Prolonged PR intervals are associated with epicardial adipose tissue and recurrence after catheter ablation in persistent atrial fibrillation.

Epicardial adipose tissue (EAT) has been reported to promote myocardial fibrosis and to affect intracardiac conduction. The PR interval reflects the conduction from the atria to the Purkinje fibers and may be associated with the EAT volume, especially in persistent atrial fibrillation (AF) patients. We aimed to investigate the relationship between the EAT and PR interval in patients with persistent AF. We enrolled 268 persistent AF patients who underwent catheter ablation (CA) and divided the patients into two groups: the normal PR interval group (PR interval less than 200 ms: Group N) and long PR interval group (PR interval 200 ms or more: Group L). We then analyzed the association between the total EAT volume around the heart and PR interval and calculated the ratio of the duration of the P wave (PWD) to the PR interval (PWD/PR interval). Moreover, we investigated whether a long PR interval was associated with the outcomes after ablation. The total EAT volume was significantly larger in Group L than Group N (Group N: 131.4 ± 51.8 ml vs. Group L: 151.3 ± 63.3 ml, p = 0.039). A positive correlation was also observed between the PWD/PR interval and EAT volume in Group L (r = 0.345, p = 0.039). A multivariate analysis also revealed that a long PR interval was independently associated with AF recurrence after CA (hazard ratio [HR] 2.071, p = 0.032). The total EAT volume was associated with a long PR interval, and a long PR interval was a significant risk factor for recurrence after ablation in persistent AF patients.

Impact of Lipoprotein (a) on Long-Term Outcomes in Patients With Acute Myocardial Infarction.

BACKGROUND: Lipoprotein (a) (Lp(a)) is a complex circulating lipoprotein, and there is increasing evidence it is a risk factor for atherosclerotic cardiovascular disease (ASCVD). This study aimed to investigate the influence of Lp(a) serum levels on long-term outcomes after acute myocardial infarction (AMI).Methods and Results: Between January 2015 and January 2018, we enrolled 262 patients with AMI who underwent coronary angiography within 24 h of the onset of chest pain and had available Lp(a) data enabling subdivision into 2 groups: high Lp(a) (≥32 mg/dL: n=76) and low Lp(a) (<32 mg/dL: n=186). The primary endpoint was major adverse cardiac events (MACE), which was defined as a composite of cardiac death, nonfatal MI, and readmission for heart failure. Multivariate Cox regression analysis was performed to identify the predictors of MACE. The incidence of MACE was significantly higher in the high Lp(a) group than in the low Lp(a) group (32.8% vs. 19.6%, P=0.004). Multivariate analysis showed that Lp(a) ≥32 mg/dL was an independent predictor of MACE (hazard ratio 2.84, 95% confidence interval 1.25-6.60, P=0.013). CONCLUSIONS: High Lp(a) levels were associated with worse long-term outcomes after AMI, so Lp(a) may be useful for risk assessment.

New Minimally Invasive and Tailor-Made Strategy for Cryoballoon Ablation in Patients With Paroxysmal Atrial Fibrillation.

BACKGROUND: The optimal dosage for cryoballoon ablation (CBA) of atrial fibrillation (AF) is still unknown. OBJECTIVE: This study aimed to evaluate the clinical implications of a reduction in the freezing duration to <180 seconds during CBA guided by the time to the target temperature. METHODS: This study enrolled 325 consecutive paroxysmal AF patients who underwent CBA. It was a retrospective observational study in a single centre. It compared 164 patients who underwent a tailor-made CBA procedure (group T) with 161 who had a standard CBA procedure (group S). In group T, the freezing duration was reduced to 150 seconds when the temperature reached ≤ -40 °C within 40 seconds. Furthermore, it was reduced to 120 seconds when it reached ≤ -50 °C within 60 seconds. In the other patients, the freezing duration was 180 seconds, except for excessive freezing of ≤ -60 °C and/or emergent situations while monitoring the oesophageal temperature, and for phrenic nerve injury, as in group S. RESULTS: In group T, 89 patients (83%) underwent CBA with a reduction in the freezing duration. The total freezing time for each pulmonary vein was significantly shorter in group T than group S, and the total procedure time in group T decreased by an average of 4 minutes compared with group S. The rate of requiring additional radio frequency ablation following the CBA was significantly lower in group T than group S. The AF-free survival rate during the follow-up period (median, 366 days) was similar between the two groups. CONCLUSION: The safety and efficacy of the new CBA strategy were non-inferior to the standard procedure.

Refractoriness to subcutaneous implantable cardioverter defibrillator after frequent therapies for ventricular fibrillation storms in a Brugada syndrome case.

BACKGROUND: The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to the transvenous implantable cardioverter defibrillator for the prevention of sudden cardiac death. Here, we report a rare case of refractoriness to an S-ICD after frequent therapies for ventricular fibrillation (VF) storms. CASE PRESENTATION: A 24-year-old man underwent a bout of syncope with vomiting and incontinence at home. He was brought to the emergency room and was witnessed to spontaneously go into VF successfully converted by external defibrillation. Previously, he was diagnosed with a type I Brugada electrocardiogram pattern by a pilsicainide administration test in another hospital. Although he had a family history of sudden cardiac death in 3 relatives, including his brother, he was followed closely without any therapies because he had never had an episode of syncope. He was implanted with an S-ICD without any trouble. Seven months later, frequent S-ICD shocks for VF storms occurred. His VF was controlled by using intravenous amiodarone, which was converted to an oral preparation. However, his VF recurred after another 2 months. The analysis of his S-ICD data revealed that 4 consecutive shock deliveries could not terminate his VF and the final shock delivered could fortunately terminate it because of a high defibrillation threshold test (DFT) due to an increasing shock impedance (64 to 90 Ω). First, we performed an epicardial Brugada syndrome ablation and subsequently replaced and repositioned the S-ICD lead from a left to a right parasternal site. After the re-implantation of the S-ICD, the DFT test improved to within normal range. According to the pathological analysis, infiltration of inflammatory cells and extensive fibrosis were confirmed in the subcutaneous tissue around the shock lead and S-ICD body. CONCLUSION: Frequent S-ICD shocks for VF storms might cause various pathological changes around the device and lead to a high DFT.

Electrical Remodeling of the Atrioventricular Node Caused by Persistent Atrial Fibrillation in Humans.

BACKGROUND: An animal experiment showed that long-term atrial pacing or persistent atrial fibrillation (AF) caused electrical remodeling of the atrioventricular (AV) node. We aimed to test the hypothesis that persistent AF decreases the AV conductivity in human hearts. METHODS AND RESULTS: We retrospectively compared the cardiac electrophysiological properties between patients with paroxysmal AF who underwent catheter ablation (PXAF, N = 254) and those with persistent or longstanding persistent AF (PSAF, N = 213). The PSAF patients were more likely than PXAF patients to have longer atrial-His (AH) (96.3 ± 25.7 vs. 91.3 ± 20.4 milliseconds; P = 0.02) and His-ventricle (HV) (43.1 ± 9.4 vs. 41.2 ± 8.6 milliseconds; P = 0.02) intervals. The AV nodal effective refractory period (ERP) (299.1 ± 74.6 vs. 276.2 ± 58.9 milliseconds; P < 0.001) and Wenckebach cycle length (420.9 ± 80.3 vs. 386 ± 58.6 milliseconds; P < 0.001) were also more prolonged in the PSAF patients. We found a dual AV nodal physiology with a similar frequency in both groups. The AH interval, fast pathway ERP, and Wenckebach cycle length in the PSAF patients were more likely than in the PXAF patients to be prolonged among the patients without dual pathways, while those intergroup differences were never seen among the patients with dual pathways. In subgroup analyses including only PSAF patients, there was no difference in the AV conductivity between the patients with persistent AF and those with longstanding persistent AF. CONCLUSIONS: Persistent AF may cause a mild decrease in the AV nodal function in human hearts. Electrical remodeling may be uncommon if dual AV nodal pathways are present, and its extent may not depend on the duration of persistent AF.

Dexmedetomidine Depresses Sinoatrial and Atrioventricular Nodal Function Without Any Change in Atrial Fibrillation Inducibility.

It has been reported that dexmedetomidine (dex) has an impact on the cardiac conduction system and even has potential antiarrhythmic actions. We examined the influence of dex on the cardiac electrophysiological properties and atrial fibrillation (AF) inducibility. Adult paroxysmal AF patients were randomly assigned to receive (N = 107) or not receive (N = 108) dex during cardiac electrophysiological studies. The corrected sinus node recovery time (558 ± 331 vs. 459 ± 260 milliseconds; P = 0.02), Wenckebach cycle length (P < 0.001), atrioventricular nodal effective refractory period (317 ± 76 vs. 252 ± 54 milliseconds; P < 0.001), and atrio-His interval (P < 0.001) were longer in patients with dex than in those without. We tested the induction of repetitive atrial firing (RFA) defined as the occurrence of ≥2 successive atrial activities induced by single premature atrial stimuli to determine the AF inducibility. RFA was seen with a similar proportion (41.1% vs. 44.4%), yet it was evoked at a longer stimulus coupling interval in the dex patients, which was potentially attributed to the longer atrial effective refractory period (237 ± 36 vs. 213 ± 27 milliseconds; P < 0.001) and more prolonged atrial conduction delay seen in the dex group. In conclusion, dex may depress the sinus and atrioventricular nodal function, however, it may not reduce the AF inducibility.

A nonsynonymous polymorphism in semaphorin 3A as a risk factor for human unexplained cardiac arrest with documented ventricular fibrillation.

Unexplained cardiac arrest (UCA) with documented ventricular fibrillation (VF) is a major cause of sudden cardiac death. Abnormal sympathetic innervations have been shown to be a trigger of ventricular fibrillation. Further, adequate expression of SEMA3A was reported to be critical for normal patterning of cardiac sympathetic innervation. We investigated the relevance of the semaphorin 3A (SEMA3A) gene located at chromosome 5 in the etiology of UCA. Eighty-three Japanese patients diagnosed with UCA and 2,958 healthy controls from two different geographic regions in Japan were enrolled. A nonsynonymous polymorphism (I334V, rs138694505A>G) in exon 10 of the SEMA3A gene identified through resequencing was significantly associated with UCA (combined P = 0.0004, OR 3.08, 95%CI 1.67-5.7). Overall, 15.7% of UCA patients carried the risk genotype G, whereas only 5.6% did in controls. In patients with SEMA3A(I334V), VF predominantly occurred at rest during the night. They showed sinus bradycardia, and their RR intervals on the 12-lead electrocardiography tended to be longer than those in patients without SEMA3A(I334V) (1031±111 ms versus 932±182 ms, P = 0.039). Immunofluorescence staining of cardiac biopsy specimens revealed that sympathetic nerves, which are absent in the subendocardial layer in normal hearts, extended to the subendocardial layer only in patients with SEMA3A(I334V). Functional analyses revealed that the axon-repelling and axon-collapsing activities of mutant SEMA3A(I334V) genes were significantly weaker than those of wild-type SEMA3A genes. A high incidence of SEMA3A(I334V) in UCA patients and inappropriate innervation patterning in their hearts implicate involvement of the SEMA3A gene in the pathogenesis of UCA.

High plasma human atrial natriuretic peptide and reduced transthoracic left atrial appendage wall-motion velocity are noninvasive surrogate markers for assessing thrombogenesis in patients with paroxysmal atrial fibrillation.

BACKGROUND: The clinical relevance of examining human atrial natriuretic peptide (HANP) or left atrial appendage (LAA) wall-motion velocity during sinus rhythm in paroxysmal atrial fibrillation (AF) patients has not been clearly elucidated. METHODS: The subjects were 38 patients with paroxysmal AF who underwent transesophageal and transthoracic echocardiography during sinus rhythm. The presence of spontaneous echocontrast (SEC) was examined with transesophageal echocardiography and LAA wall-motion velocity (LAAWV) was measured with transthoracic tissue Doppler echocardiography. Plasma HANP was measured within 3 hours after echocardiography. RESULTS: Human atrial natriuretic peptide ranged from 12 to 106 pg/mL with an average of 43 ± 24 pg/mL and had a significant correlation with LAAWV (r = -0.57) or LAA flow velocity (r = -0.41). HANP was significantly higher in patients with SEC than in patients without SEC (64 ± 29 vs. 34 ± 15 pg/mL, P = 0.008) and LAAWV was significantly lower in patients with SEC than in patients without SEC (13 ± 5 vs. 20 ± 5 cm/sec, P = 0.002). HANP >44 pg/mL had a sensitivity of 73% and specificity of 89% for diagnosing SEC. SEC was more frequently observed (73%) in patients with HANP >44 pg/mL and/or LAAWV <10 cm/sec as compared with patients (11%) with normal HANP and LAA wall-motion velocity (P < 0.0001). CONCLUSION: Higher plasma HANP and lower LAA wall-motion velocity may be noninvasive surrogate markers for assessing left atrial thrombogenesis during sinus rhythm in paroxysmal AF patients.

Variable procedural strategies adapted to anatomical characteristics in catheter ablation of the cavotricuspid isthmus using a preoperative multidetector computed tomography analysis.

OBJECTIVES: This study aimed to investigate the anatomical characteristics complicating cavotricuspid isthmus (CTI) ablation and the effectiveness of various procedural strategies. METHODS AND RESULTS: This study included 446 consecutive patients (362 males; mean age 60.5 ± 10.4 years) in whom CTI ablation was performed. A total of 80 consecutive patients were evaluated in a preliminary study. The anatomy of the CTI was evaluated by multidetector row-computed tomography (MDCT) prior to the procedure. A multivariate logistic regression analysis revealed that the angle and mean wall thickness of the CTI, a concave CTI morphology, and a prominent Eustachian ridge, were associated with a difficult CTI ablation (P < 0.01). In the main study, 366 consecutive patients were divided into 2 groups: a modulation group (catheter inversion technique for a concave aspect, prominent Eustachian ridge, and steep angle of the CTI or increased output for a thicker CTI) and nonmodulation group (conventional strategy). The duration and total amount of radiofrequency energy delivered were significantly shorter and smaller in the modulation group than those in the nonmodulation group (162.2 ± 153.5 vs 222.7 ± 191.9 seconds, P < 0.01, and 16,962.4 ± 11,545.6 vs 24,908.5 ± 22,804.2 J, P < 0.01, respectively). The recurrence rate of type 1 atrial flutter after the CTI ablation in the nonmodulation group was significantly higher than that in the modulation group (6.3 vs 1.7%, P = 0.02). CONCLUSION: Changing the procedural strategies by adaptating them to the anatomical characteristics improved the outcomes of the CTI ablation.

Pulmonary artery mapping for differential diagnosis of left-sided atrial tachycardia.

BACKGROUND: Distinguishing left-and right-sided atrial tachycardia (AT) is often challenging. The coronary sinus (CS) provides information only concerning the anterior left atrium (LA). Potentials recorded in the pulmonary artery (PA) have been substituted for those of the upper posterior LA because of their anatomical relationship. METHODS AND RESULTS: Three patterns were designed, using potentials in the PA, right atrium (RA) and CS, to predict the side of AT. Two patterns were for left-sided AT and 1 pattern was for right-sided AT. Ten left-sided and 11 right-sided ATs were investigated regardless of mechanism. Electrode catheters were inserted in the RA, His bundle region, and CS, and an ablation catheter was inserted into the left and/or right PA. The sequences from these catheters were analyzed before detailed electroanatomical mapping. Patterns were obtained for 20 of 21 ATs. The mechanism was focal in 16 ATs and macroreentry in 5. The method predicted left-sided AT with a sensitivity of 78%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 84%, and an accuracy of 90%. CONCLUSIONS: The use of potentials in PA combined with conventional RA and CS electrograms is useful for distinguishing left-sided AT from right-sided AT, regardless of mechanism.

Left atrial thickness under the catheter ablation lines in patients with paroxysmal atrial fibrillation: insights from 64-slice multidetector computed tomography.

A detailed understanding of the left atrial (LA) anatomy in patients with atrial fibrillation (AF) would improve the safety and efficacy of the radiofrequency catheter ablation. The objective of this study was to examine the myocardial thickness under the lines of the circumferential pulmonary vein isolation (CPVI) using 64-slice multidetector computed tomography (MDCT). Fifty-four consecutive symptomatic drug-refractory paroxysmal AF patients (45 men, age 61 ± 12 years) who underwent a primary CPVI guided by a three-dimensional electroanatomic mapping system (Carto XP; Biosense-Webster, Diamond Bar, CA, USA) with CT integration (Cartomerge; Biosense-Webster) were enrolled. Using MDCT, we examined the myocardial thickness of the LA and pulmonary vein (PV) regions in all patients. An analysis of the measurements by the MDCT revealed that the LA wall was thickest in the left lateral ridge (LLR; 4.42 ± 1.28 mm) and thinnest in the left inferior pulmonary vein wall (1.68 ± 0.27 mm). On the other hand, the thickness of the posterior wall in the cases with contact between the esophagus and left PV antrum was 1.79 ± 0.22 mm (n = 30). After the primary CPVI, the freedom from AF without any drugs during a 1-year follow-up period was 78 % (n = 42). According to the multivariate analysis, the thickness of the LLR was an independent positive predictor of an AF recurrence (P = 0.041). The structure of the left atrium and PVs exhibited a variety of myocardial thicknesses in the different regions. Of those, only the measurement of the LLR thickness was associated with an AF recurrence.

Efficacy of pulmonary vein isolation on left atrial function in paroxysmal and persistent atrial fibrillation and the dependency on its baseline function.

BACKGROUND: The effects of pulmonary vein (PV) isolation in atrial fibrillation (AF) on left atrial (LA) function or PV flow have not been well documented. METHODS: We examined the LA function and PV flow before and 3-6 months after PV isolation in 67 AF patients (34 paroxysmal [PAF] and 33 persistent [CAF]) using transesophageal echocardiography. RESULTS: AF recurred in 6/34 patients with PAF and in 6/33 patients with CAF 6 months after PV isolation. A larger LA dimension, a lower systolic PV flow velocity, and a lower ratio of systolic to diastolic PV flow velocity were related to a higher incidence of AF recurrence. The increment of left atrial appendage (LAA) flow velocity (55% vs. 22%) and systolic PV flow velocity (57% vs. 20%) after PV isolation tended to be greater in CAF than in PAF. The changes in LAA flow velocity had reverse correlations with the baseline values before PV isolation (PAF: r = -0.73, CAF: r = -0.58). The changes in mitral flow velocity during atrial contraction in PAF had reverse correlations with the baseline values before PV isolation (r = -0.84). The changes in systolic and diastolic PV flow velocity of PAF had reverse correlations with the baseline values before PV isolation (r = -0.56, r = -0.66). CONCLUSION: The baseline LA function may affect AF recurrence as well as the improvement of LA function, and the benefit of successful PV isolation might be greater in CAF than in PAF.

Effects of ivabradine on the pulmonary vein electrical activity and modulation of pacemaker currents and calcium homeostasis.

INTRODUCTION: Ivabradine is a novel heart rate decreasing agent with selective and specific antagonist effects on the pacemaker current (I(f)). The aim of this study was to investigate the pharmacological effects of ivabradine on the pulmonary vein (PV) cardiomyocytes. METHODS AND RESULTS: Whole-cell patch-clamp techniques and the indo-1 fluorimetric ratio technique were used to investigate the characteristics of the I(f) and intracellular calcium (Ca(2+)(i)) in single isolated rabbit PV cardiomyocytes with pacemaker activity before and after an ivabradine administration (0.3, 3, 10, and 30 µM). Ivabradine (0.3, 3, 10, and 30 µM) concentration dependently decreased the spontaneous activity by 6 ± 3%, 32 ± 6%, 49 ± 5%, and 85 ± 4%, and decreased the I(f) by 35 ± 8%, 47 ± 9%, 62 ± 5%, and 65 ± 7%, respectively, in PV cardiomyocytes. The decreased extent of the PV beating rate or I(f) by the different concentrations of ivabradine correlated well with the baseline PV beating rates. The IC(50) of the spontaneous activity and I(f) induced by ivabradine were 9.5 and 3.5 µM, respectively. Moreover, ivabradine (30 µM, but not 3 µM) decreased the Ca(2+)(i) transient in the PV cardiomyocytes and ivabradine (30 µM) decreased the L-type calcium current in the PV cardiomyocytes. CONCLUSION: Ivabradine decreased the I(f)s and Ca(2+)(i) transient in the PV cardiomyocytes, which may contribute to its inhibitory effects on the PV spontaneous activity.

A novel finding of the atrial substrate properties and long-term results of catheter ablation in chronic atrial fibrillation patients with left atrial spontaneous echo contrast.

BACKGROUND: The atrial substrate in chronic atrial fibrillation (AF) patients with a left atrial spontaneous echo contrast (LASEC) has not been previously reported. The aim of this study was to investigate the atrial substrate properties and long-term follow-up results in the patients who received catheter ablation of chronic AF. METHODS: Of 36 consecutive patients with chronic AF who received a stepwise ablation approach, 18 patients with an LASEC (group I) were compared with 18 age-gender-left atrial volume matched patients without an LASEC (group II). The atrial substrate properties including the weighted peak-to-peak voltage, total activation time during sinus rhythm (SR), dominant frequency (DF), and complex fractionated electrograms (CFEs) during AF in the bi-atria were evaluated. RESULT: The left atrial weighted bipolar peak-to-peak voltage (1.0 ± 0.6 vs 1.6 ± 0.7 mV, P = 0.04), total activation time (119 ± 20 vs 103 ± 13 ms, P < 0.001) and DF (7.3 ± 1.3 vs 6.6 ± 0.7 Hz, P < 0.001) differed between group I and group II, respectively. Those parameters did not differ in the right atrium. The bi-atrial CFEs (left atrium: 89 ± 24 vs 92 ± 25, P = 0.8; right atrium: 92 ± 25 vs 102 ± 3, P = 0.9) did not differ between group I and group II, respectively. After a mean follow-up of 30 ± 13 month, there were significant differences in the antiarrhythmic drugs (1.1 ± 0.3 vs 0.7 ± 0.5, P = 0.02) needed after ablation, and recurrence as persistent AF (92% vs 50%, P = 0.03) between group I and group II, respectively. After multiple procedures, there were more group II patients that remained in SR, when compared with group I (78% vs 44%, P = 0.04). CONCLUSION: There was a poorer atrial substrate, lesser SR maintenance after catheter ablation and need for more antiarrhythmic drugs in the chronic AF patients with an LASEC when compared with those without an LASEC.

A prospective, randomized comparison of modified pulmonary vein isolation versus conventional pulmonary vein isolation in patients with paroxysmal atrial fibrillation.

INTRODUCTION: Pulmonary vein isolation (PVI) is the primary ablation therapy in patients with atrial fibrillation (AF). We hypothesized that high dominant frequency (DF) sites (AF nests during sinus rhythm [SR]) adjacent to the PV ostia are associated with the atrial substrate that maintains AF, and PVI incorporating the high-frequency AF nests may have a higher efficacy. METHODS AND RESULTS: In a prospective and randomized comparison, 126 symptomatic paroxysmal AF patients that underwent PVI were enrolled. We compared the efficacy of a modified PVI (ablation line: 1.0-1.5 cm from the PV ostium with encircling the AF nests [spectral analysis with DF >70 Hz during SR, Group II]) versus the anatomy-guided conventional PVI (Group I). In Group II, the DF value along the PV ostium was lower than 70 Hz after the PVI. The primary endpoint was the freedom from symptomatic atrial arrhythmias after a single procedure. We also followed the autonomic function by a time-domain analysis of the heart rate variability. In both groups, AF nests were observed and electric isolation was successfully obtained in all patients. With a mean duration of 16 ± 6.1 months of follow-up, Group II had a higher single procedure efficacy without drugs (78.7% vs 66.1%, log-rank test: P = 0.02), and fewer repeat procedures (6.6% vs 23%; P = 0.04), as compared to Group I. CONCLUSION: PVI incorporating the high frequency AF nests adjacent to the PV ostia had a better single procedure efficacy.

Consistency of the automatic algorithm in detecting complex fractionated electrograms using an electroanatomical navigation system.

BACKGROUND: The different settings of the automatic algorithm in the Carto system (Carto XP, Biosense Webster, Diamond Bar, CA, USA) used for detecting complex fractionated electrograms (CFEs) during atrial fibrillation (AF) may influence the identification of the fragmented electrograms. OBJECTIVES: We aimed to evaluate the impact of the different parameters on the detection of CFEs and the efficacy of the substrate modification after pulmonary vein isolation (PVI). METHODS: A total of 1,159 electrograms were analyzed from 11 consecutive patients (age = 56 ± 12 years). The effect of the different algorithm factors, such as the high-voltage thresholds (0.12, 0.25, 0.5, 20 mV), detection algorithms (average complex interval [ACI] vs interval confidence level), and recording duration (2.5 seconds vs 5 seconds), on the disparities of the CFEs was investigated. RESULTS: The proportion of the different grades of CFEs depended on the detection algorithm and recording duration. The high-voltage threshold would not affect the consistency of the CFEs irrespective of the different settings of the detection algorithm or recording duration. High-grade CFEs were most consistent with an ACI algorithm and recording duration of 5 seconds (Cronbach's alpha = 0.952). Ablation consisting of a PVI and high-grade CFE sites converted AF directly to sinus rhythm in eight of 11 patients or into atrial tachycardia in one of 11. CONCLUSIONS: The distribution and consistency of the CFE detection depended on the detection algorithm and recording duration, but not on the high-voltage threshold. Under the ACI algorithm and a recording duration of 5 seconds, high-grade CFE sites remained highest consistency.

Comparison between cryoballoon and hot balloon ablation in patients with paroxysmal atrial fibrillation.

PURPOSE: Pulmonary vein (PV) isolation using balloon ablation was developed as a technique for patients with paroxysmal atrial fibrillation (PAF). While most studies examined cryoballoon ablation (CBA), there have also been many reports on hot balloon ablation (HBA). We aimed to evaluate the clinical characteristics and outcomes between HBA and CBA. METHODS: In a total of 103 consecutive patients with PAF who underwent catheter ablation, 60 propensity score-matched (30 CBA and 30 HBA) patients were enrolled. The procedural differences and clinical outcomes between the two groups were analyzed. RESULTS: The requirement for additional touch-up ablation was more frequent in the left superior pulmonary vein (LSP) in the HBA group than in the CBA group. Pre-procedural computed tomography (CT) images showed that a thicker left pulmonary vein ridge and larger cross-sectional area of the LSPV were significantly associated with residual PV potentials after HBA. However, post-procedural CT images showed that PV stenosis (> 25%) was higher in the HBA group (33%) than in the CBA group (0%). PV stenosis after HBA was observed most frequently in the right superior PV (50%). The atrial fibrillation/atrial tachycardia-free survival rate during follow-up (365 ± 102 days) was similar between the two groups (CBA vs. HBA, 83% vs. 90%). CONCLUSIONS: Although both balloon modalities can relieve atrial arrhythmia after the procedure, careful attention is required during HBA procedures, especially for the right superior PV, to avoid PV stenosis.

Low-molecular-weight dextran-induced anaphylactic shock immediately after intracoronary imaging.

Dextran has been frequently used during intracoronary imaging, such as in optical coherence tomography, optical frequent domain imaging, and coronary angioscopy. We report a case of dextran-induced anaphylaxis in a 70-year-old male with chronic coronary disease. Upon admission, we performed coronary angiography and coronary angioscopy on the patient. After the intracoronary imaging, the patient's blood pressure suddenly fell to 50 mmHg and a rash appeared on his chest. The patient was diagnosed as having dextran-induced anaphylactic shock. Epinephrine was administered repeatedly, and his blood pressure gradually recovered after administering a total of 6 mg epinephrine. There was no recurrence of the anaphylactic shock, and the patient was discharged 12 days later. The incidence of dextran-induced anaphylactic reactions is extremely low; however, they can be fatal. The possibility of anaphylactic shock induced by dextran should be kept in mind by all cardiovascular interventionalists performing intracoronary imaging. Learning objective: Dextran has been frequently used during intracoronary imaging. We report on a case of dextran-induced anaphylaxis in a 70-year-old male with chronic coronary disease. While the incidence of dextran-induced anaphylactic reactions is extremely low, it can lead to fatal events. The possibility of anaphylactic shock induced by dextran should be kept in mind by all cardiovascular interventionalists while performing intracoronary imaging.

Discrepant electrophysiological characteristics and calcium homeostasis of left atrial anterior and posterior myocytes.

The left atrial (LA) posterior wall has been demonstrated to have regional electrophysiological differences with a higher arrhythmogenic potential leading to atrial fibrillation (AF). However, the ionic characteristics and calcium regulation in the LA anterior and posterior myocytes have not been fully elucidated. The purpose of this study was to investigate the electrical characteristics of the LA anterior and posterior myocytes. Whole-cell patch-clamp techniques and the indo-1 fluorimetric ratio technique were used to investigate the characteristics of the ionic currents, action potentials, and intracellular calcium in single isolated rabbit myocytes in the LA anterior and posterior walls. The expression of the Na(+)-Ca(2+) exchanger (NCX) and ryanodine receptor (RyR) were evaluated by a Western blot. The LA posterior myocytes (n = 15) had a higher incidence (53 vs. 19%, P < 0.05) of delayed afterdepolarizations than the LA anterior myocytes (n = 16). The LA posterior myocytes had larger sodium currents and late sodium currents, but smaller inward rectifier potassium currents than the LA anterior myocytes. The LA posterior myocytes had larger intracellular Ca(2+) transient and sarcoplasmic reticulum Ca(2+) contents as compared with the LA anterior myocytes. However, the NCX currents in the LA posterior myocytes were smaller than those in the LA anterior myocytes. The LA posterior myocytes had a smaller protein expression of NCX, but a larger protein expression of RyR than the LA anterior myocytes. In conclusion, LA posterior myocytes contain a high arrhythmogenic potential and distinctive electrophysiological characteristics, which may contribute to the pathophysiology of AF.

Relationship between arrhythmogenic pulmonary veins and the surrounding atrial substrate in patients with paroxysmal atrial fibrillation.

INTRODUCTION: The relationship between pulmonary veins (PVs) with atrial fibrillation (AF) initiating triggers and their surrounding atrial substrate has not been elucidated. We aimed to clarify the atrial substrate properties around the PVs. METHODS AND RESULTS: Twenty-three paroxysmal AF patients were studied with the identification of PV initiating triggers. High-density mapping of the dominant frequency (DF, 1200 Hz) and the mean degree of the complex fractionated electrograms (CFE mean interval over 6 seconds) was evaluated in 2 zones (zone 1: < 5 mm, zone 2: 5-15 mm from the PVs) and the left atrial (LA) using a NavX system prior to the PV isolation. High-DFs (>8 Hz) and continuous CFEs (<50 ms) were identified in 1.5 ± 0.9 and 2.3 ± 1.1 regions per patient, respectively. Most of the high-DF regions (86%) and continuous CFE regions (77%) were located within 15 mm of the PV ostia. Of those, 75% of the high-DF regions and 54% of the continuous CFE regions were related to arrhythmogenic PVs. There was a significant DF gradient from arrhythmogenic PV zone 1 to zone 2, while the mean CFE exhibited a significant gradient between arrhythmogenic PV zone 2 and the rest of the LA. Additionally, 69% of the procedural AF termination sites were at arrhythmogenic PV zone 2. CONCLUSION: Evaluation of the atrial substrate properties may be useful for locating arrhythmogenic PVs during AF and defining the extent of the circumferential PV isolation.