Pulmonary vein re-mapping after cryoballoon ablation for atrial fibrillation.

Aims: Establishment of pulmonary vein isolation (PVI) during cryoballoon (CB) ablation is generally confirmed by use of an octapolar inner-lumen mapping catheter (Achieve®). The aim of this study is to evaluate the residual PV potential (PVP) using the conventional circular catheter after CB-PVI. Methods and results: A total of 105 consecutive patients (418 PVs) with paroxysmal AF who underwent the initial CB-PVI were prospectively included in this study. Of those, 305 (73%) PVs with real-time recordings of PVP elimination by Achieve® catheter during successful PVI were included. After isolation of all 4 PVs, PV antral remapping by conventional circular mapping catheter was performed. After CB-PVI, residual PVP was detected in 4.3% (13/305) of PVs (1.2% of left-superior PV, 2.5% of left-inferior PV, none of right-superior PV, and 20% of right-inferior PV). Almost 60% of residual PV potential was located around the bottom portion of the right-inferior PV. In PVs with residual potential, PV trunk was shorter (12.7 ± 5.7 mm vs. 18.7 ± 7.9, P = 0.001), minimal balloon temperature was higher (-46.6 ± 5.9 °C vs. -50.9 ± 8.2, P = 0.02), and balloon warming time was shorter (35.6 ± 17.8 s vs. 50.0 ± 22.8, P = 0.006) than those without. All residual potentials were eliminated by additional touch up ablation. After the initial ablation procedure, 1-year AF-free rate was 79.5%. Conclusion: PV remapping after CB-PVI revealed residual antral PVP in 4.3% of PVs and in 20% of RIPVs in particular. The Achieve® catheter sometimes fails to detect complete PV antral isolation.

Atrial fibrillation diagnosed by a medical checkup is associated with a poor outcome of catheter ablation.

Atrial fibrillation (AF), especially asymptomatic cases, is often detected by medical checkups. We investigated the outcome of AF ablation in cases detected by medical checkups. We reviewed the data of 735 patients with AF (56 ± 10 years, paroxysmal: 441 patients) who underwent initial catheter ablation. All patients were divided into two groups based on their AF being diagnosed either by a medical checkup (group M) or not (group NM). AF was diagnosed by medical checkups in 263 (36%) patients. In Group M, the age was younger, time from the diagnosis to ablation shorter, left atrium dimension larger, and left ventricular ejection fraction lower than in Group NM. Male gender, persistent AF, and asymptomatic AF were more frequently seen in Group M than in Group NM. A mean of 13 ± 11 months after the initial ablation procedure, AF recurrence was more frequently observed in group M compared to group NM (P = 0.018). While the AF recurrence rate was similar in both groups in persistent AF patients (P = 0.87), it was more frequently observed in Group M than in Group NM in paroxysmal AF patients (P = 0.005). AF diagnosed by medical checkups was often associated with a worse outcome of catheter ablation, especially in paroxysmal AF patients.

Radiofrequency needle for transseptal puncture is associated with lower incidence of thromboembolism during catheter ablation of atrial fibrillation: propensity score-matched analysis.

Atrial fibrillation (AF) ablation requires transseptal puncture to access the left atrium. Recently, a radiofrequency (RF) needle was developed. The purpose of this study was to compare the incidence of MRI-confirmed acute cerebral embolism (ACE) during AF ablation procedures performed with RF needle versus mechanical needle transseptal puncture. This study consisted of 383 consecutive patients who underwent catheter ablation for AF that required transseptal puncture with mechanical or radiofrequency transseptal needles. Of those, 232 propensity score-matched patients (116 with each needle type) were included in the analysis. All patients had cerebral MRI performed 1 or 2 days after the procedure. Baseline characteristics were similar between the two groups. Total procedure time was significantly shorter in Group RF than Group non-RF (167 ± 50 vs. 181 ± 52 min, P = 0.01). ACE was detected by MRI in 59 (25%) patients. All patients with ACE were asymptomatic. Incidence of ACE was lower in Group RF than Group non-RF (19 vs. 32%, P = 0.02). B-type natriuretic peptide level was higher in the patients with ACE as compared to those without ACE (65.2 ± 68.7 vs. 44.7 ± 55.1 pg/ml, P = 0.02). In multivariable analysis, the use of RF needle and BNP level was related to the incidence of ACE (OR = 0.499, 95% CI 0.270-0.922, P = 0.03 and OR = 1.005, 95% CI 1.000-1.010, P = 0.03). Use of RF needle for transseptal puncture was associated with lower total procedure time and risk of ACE during catheter ablation of AF.

Total absence of pulmonary vein potentials in a patient with paroxysmal atrial fibrillation: was it really isolated?

We herein present a case (72 years, male) with total absence of pulmonary veins (PVs) potentials at the beginning of the first procedure for paroxysmal atrial fibrillation (AF), demonstrating dormant conduction between the left atrium and all PVs revealed by adenosine triphosphate provocation with relation to the incidence of AF. He was free from atrial arrhythmias during 1 year follow-up after complete PV isolation with the elimination of multiple transient dormant conductions by circular mapping catheter guide ablation.

Characteristics of Clinical and Induced Ventricular Tachycardia Throughout Multiple Ablation Procedures.

BACKGROUND: Optimal procedure endpoints of catheter ablation for ventricular tachycardia (VT) are not defined and multiple repeat procedures are sometimes required. However, there are few studies to compare the details of repeat procedures to the initial procedure. The aim of this study is to compare the characteristics of clinical and induced VT throughout multiple procedures and clarify their relations. METHODS AND RESULTS: Of 425 consecutive patients with structural heart disease who underwent catheter VT ablation, second, third and fourth procedures were performed in 101, 23, and 5 patients, respectively. Of 227 VTs that were induced during the second procedure, 68 (30%) VTs had previously been induced at the first procedure. In multivariable analysis, identification of an exit/isthmus site (HR = 0.29, P = 0.047), early termination of VT during radiofrequency application (HR 0.11, P = 0.037) and elimination of target VT at the end of first procedure (HR = 0.43, P = 0.036) were independently associated with noninducibility of the same VT at the second procedure. Over the course of multiple procedures the mean VT cycle length gradually lengthened (381 ± 107, 413 ± 111, 460 ± 124, 507 ± 99 milliseconds in first, second, third, and fourth procedure, respectively, P < 0.001) and more induced VTs became mappable (32%, 40%, 62%, and 70% in first, second, third, and fourth procedure, respectively, P < 0.001). CONCLUSIONS: Identification and ablation of VT exit/isthmus, early termination of VT during radiofrequency application and elimination of targeted VT are associated with absence of that VT during a repeat procedure, and recurrences are then mostly due to new VTs or other VTs that were not induced at the first procedure.

Catheter ablation of persistent atrial fibrillation in a patient with cor triatriatum sinister demonstrating a total common trunk of the pulmonary vein.

A 57-year-old male with persistent atrial fibrillation (AF) was referred for catheter ablation. Multidetector computed tomography (MDCT) revealed that a membrane divided the left atrium into two chambers, thus indicating the presence of cor triatriatum sinister. A 3D image reconstructed by MDCT showed that the accessory atrium received the left common and the right side PVs, as if it were a total common trunk, and this then flowed into the main atrium. After isolation of the pulmonary vein and posterior wall from the left atrium, AF could not be induced by any programmed pacing. The patient has remained free from AF during the 1 year of follow-up.

Paradoxical responses to pacing maneuvers differentiating atrioventricular node reentrant tachycardia and junctional tachycardia.

A 40-year-old female presented at our hospital because of heart palpitations. During an electrophysiological study, atrioventricular (AV) conduction showed dual AV nodal physiology. Three types of supraventricular tachycardia (SVT) were induced. The initiation of SVT was reproducibility dependent on a critical A-H interval prolongation. An early premature atrial contraction during SVT repeatedly advanced the immediate His potential with termination of the tachycardia, indicating AV node reentrant tachycardia (AVNRT). However, after atrial overdrive pacing during SVT without termination of the tachycardia, the first return electrogram resulted in an AHHA response, consistent with junctional tachycardia. The mechanism of paradoxical responses to pacing maneuvers differentiating AVNRT and junctional tachycardia was discussed.

Percutaneous retrieval of a radiolucent anchoring sleeve embolized in pulmonary artery during pacemaker implantation.

An 85-year-old female presented to our institution with symptomatic sick sinus syndrome. During pacemaker implantation, an anchoring sleeve in the right ventricular lead was embolized in the left pulmonary artery. Although the anchoring sleeve was radiolucent, digital subtraction angiography revealed an angiographic filling defect in the lower branch of the left pulmonary artery, and a snare catheter enabled the anchoring sleeve to be grasped and extracted.

Filling defects of the left atrial appendage on multidetector computed tomography: their disappearance following catheter ablation of atrial fibrillation and the detection of LAA thrombi by MDCT.

Filling defects of the left atrial appendage (LAA) on multidetector computed tomography (MDCT) are known to occur, not only due to LAA thrombi formation, but also due to the disturbance of blood flow in the LAA of patients with atrial fibrillation (AF). The purpose of this study was to evaluate the impact of the maintenance of sinus rhythm via ablation on the incidence of LAA filling defects on MDCT in patients with AF. A total of 459 consecutive patients were included in the present study. Prior to ablation, MDCT and transesophageal echocardiography (TEE) were performed. AF ablation was performed in patients without LAA thrombi confirmed on TEE. The LAA filling defects were evaluated on MDCT at 3 months after ablation. LAA filling defects were detected on MDCT in 51 patients (11.1 %), among whom the absence of LAA thrombi was confirmed in 42 patients using TEE. The LAA Doppler velocity in patients with LAA filling defects was lower than that of patients without filling defects (0.61 ± 0.19 vs. 0.47 ± 0.21 m/s; P < 0.0001). The sensitivity, specificity and negative predictive value of MDCT in the detection of thrombi were 100, 91 and 100 %, respectively. No LAA filling defects were observed on MDCT at 3 months after ablation in any of the patients, including the patients in whom filling defects were noted prior to the procedure. MDCT is useful for evaluating the presence of LAA thrombi and the blood flow of the LAA. The catheter ablation of AF not only suppresses AF, but also eliminates LAA filling defect on MDCT suggesting the improvement of LAA blood flow.

Influence of the concomitant use of heparin on the effects of warfarin during catheter ablation for atrial fibrillation.

Warfarin is widely used to perform catheter ablation for atrial fibrillation (AF). Heparin is usually administered during this procedure to prevent thromboembolic events, while protamine is used to reduce the incidence of bleeding complications. The purpose of this study was to investigate the influence of heparin and protamine administration on the effects of warfarin and its safety. The subjects included 226 AF patients (206 males, 54.9 ± 9.1 years, paroxysmal/persistent AF: 118/108) undergoing AF ablation with the discontinuation of warfarin administration over 2 days. Heparin was administered to achieve an activated clotting time (ACT) above 300 s during the procedure. Several parameters of the coagulation status, including the prothrombin time international normalized ratio (PT-INR) and ACT values, measured immediately before and after protamine infusion were compared. The mean value of PT-INR prior to ablation was 1.9 ± 0.6. At the end of the procedure, the mean ACT and PT-INR values were 348.0 ± 52.9 and 2.9 ± 0.7, respectively. Following the infusion of 30 mg of protamine, both the ACT and PT-INR values significantly decreased, to 159.6 ± 31.0 (p < 0.0001) and 1.6 ± 0.3 (p < 0.0001), respectively. No cases of symptomatic cerebral infarction were observed, although femoral hematomas developed in 17 (7.5 %) of the patients without further consequence. The concomitant use of heparin augments the effect of warfarin. Meanwhile, protamine administration immediately reverses both the ACT and PT-INR, indicating the applicability of protamine for AF ablation in patients under the mixed administration of heparin and warfarin.

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

AIMS: Although 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. METHODS AND RESULTS: Of 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. CONCLUSION: Catheter 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.

The effect of open-irrigated radiofrequency catheter ablation of atrial fibrillation on left atrial pressure and B-type natriuretic peptide.

BACKGROUND: Open-irrigated radiofrequency catheter ablation (oiRFA) of atrial fibrillation (AF) imposes a volume load and risk of pulmonary edema. We sought to assess the effect of volume administration during ablation on left atrial (LA) pressure and B-type natriuretic peptide (BNP). METHODS: LA pressure was measured via transseptal sheath at the beginning and end of 44 LA ablation procedures in 42 patients. BNP plasma levels were measured before and after 10 procedures. RESULTS: A median of 3,255 (interquartile range [IQR], 2,014)-mL saline was administered during the procedure. During LA ablation, the median fluid balance was +1,438 (IQR, 1,109) mL and LA pressure increased by median 3.7 (IQR, 5.9) mm Hg (P < 0.001). LA pressure did not change in the 19 procedures with furosemide administration (median ΔP = -0.3 [IQR, 7.1] mm Hg, P = 0.334). The correlation of LA pressure and fluid balance was weak (rs = 0.383, P = 0.021). BNP decreased in all four procedures starting in AF or atrial tachycardia and then converting to sinus rhythm (P = 0.068), and increased in all six procedures starting and finishing in sinus rhythm (P = 0.028). After ablation, symptomatic volume overload responding to diuresis occurred in three patients. CONCLUSIONS: A substantial intravascular volume load during oiRFA can be absorbed with little change in LA pressure, such that LA pressure is not a reliable indicator of the fluid balance. Subsequent redistribution of the volume load imposes a risk after the procedure. Conversion to sinus rhythm may improve ability to acutely accommodate the volume load.

Diagnosis and ablation of multiform fascicular tachycardia.

INTRODUCTION: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies. METHODS AND RESULTS: Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF. CONCLUSIONS: Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated.

Cardiac tamponade as an independent condition affecting the relationship between the plasma B-type natriuretic peptide levels and cardiac function.

Plasma B-type natriuretic peptide (BNP) is finely regulated by the cardiac function and several extracardiac factors. Therefore, the relationship between the plasma BNP levels and the severity of heart failure sometimes seems inconsistent. The purpose of the present study was to investigate the plasma BNP levels in patients with cardiac tamponade and their changes after pericardial drainage. This study included 14 patients with cardiac tamponade who underwent pericardiocentesis. The cardiac tamponade was due to malignant diseases in 13 patients and uremia in 1 patient. The plasma BNP levels were measured before and 24-48 h after drainage. Although the patients reported severe symptoms of heart failure, their plasma BNP levels were only 71.2 ± 11.1 pg/ml before drainage. After appropriate drainage, the plasma BNP levels increased to 186.0 ± 22.5 pg/ml, which was significantly higher than that before drainage (P = 0.0002). In patients with cardiac tamponade, the plasma BNP levels were low, probably because of impaired ventricular stretching, and the levels significantly increased in response to the primary condition after drainage. This study demonstrates an additional condition that affects the relationship between the plasma BNP levels and cardiac function. If inconsistency is seen in the relationship between the plasma BNP levels and clinical signs of heart failure, the presence of cardiac tamponade should therefore be considered.

Improvement of atrioventricular conduction following catheter ablation of atrioventricular nodal reentry tachycardia in a patient with a prolonged PR interval.

We herein present the case of a 60-year-old male with narrow QRS tachycardia who had a remarkable PR prolongation during sinus rhythm. The tachycardia was diagnosed as a slow-fast atrioventricular nodal reentry tachycardia. Slow pathway ablation was performed after the confirmation of the presence of an antegrade fast pathway. Following the elimination of the slow pathway, the PR and atrio-His intervals became shortened from 470 and 420 to 170 and 120 ms, respectively. Moreover, the improvement of atrioventricular conduction after the slow pathway ablation lasted for at least 34 months.

QRS characteristics fail to reliably identify ventricular tachycardias that require epicardial ablation in ischemic heart disease.

OBJECTIVES: We tested proposed algorithms for idiopathic and nonischemic tachycardias for their ability to identify epicardial LV-VT origins. BACKGROUND: Several ECG features have been reported to identify epicardial origins for left ventricular tachycardias (LV-VTs) in the absence of myocardial infarction. Only limited data exist in postinfarction patients. METHODS: The QRS features of 24 VTs that were ablated from the epicardium and 39 left ventricular VTs ablated from the endocardium were retrospectively analyzed for various 12-lead ECG features previously reported. RESULTS: No ECG feature consistently predicted an epicardial LV-VT origin in infarct-related tachycardias, with epicardial VTs showing slightly longer QRS durations (189 ± 32 ms in epicardial vs 179 ± 37 ms in endocardial, P = 0.28). Pseudo-delta duration was 38 ± 27 versus 47 ± 27 ms (P = 0.2), intrinsicoid deflection time 93 ± 35 versus 86 ± 32 ms (P = 0.4), shortest RS 97 ± 38 versus 99 ± 32 ms (P = 0.77), and median deflection index 0.82 ± 0.25 versus 0.87 ± 0.22 (P = 0.43). The finding of a Q wave in lead I and the absence of a Q wave in the inferior leads failed to predict an epicardial origin in superior LV-VT sites. Q waves in any inferior lead and aVR/aVL-ratio<1 were not specific for an epicardial origin in inferior sites (all P = ns). Furthermore, all inferior LV-VTs showed a Q wave in the inferior leads which correlated with pre-existing Q-waves in sinus rhythm (P = 0.045). CONCLUSION: Proposed 12-lead ECG features for differentiation of epicardial versus endocardial sites for nonischemic LV-VTs do not reliably identify VTs that require ablation from the epicardium. Endocardial mapping should be the first approach to catheter ablation for VTs in patients with ischemic heart disease.

Substrate modification by pulmonary vein isolation and left atrial linear ablation in patients with persistent atrial fibrillation: its impact on complex-fractionated atrial electrograms.

UNLABELLED: PV and Linear Ablation for CFAEs. INTRODUCTION: 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. METHODS AND RESULTS: A total of 40 consecutive PsAF patients (age: 54 ± 10 years, 39 males) who underwent catheter ablation were enrolled in this study. Linear ablation of both roofline between the right and left superior PVs and the mitral isthmus line joining from the mitral annulus to the left inferior PV were performed following PV isolation during AF. High-density automated CFAE mapping was performed using the NAVX, and maps were obtained 3 times during the procedure (prior to ablation, after PV isolation, and after linear ablations) and were compared. PsAF was terminated by ablation in 13 of 40 patients. The mean total LA surface area and baseline CFAEs area were 120.8 ± 23.6 and 88.0 ± 23.5 cm(2) (74.2%), respectively. After PV isolation and linear ablations in the LA, the area of CFAEs area was reduced to 71.6 ± 22.6 cm(2) (58.7%) (P < 0.001) and 44.9 ± 23.0 cm(2) (39.2%) (P < 0.001), respectively. The LA linear ablations resulted in a significant reduction of the CFAEs area percentage in the region remote from ablation sites (from 56.3 ± 20.6 cm(2) (59.6%) to 40.4 ± 16.5 cm(2) (42.9%), P < 0.0001). CONCLUSION: Both PV isolation and LA linear ablations diminished the CFAEs in PsAF patients, suggesting substrate modification by PV and linear ablations. (J Cardiovasc Electrophysiol, Vol. 23, pp. 962-970, September 2012).

Relation of high-pass filtered unipolar electrograms to bipolar electrograms during ventricular mapping.

BACKGROUND: A filtered bipolar electrogram (EG) amplitude <1.5 mV is a robust indicator of relatively dense scar, but is influenced by the wavefront direction. Unipolar recordings are not subject to directional influence. We hypothesized that high-pass filtered unipolar EGs would provide similar information to bipolar EGs, without potential errors related to wavefront direction. METHODS: Simultaneous bipolar filtered at 30-500 Hz and unipolar (high-pass filtered at 30 Hz) signals were recorded during ventricular voltage maps in 24 patients (group A). In five subsequent patients, low voltage surface areas were compared in electroanatomic maps (group B). RESULTS: Of 2,789 mapping points in group A, filtered unipolar EG amplitude correlated well with bipolar EG amplitude. Agreement of filtered unipolar recordings in classifying sites as >1.5 mV or <1.5 mV with bipolar EG amplitude was 83%. Discordance was due to unipolar > bipolar amplitude at 83% of the discordant sites, consistent with possible reduction of bipolar amplitude due to direction dependence. Discordance was more frequent during epicardial than endocardial mapping. Double potentials were more frequently observed in bipolar than in unipolar recordings (3.2% vs 1.8%, P < 0.0001). In group B, the mean low-voltage surface area (<1.5 mV) was 70.1 ± 48.9 cm(2) for bipolar and 61.3 ± 52.2 cm(2) for filtered unipolar EG maps. CONCLUSION: Direction dependent effects on bipolar EG amplitude may influence the identification of substrate for arrhythmias. High-pass filtered unipolar EGs might be a reasonable alternative to bipolar recordings for creation of voltage maps.

Real-time dominant frequency analysis of the pulmonary vein in patients with paroxysmal atrial fibrillation.

BACKGROUND: Paroxysmal atrial fibrillation (PAF) can be treated with pulmonary vein isolation (PVI). A spectral analysis can identify sites of high-frequency activity during atrial fibrillation (AF). We investigated the role of the PVs on AF perpetuation by dominant frequency (DF) analysis. METHODS: Thirty-one consecutive patients with PAF who underwent PVI were included in the prospective study. DF was calculated in each of the PVs, 16, five, and five sites in the left atrium, the coronary sinus, and the right atrium, respectively. In patients presenting sinus rhythm at the baseline, AF was induced by pacing. The PVs were then divided into two groups; PVs demonstrated the highest DF (HDF-PV) and others. RESULTS: One patient was excluded from the analysis because sustained AF could not be induced. AF was terminated in 43.3% (13/30) of patients during ablation. Of 92 PVs isolated during AF, 30 and 62 PVs were classified into the HDF-PV and others, respectively. PAF was more frequently terminated by the HDF-PV isolation compared to the others (33.3% [10/30] vs 4.8% [3/62], P = 0.0004). Interestingly, nine of the 30 HDF-PVs showing the highest DF among all 30 regions, including extra PVs, led to AF termination in 88.9% (eight out of nine) of cases. Moreover, the HDF-PVs isolation resulted in a greater AF cycle length prolongation than the other PVs isolation (12.1±5.0 vs 2.7±7.6 ms, P = 0.007). CONCLUSION: Termination of PAF was more frequently observed during ablation of the PVs with the highest DF. The PV showing high DF played an important role in the maintenance of PAF.

Identification of a conduction gap of the mitral isthmus by using a novel high-density mapping catheter.

Peri-mitral atrial flutter, which is a type of macroreentrant atrial tachycardia circulating around the mitral annulus, was terminated with the guidance of the high-density mapping catheter. A 72-year-old woman with atrial fibrillation and atrial tachycardia presented with symptoms of congestive heart failure. The recurrent peri-mitral atrial flutter following the initial catheter ablation for atrial tachycardia and atrial fibrillation was terminated by radiofrequency application on the gap that was identified using a novel high-density mapping catheter.