolation, dormant PV conduction was induced in 139 (59.7%) of 233 patients and was successfully eliminated in 98% (223/228) of those in the first ablation procedure. After the first procedure, 63.9% (149/233) of patients were free from AF recurrence events. The success rates of a single or final AF ablation in patients with the appearance of the dormant PV conduction were similar to those of patients without dormant conduction (P = .69 and P = .69, respectively).nnnCONCLUSIONSnDormant PV conduction was induced in over half of the patients with AF. After the elimination of adenosine triphosphate-induced reconnection, the clinical outcome of patients with the dormant PV conduction was equivalent to that of patients without conduction.

Dormant pulmonary vein conduction induced by adenosine in patients with atrial fibrillation who underwent catheter ablation

BACKGROUNDnintravenous administration of adenosine triphosphate (ATP) is used to induce transient pulmonary vein (PV) reconduction (dormant PV conduction) following PV isolation. This study investigated the detailed characteristics of dormant PV conduction in patients with atrial fibrillation (AF) who underwent catheter ablation.nnnMETHODSntwo hundred sixty consecutive patients (235 men; mean age, 54 ± 10 years) who underwent catheter ablation of their AF were included in this study. ATP was injected following PV isolation to induce dormant PV conduction, which was then eliminated by radiofrequency application.nnnRESULTSndormant PV conduction was induced by ATP in 60.4% (157/260) of the patients and in 25.3% (258/1,021) of the isolated PVs. This transient PV reconduction was more frequently observed in the left superior PV in comparison with other PVs (P < .0001). There was no significant difference in the prevalence of the dormant PV conduction among patients with paroxysmal AF, persistent AF, and long-lasting AF (62%, 66%, and 48%, respectively; P = .13). During the follow-up period, repeat AF ablation was performed in 70 patients with recurrent AF. The dormant PV conduction was less frequently induced in the repeat procedure than in the initial procedure (60.4% vs 31.4%, P < .0001).nnnCONCLUSIONSndormant PV conduction was evenly induced among AF types. The repeat PV isolation led to the decrease in incidence of the ATP-induced acute transient pharmacological PV reconduction.

The role of successful catheter ablation in patients with paroxysmal atrial fibrillation and prolonged sinus pauses: outcome during a 5-year follow-up

AIMSnAlthough patients with paroxysmal atrial fibrillation (AF) and prolonged sinus pauses [tachycardia-bradycardia syndrome (TBS)] are generally treated by permanent pacemaker, catheter ablation has been reported to be a curative therapy for TBS without pacemaker implantation. The purpose of this study was to define the potential role of successful ablation in patients with TBS.nnnMETHODS AND RESULTSnOf 280 paroxysmal AF patients undergoing ablation, 37 TBS patients with both AF and symptomatic sinus pauses (age: 62 ± 8 years; mean maximum pauses: 6 ± 2 s) were analysed. During the 5.8 ± 1.2 years (range: 5-8.7 years) follow-up, both tachyarrhythmia and bradycardia were eliminated by a single procedure in 19 of 37 (51%) patients. Repeat procedures were performed in 14 of 18 patients with tachyarrhythmia recurrence (second: 12 and third: 2 patients). During the repeat procedure, 79% (45 of 57) of previously isolated pulmonary veins (PVs) were reconnected to the left atrium. Pulmonary vein tachycardia initiating the AF was found in 46% (17 of 37) and 43% (6 of 14) of patients during the initial and second procedure, respectively. Finally, 32 (86%) patients remained free from AF after the last procedure. Three patients (8%) required pacemaker implantation, one for the gradual progression of sinus dysfunction during a period of 6.5 years and the others for recurrence of TBS 3.5 and 5.5 years after ablation, respectively.nnnCONCLUSIONnCatheter ablation can eliminate both AF and prolonged sinus pauses in the majority of TBS patients. Nevertheless, such patients should be continuously followed-up, because gradual progression of sinus node dysfunction can occur after a long period of time.

Prospective randomized comparison of a steerable versus a non-steerable sheath for typical atrial flutter ablation

AIMSnAlthough cavotricuspid isthmus (CTI) ablation can cure typical atrial flutter (AFL), it might be difficult to achieve a bidirectional conduction block in the isthmus in some patients. We investigated the usefulness of a steerable sheath for CTI ablation in patients with typical AFL or atrial fibrillation.nnnMETHODS AND RESULTSnA total of 40 consecutive patients (36 males; mean age 55.2 +/- 10.0 years) undergoing CTI ablation were randomized to one of the following two groups: group S (using a steerable long sheath) or group NS (using a non-steerable long sheath). Ablation was performed using an 8 mm tip catheter. The anatomy of the CTI was evaluated by a dual-source computed tomography scan prior to the procedure. The procedural endpoint was the achievement of a bidirectional isthmus conduction block. Bidirectional block in the CTI was achieved in all patients with 485.3 +/- 416.4 s of radiofrequency (RF) application. The CTI anatomy, including the length, depth, and morphology, was similar between the two groups. The duration and total amount of RF energy delivery were significantly shorter and smaller in group S than in group NS (310 +/- 193 vs. 661 +/- 504 s, P = 0.006, and 12,197 +/- 7306 vs. 26,906 +/- 21,238 J, P = 0.006, respectively).nnnCONCLUSIONnThe use of a steerable sheath reduced the time and amount of energy needed to achieve a bidirectional conduction block in the CTI. For patients in whom the establishment of a conduction block is difficult, a steerable sheath should be considered as a therapeutic option for typical AFL ablation.

Substrate Modification by Pulmonary Vein Isolation and Left Atrial Linear Ablation in Patients with Persistent Atrial Fibrillation: Its Impact on Complex‐Fractionated Atrial Electrograms

PV and Linear Ablation for CFAEs.u2002Introduction: Linear ablations in the left atrium (LA), in addition to pulmonary vein (PV) isolation, have been demonstrated to be an effective ablation strategy in patients with persistent atrial fibrillation (PsAF). This study investigated the impact of LA linear ablation on the complex‐fractionated atrial electrograms (CFAEs) of PsAF patients.

Impact of pulmonary vein isolation on the autonomic modulation in patients with paroxysmal atrial fibrillation and prolonged sinus pauses

AIMSnThe efficacy of catheter-based pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) and prolonged sinus pauses [bradycardia-tachycardia syndrome (BTS)] has been already described. However, the effects of PVI on autonomic modulation in BTS patients remain to be determined. We, therefore, examined the alteration in the autonomic modulation through the PVI procedure by using a heart rate variability (HRV) analysis of 24 h ambulatory monitoring.nnnMETHODS AND RESULTSnThis study consisted of 26 symptomatic paroxysmal AF patients either with prolonged sinus pauses on termination of AF (>3.0 s, BTS group, n = 11) or without any evidence of sinus node dysfunction (control group, matched for sex and age, n = 15) who underwent PVI. All 11 BTS patients became free from both AF and prolonged sinus pauses without pacemaker implantation (23 +/- 14 months of observation). The mean heart rate significantly increased in the control group (P < 0.05), but not in the BTS group after the PVI procedure, although the HRV parameters of root-mean-square successive differences in the adjacent NN intervals, standard deviation of the NN intervals, and high frequency did significantly decrease in both groups (P < 0.05).nnnCONCLUSIONnAlthough the parasympathetic modulation was significantly attenuated after the PVI procedure, the mean heart rate did not increase in the BTS patients, probably due to the pre-existing sinus node dysfunction.

Adenosine testing during cryoballoon ablation and radiofrequency ablation of atrial fibrillation: A propensity score–matched analysis

BACKGROUNDnThe infusion of adenosine triphosphate after radiofrequency (RF) pulmonary vein (PV) isolation (PVI), which may result in acute transient PV-atrium reconnection, can unmask dormant conduction.nnnOBJECTIVEnThe purpose of this study was to compare the incidence and characteristics of dormant conduction after cryoballoon (CB) and RF ablation of atrial fibrillation (AF).nnnMETHODSnOf 414 consecutive patients undergoing initial catheter ablation of paroxysmal AF, 246 (59%) propensity score-matched patients (123 CB-PVI and 123 RF-PVI) were included.nnnRESULTSnDormant conduction was less frequently observed in patients who underwent CB-PVI than in those who underwent RF-PVI (4.5% vs 12.8% of all PVs; P < .0001). The incidence of dormant conduction in each PV was lower in patients who underwent CB-PVI than in those who underwent RF-PVI in the left superior PV (P < .0001) and right superior PV (P = .001). The site of dormant conduction was mainly located around the bottom of both inferior PVs after CB-PVI. Multivariable analysis revealed that a longer time to the elimination of the PV potential (odds ratio 1.018; 95% confidence interval 1.001-1.036; P = .04) and the necessity of touch-up ablation (odds ratio 3.242; 95% confidence interval 2.761-7.111; P < .0001) were independently associated with the presence of dormant conduction after CB-PVI. After the elimination of dormant conduction by additional ablation, the AF-free rate was similar in patients with and without dormant conduction after both CB-PVI and RF-PVI (P = .28 and P = .73, respectively).nnnCONCLUSIONnThe results of the propensity score-matched analysis showed that dormant PV conduction was less frequent after CB ablation than after RF ablation and was not associated with ablation outcomes.

Adenosine-induced atrial tachycardia and multiple foci initiating atrial fibrillation eliminated by catheter ablation using a non-contact mapping system.

A 47-year-old male with both atrial tachycardia and atrial fibrillation underwent catheter ablation. During the procedure, rapid administration of adenosine triphosphate induced atrial tachycardia. A non-contact mapping system revealed a focal atrial tachycardia originating from the lateral right atrium, which was successfully ablated. Following the ablation of tachycardia, atrial fibrillation was induced by the injection of adenosine along with multiple extra pulmonary vein foci, which were eliminated by the application of radiofrequency under the guidance of a non-contact mapping system.