Masaru Arai

Mechanistic Insights Into Durable Pulmonary Vein Isolation Achieved by Second-Generation Cryoballoon Ablation

Background The mechanism explaining the efficacy of cryoballoon ablation (CBA) for atrial fibrillation has not been clarified. Methods and Results We compared lesion characteristics between patients in whom pulmonary vein isolation (PVI) was performed by CBA (n=56) and those by contact force (CF)-based RF ablation (n=56). We evaluated the 3-dimensional PV morphology before and after cryoballoon inflation. After PVI, a 3D left atrial voltage map was created. Pacing (10 mA and 2 ms) was performed within the low voltage area from the ablation line, and electrically unexcitable ablated tissue was identified. ATP-provoked dormant conduction after PVI occurred in 9 of the 224 (4%) PVs in the CBA group and in 13 of the 224 (6%) PVs in the CF group (P=0.3935). The inflated balloon stretched the PV from the original PV ostial surface by 7.1±3.5 mm, but at sites with (vs, sites without) residual PV potential/dormant conduction, the extent of the PV distension was reduced (4.0±4.0 mm vs. 7.2±3.4 mm, P<0.0001). The unexcitable ablated tissue around the PVs was significantly wider in CB patients than in CF patients (16.7±5.1 mm vs. 5.3±2.3 mm, P<0.0001). Conclusions Use of the cryoballoon significantly distends the PV. Without this extensive distention, PVI may not be successful. CBA seems to yield wide unexcitable ablation zones. These factors seem to explain the durability of CBA lesions.

Complete Atrioventricular Block Complicating Mitral Infective Endocarditis Caused by Streptococcus Agalactiae

Patient: Male, 74 Final Diagnosis: Infective endocarditis Symptoms: Apetite loss • fever Medication: — Clinical Procedure: Transesophageal echocardiography Specialty: Cardiology Objective: Rare co-existance of disease or pathology Background: Infective endocarditis (IE) involving the mitral valve can but rarely lead to complete atrioventricular block (CAVB). Case Report: A 74-year-old man with a history of infective endocarditis caused by Streptococcus gordonii (S. gordonii) presented to our emergency room with fever and loss of appetite, which had lasted for 5 days. On admission, results of serologic tests pointed to severe infection. Electrocardiography showed normal sinus rhythm with first-degree atrioventricular block and incomplete right bundle branch block, and transthoracic echocardiography and transesophageal echocardiography revealed severe mitral regurgitation caused by posterior leaflet perforation and 2 vegetations (5 mm and 6 mm) on the tricuspid valve. The patient was initially treated with ceftriaxone and gentamycin because blood and cutaneous ulcer cultures yielded S. agalactiae. On hospital day 2, however, sudden CAVB requiring transvenous pacing occurred, and the patient’s heart failure and infection worsened. Although an emergent surgery is strongly recommended, even in patients with uncontrolled heart failure or infection, surgery was not performed because of the Child-Pugh class B liver cirrhosis. Despite intensive therapy, the patient’s condition further deteriorated, and he died on hospital day 16. On postmortem examination, a 2×1-cm vegetation was seen on the perforated posterior mitral leaflet, and the infection had extended to the interventricular septum. Histologic examination revealed extensive necrosis of the AV node. Conclusions: This rare case of CAVB resulting from S. agalactiae IE points to the fact that in monitoring patients with IE involving the mitral valve, clinicians should be aware of the potential for perivalvular extension of the infection, which can lead to fatal heart block.

Impact of Sinus Node Recovery Time after Long-Standing Atrial Fibrillation Termination on the Long-Term Outcome of Catheter Ablation

Atrial electrical and structural remodeling is related to the perpetuation of atrial fibrillation (AF) subsequent to sinus node dysfunction. We investigated the relationship between AF recurrence after catheter ablation and sinus node dysfunction in long-standing persistent AF patients using the sinus node recovery time (SNRT) after defibrillation.Fifty-one consecutive patients who underwent a first ablation for long-standing persistent AF were enrolled. Intracardiac cardioversion was applied before ablation in the absence of any antiarrhythmic drugs, and the power required to defibrillate, number, and SNRT after defibrillation were measured. All patients underwent the same designed radiofrequency catheter ablation procedure.No patient required permanent pacemaker implantation due to sinus dysfunction after the ablation. During the follow-up period of 28.4 months (3.6-43.7), 35 out of 51 patients (69%) experienced an AF recurrence. The AF recurrence was significantly associated with an older age (60 ± 11 versus 52 ± 12 years in the non-recurrence group, P = 0.0196), longer SNRT after defibrillation (1722 [1410-2656] versus 1295 [676-1651] msec, P = 0.0125), and larger left atrial (LA) volume (59 ± 25 versus 41 ± 15 mL, P = 0.0119). There were no significant differences in the AF duration, AF cycle length, and right and total atrial conduction times between the 2 groups. A longer SNRT after defibrillation (adjusted HR 2.13, 95%CI 1.16-3.71, P = 0.0152) and larger LA volume (adjusted HR 1.03, 95%CI 1.01-1.04, P = 0.0054) were independent predictors of AF recurrence after ablation.Assessment of the SNRT after defibrillation may help to predict a successful ablation in patients with long-standing persistent AF.

Left atrial remodeling: Regional differences between paroxysmal and persistent atrial fibrillation

The mechanisms underlying self‐perpetuation of persistent atrial fibrillation (AF) are not well understood. To gain insight into these mechanisms, we conducted a study comparing left atrial (LA) electroanatomic maps obtained during sinus rhythm between patients with paroxysmal AF (PAF) and patients with persistent AF (PerAF).

Complex fractionated atrial electrograms, high dominant frequency regions, and left atrial voltages during sinus rhythm and atrial fibrillation

Ablation targeting complex fractionated atrial electrograms (CFAEs) or high dominant frequency (DF) sites is generally effective for persistent atrial fibrillation (AF). CFAEs and/or high DF sites may exist in low‐voltage regions, which theoretically represent abnormal substrates. However, whether CFAEs or high DF sites reflect low voltage substrates during sinus rhythm (SR) is unknown.

No association between dormant conduction sites and pulmonary vein reconnection sites in late atrial fibrillation recurrence after catheter ablation

OBJECTIVE Despite use of provocation testing to unmask dormant left atrium (LA)-PV conduction after index pulmonary vein isolation (PVI) for atrial fibrillation (AF), AF recurrence still occurs, with PV reconnection as the main cause. In an effort to answer the question whether freedom from AF recurrence can be achieved by ablation that targets sites of dormant conduction, we compared sites of dormant conduction against sites of PV reconnection identified at the time of repeat ablation for AF recurrence. MATERIALS AND METHODS The study group comprised 46 patients (30 men/16 women, aged 58.7±10.3 years) with AF (paroxysmal: n=37, persistent: n=9) who underwent repeat ablation for AF recurrence 12.3 (7.4-29.7) months after the index ablation procedure. Ipsilateral PVs were divided into 8 segments each (736 total segments), and the relation between dormant conduction sites and PV reconnection sites was determined per segment. RESULTS Dormant LA-PV conduction was unmasked and ablated in 22 (47.8%) of the 46 patients at sites within 43 (5.8%) of the 736 PV segments. Late PV reconnection was found within 122 (17%) of the 736 PV segments at the time of re-ablation for AF recurrence. Only 22 (18%) of these 122 PV segments corresponded to dormant conduction sites identified during the index procedure. CONCLUSION Although additional ablation to eliminate dormant PV conduction unmasked during the index ablation procedure is performed, the majority of PVs that show reconduction at the time of treatment for clinical AF recurrence are PVs that have not shown dormant conduction.

Effect of epicardial fat and metabolic syndrome on reverse atrial remodeling after ablation for atrial fibrillation

Metabolic syndrome/epicardial adipose tissue (EAT) plays an important role in atrial fibrillation (AF). Although reverse atrial remodeling (RAR) often occurs after AF ablation, the effects of EAT on RAR remain unknown.

Influence of balloon temperature and time to pulmonary vein isolation on acute pulmonary vein reconnection and clinical outcomes after cryoballoon ablation of atrial fibrillation

Limited data exist on indicators of durable pulmonary vein isolation (PVI) undergoing cryoballoon ablation (CBA) for atrial fibrillation (AF). We investigated whether balloon temperature and time to PVI can be used to predict early PV reconduction (EPVR), including residual PV conduction and adenosine triphosphate‐induced dormant conduction and the relation between touch‐up ablation of EPVR sites and mid‐term recurrence of AF.

Hot Balloon Versus Cryoballoon Ablation for Atrial Fibrillation: Lesion Characteristics and Middle-Term Outcomes.

Background: Hot balloon ablation (HBA) and cryoballoon ablation (CBA) were developed to simplify ablation for atrial fibrillation. Because the lesion characteristics and efficacy of these balloon modalities have not been clarified, we compared lesion characteristics and outcomes of HBA and CBA. Methods: Of 165 consecutive patients who underwent initial catheter ablation for atrial fibrillation, 74 propensity scorematched (37 HBA and 37 CBA) patients were included in our study. Results: Patients’ clinical characteristics, including age, sex, body mass index, atrial fibrillation subtype, CHA2DS2-VASc score, and left atrial dimension, were similar between the 2 groups. Touch-up radiofrequency ablation was required for residual/dormant pulmonary vein conduction in 52% of the patients with HBA versus 24% of the patients with CBA (P=0.02) and often in the anterior aspect of the left superior pulmonary vein after HBA (41%) versus the inferior aspect of the inferior pulmonary veins after CBA (22%). HBA lesions were smaller than CBA lesions (23.8±7.9 versus 33.5±14.5 cm2; P=0.0007). Similar results were observed when lesions in each pulmonary vein were compared between groups. Twenty-four hours after the procedure, serum levels of the cardiac biomarkers, including troponin-T, creatine kinase, and creatine kinase-MB, were lower in the HBA group than in the CBA group. Atrial fibrillation recurrence did not differ between the groups within 6 (3% versus 11%; P=0.36) or 12 months (16% versus 16%; P=1.00). Conclusions: Although HBA lesions appear to be smaller than CBA lesions, middle-term outcomes are not statistically different between these balloon modalities.

Wavefront direction and cycle length affect left atrial electrogram amplitude

The relationship between atrial electrogram (EGM) characteristics in atrial fibrillation (AF) and those in sinus rhythm (SR) are generally unknown. The activation rate and direction may affect EGM characteristics. We examined characteristics of left atrial (LA) EGMs obtained during pacing from different sites.