Mapping and ablation of left atrial roof-dependent tachycardias using an ultra-high resolution mapping system.

BACKGROUND: Left atrial roof-dependent tachycardias (LARTs) are common macroreentrant atrial tachycardias (ATs). We sought to characterize clinical LARTs using an ultra-high resolution mapping system. METHODS: This study included 22 consecutive LARTs in 21 patients who underwent AT mapping/ablation using Rhythmia systems. RESULTS: Three, 13, 4, and 2 LART patients were cardiac intervention naïve (Group-A), post-roof line ablation (Group-B), post-atrial fibrillation ablation without linear ablation (Group-C), and post-cardiac surgery (Group-D), respectively. The mean AT cycle length was 244 ± 43 ms. Coronary sinus activation was proximal-to-distal or distal-to-proximal in 16 (72.7%) ATs. The activation map revealed 13 (59.1%) clockwise and 9 (40.9%) counter-clockwise LARTs. A 12-lead synchronous isoelectric interval was observed in 10/19 (52.6%) LARTs. The slow conduction area was identified on the LA roof, anterior/septal wall, and posterior wall in 18, 6, and 2 ATs, respectively. Twenty concomitant ATs among 13 procedures were also eliminated, and peri-mitral AT coexisted in 7 of 9 non-group-B patients. In group-B, the conduction gap was predominantly located on the mid-roof. Sustained LARTs were terminated by a single application and linear ablation in 6 (27.3%) and 9 (40.9%), while converting to other ATs in 7 (31.8%) LARTs. Complete linear block was created without any complications in all, however, ablation at the mid-posterior wall was required to achieve block in 4 (18.2%) procedures. During 14.0 (6.5-28.5) months of follow-up, 17 (81.0%) and 19 (90.5%) patients were free from any atrial tachyarrhythmias after single and last procedures. CONCLUSIONS: The LART mechanisms were distinct in individual patients, and elimination of all concomitant ATs was required for the management.

High-Resolution Mapping and Ablation of Atrial Tachycardias Involving the Lateral Left Atrium.

Background The lateral left atrium (LA) is often associated with atrial tachycardia (AT) because of its complex anatomy. We sought to characterize ATs associated with the lateral LA, including the posterolateral mitral isthmus (MI) and left atrial ridge. Methods and Results Twenty-eight lateral LA-associated ATs were mapped with high-resolution mapping systems and entrainment pacing. The vein of Marshall was mapped with a 1.8-Fr mapping catheter when possible. ATs were associated with the posterolateral MI in 18 ATs (14 perimitral, 3 small reentry, and 1 focal AT). All patients had undergone MI area ablation, and all ATs were successfully eliminated. During 27.0 (interquartile range, 10.5-40.0) months of follow-up, all were free from any atrial tachyarrhythmias, with 3 patients on antiarrhythmics. Of 10 ATs involving the ridge or Marshall bundle, 3 were ridge related, 3 were Marshall bundle related based on vein of Marshall mapping, and 1 was a persistent left superior vena cava related AT. All 7 patients had undergone MI linear ablation. The critical isthmus was in the LA-ridge junction or the LA-Marshall bundle junction. Bidirectional conduction block between the LA and ridge or Marshall bundle was created. Two patients had the critical isthmus in the other area. The remaining patient had micro-reentry in the ridge. All 10 ATs were terminated during ablation at the critical isthmus. During 12.0 (5.2-31.7) months of follow-up, all were free from any atrial tachyarrhythmias, with 7 patients on antiarrhythmics. Conclusions Most ATs occurred after MI area ablation. An high resolution mapping-guided approach is highly effective for identifying the mechanism.

Features Suggesting Preferential Conduction in Pulmonary Artery Ventricular Arrhythmia for Identification of Successful Ablation Sites.

Radiofrequency catheter ablation (RFCA) for pulmonary artery ventricular arrhythmia (PAVA) can be difficult because of the occasional existence of PAVA with preferential conduction.This study described the characteristics of PAVA that demonstrate preferential conduction.We analyzed electrocardiographic and electrophysiological data from 8 patients found to have PAVAs with preferential conduction out of 183 patients (4.4%) with right ventricular outflow tract (RVOT) arrhythmias who underwent RFCA at our hospitals. The PAVA with preferential conduction were classified into two types. In type 1 PAVA, successful ablation sites (success-sites) exhibited discrete prepotentials with an isoelectric line, in which the activation time (AT) was ≥ 50 milliseconds. In type 2 PAVA, excellent pace mapping was achieved at two sites separated by ≥ 20 mm: one in the RVOT free wall and the other at the success-site in the pulmonary artery. Type 1 and 2 PAVA features were considered signs of a short and long preferential conduction pathway, respectively.There were four patients each with type 1 and 2 PAVA. Type 1 PAVA was distinguished by the isoelectric line at success-sites with the mean AT of 78 ± 25.1 milliseconds. In type 2 PAVAs, although the AT at RVOT sites was very short (18.5 ± 10.1 milliseconds), the AT at success-sites was longer than that at the RVOT by 42.3 ± 36.2 milliseconds. Type 2 PAVAs displayed distinct electrocardiogram (ECG) features (R wave in lead I, RR' in inferior leads, and transitional zone in V4) not found in typical PAVA ECGs.PAVA with preferential conduction can manifest in distinct ways on the ECG and intracardiac mapping. Knowledge of these features may facilitate successful RFCA of such PAVA cases.

Durability of a right superior pulmonary vein isolation after an inevitably interrupted single short freeze during cryoballoon ablation.

BACKGROUND: In cryoballoon ablation, applications for right superior pulmonary veins (RSPVs) inevitably need to be interrupted for some safety reasons. We retrospectively investigated the RSPV isolation durability after single interrupted short freezes. METHODS: Data from 30 patients who underwent repeat procedures 8.2 (4.1-13.8) months after an inevitably interrupted single short freeze (<180 s) for RSPVs during the index cryoballoon procedures were analyzed. It was interrupted by active deflation due to phrenic nerve injury (PNI) (Group 1: n = 14) or passive deflation due to a balloon temperature of -60°C (Group 2: n = 16). RESULTS: The freezing time was 145 (107-166) and 142 (127-160) s and nadir balloon temperature -50.7 ± 3.6 and -60°C in Groups 1 and 2, respectively. Pulmonary vein isolation was achieved after interrupted freezing in all except in one patient requiring touch-up ablation in Group 1. All PNI was asymptomatic and recovered during the follow-up. Eight/13 (61.5%) and 16/16 (100%) RSPVs were durable during the second procedure in Groups 1 and 2. In Group 1, the freezing time was significantly longer in durable than reconnected RSPVs (p = .032), and the optimal cutoff point for the freezing duration to predict the durability was 94.0 s (sensitivity 100%, specificity 60.0%). When the freezing time was ≥120 s, 80% of the RSPVs were durable. However, when the freezing time was ≤68 s, all RSPVs were reconnected. CONCLUSIONS: The feasibility of second cryoapplications for RSPVs should be discussed considering the freezing time of the interrupted initial applications in Group 1, however, it was not necessary in Group 2.

Individualized left anterior oblique projection based on pigtail catheter visualization facilitates leadless pacemaker implantation.

BACKGROUND: Pacemaker positioning on the right ventricular (RV) septum during implantation is conventionally conducted utilizing two fixed fluoroscopy angles, a 45° left anterior oblique (LAO) and 35° right anterior oblique projection. However, placement location can be suboptimal, especially for leadless pacemakers (LPMs). OBJECTIVE: To evaluate the safety and ease of LPM implantation using individualized LAO projection. METHODS: Consecutive patients undergoing LPM implantation were prospectively included. The angle of the RV septum was recorded for each patient by studying the angle at which an RV pigtail catheter (RV-PC) could be seen edge on. This was then used as the preferred LAO projection angle for that patient. We evaluated the success rate and safety of this method. We also compared the RV septum angle as measured by this method versus that measured by chest CT. RESULTS: Of the 31 patients (mean age 80.6 ± 7.0 years, 15 females), LPM implantation was successful in 30. The pacemaker was implanted on the RV septum in 29 and on the free wall in one. LPM implantation was abandoned for anatomical reasons in one. Complications were limited to a groin arteriovenous fistula and one deep vein thrombosis. The angle of RV septum as measured by pigtail catheter and chest CT was not significantly different (CT: 54.8 ± 6.0°, RV pigtail catheter: 52.9 ± 6.1°, P = .07). CONCLUSIONS: Using an RV-PC to determine the preferred angle of LAO projection facilitates differentiation between the RV septum and free wall, which in turn facilitates optimal LPM placement.

Superior vena cava isolation with 50 W high power, short duration ablation strategy.

INTRODUCTION: The optimal ablation strategy is unknown regarding a superior vena cava isolation (SVCI). This study aimed to examine the feasibility and safety and to analyze the lesion characteristics of the SVCI using high-power, short-duration (HPSD) ablation. METHODS AND RESULTS: A total of 100 patients underwent an index SVCI using HPSD (n = 50, HPSD group) or conventional lower-power and longer-duration (n = 50, LPLD group) ablation, using the Thermocool Smarttouch SF. In the HPSD group, ablation was performed with a power of 50 W for 7 s, and was limited to 4 s at the lateral segment close to the right phrenic nerve. The ablation setting used in the LPLD group was 20-25 W for 20-30 s and was limited to 10-20 W for 15-30 s at the lateral segment when diaphragmatic capture was seen. An electrical SVCI was achieved in all patients. The HPSD group required a significantly shorter procedure time (10.8 ± 3.2 vs. 14.8 ± 6.4 min; p < .01), shorter radiofrequency duration (49 ± 16 vs. 282 ± 124 s; p < .01), fewer lesions (8.3 ± 2.5 vs. 10.4 ± 4.4; p < .01), and lower ablation index (316 ± 38 vs. 356 ± 62; p < .001) than the LPLD group. The incidence of a postprocedural asymptomatic mild diaphragmatic elevation was comparable (2% in the HPSD group vs. 6% in the LPLD group; p = .61). CONCLUSION: The 50-W HPSD ablation strategy allowed for a successful, fast, and safe SVCI with the fewer ablation lesions and the lower ablation index.

Real-World Safety Profile of Atrial Fibrillation Ablation Using a Second-Generation Cryoballoon in Japan: Insight From a Large Multicenter Observational Study.

OBJECTIVES: This study sought to investigate the incidence and characteristics of the real-world safety profile of second-generation cryoballoon ablation (2nd-CBA) in Japan. BACKGROUND: Pulmonary vein isolation using second-generation cryoballoons is an accepted atrial fibrillation ablation strategy. METHODS: This multicenter observational study included 4,173 patients with atrial fibrillation (3,807 paroxysmal) who underwent a 2nd-CBA in 18 participating centers. The baseline data and details of all procedure-related complications within 3 months post-procedure in consecutive patients from the first case at each center were retrospectively collected. RESULTS: Adjunctive ablation after the pulmonary vein isolation was performed in 2,745 (65.8%) patients. Complications associated with the entire procedure were observed in 206 (4.9%) total patients, and in the multivariate analysis, the age (odds ratio: 1.015; 95% confidence interval: 1.001 to 1.030; p = 0.035) and study period were predictors. Air embolisms manifesting as ST-segment elevation and cardiac tamponade requiring drainage occurred in 63 (1.5%) and 15 (0.36%) patients, respectively. Six (0.14%) patients had strokes/transient ischemic attacks, among whom 5 underwent ablation under an interrupted anticoagulation regimen. No atrioesophageal fistulae occurred; however, 10 (0.24%) patients had symptomatic gastric hypomotility. Esophageal temperature monitoring did not reduce the incidence, and the incidence was significantly higher in patients with adjunctive posterior wall isolations or mitral isthmus ablation than those without (p = 0.004). Phrenic nerve injury occurred during the 2nd-CBA in 58 (1.4%) patients; however, all were asymptomatic and recovered within 13 months. One patient died of aspiration pneumonia. CONCLUSIONS: This study had a high safety profile of 2nd-CBA despite including the early experience and high rate of adjunctive ablation. Care should be taken for air embolisms during 2nd-CBA.

Mapping and ablation of clinical spontaneous perimitral atrial tachycardias using an ultra-high-resolution mapping system.

BACKGROUND: Perimitral atrial tachycardias (PMATs) are common atrial tachycardias (ATs), yet their mechanisms vary. OBJECTIVE: The purpose of this study was to characterize clinical spontaneous PMATs using an ultra-high-resolution (UHR) mapping system. METHODS: The study included 32 consecutive PMATs in 31 patients who had undergone AT mapping/ablation using a UHR mapping system. RESULTS: Six, 10, 11, and 5 PMATs occurred in cardiac intervention-naïve (group A), post-lateral/posterior mitral isthmus linear ablation (group B), post-atrial fibrillation ablation without mitral isthmus linear ablation (group C), and post-cardiac surgery (group D) patients, respectively. Group A patients tended to be older, more likely were female, and had sinus node or atrioventricular conduction disturbances more frequently. A 12-lead synchronous isoelectric interval was observed in 15 PMATs (46.9%). Coronary sinus activation was proximal to distal or distal to proximal except in 3 PMATs with straight patterns due to epicardial gaps. Left atrial anterior/septal wall (LAASW) low-voltage areas were smallest in group B. Slow conduction areas (SCAs) were identified in 26 PMATs (81.2%) and were located on the LAASW in all group A and group D patients. Conduction velocity in the SCAs was slowest in group B. In group B, all PMATs were terminated by single applications, and the gaps were located epicardially in 5 of 10 (50%). Anterior (n = 23) or lateral/posterior (n = 9) mitral isthmus linear block was successfully created without any complications in all. Twenty-five concomitant ATs among 18 patients (58.1%) also were eliminated. During a median of 20.0 (11.0-40.0) months of follow-up, 28 patients (90.3%) were free from any atrial tachyarrhythmias. CONCLUSION: An UHR mapping-guided approach with identification of the individual tachycardia mechanism should be the preferred strategy given the distinct and complex arrhythmia mechanisms.

A prospective multicenter study of direct comparison of feasibility and safety of pulmonary vein isolation using the minimally interrupted apixaban between second-generation cryoballoon and radiofrequency ablation of paroxysmal atrial fibrillation: J-HIT apixaban.

BACKGROUND: The feasibility and safety of pulmonary vein isolation (PVI) using cryoballoon (CB) for paroxysmal atrial fibrillation (PAF) with minimally interrupted apixaban has not fully explored. METHODS: In this multicenter, randomized prospective study, we enrolled patients with PAF undergoing CB or radiofrequency (RF) ablation with interrupted (holding 1 dose) apixaban. The primary composite end point consisted of bleeding events, including pericardial effusion and major bleeding requiring blood transfusion, or thromboembolic events at 4 weeks after ablation; secondary end points included early recurrence of AF and procedural duration. RESULTS: A total of 250 patients underwent PVI (125 assigned to the RF ablation and 125 assigned to the CB ablation). The primary end point occurred in 1 patient in the CB ablation group (0.8%; 90% confidence interval [CI], 0.04 to 3.70) and 3 patients in the RF group (2.4%, P = .622; risk ratio, 0333; 90% CI, 0.05 to 2.20). All events were pericardial effusion, all of whom recovered after pericardiocentesis. Early recurrence of AF occurred in 4 patients (3.2%) in the RF group and in 6 patients (4.8%) in the CB group (P = .749). The procedural duration was shorter in the CB group than that in the RF group (136.5 ± 39.9 vs 179.5 ± 44.8 min, P < .001). CONCLUSION: CB ablation with minimally interrupted apixaban was feasible and safe in patients with PAF undergoing PVI, which was equivalent to RF ablation.

Perfect pace-mapping with different latencies from adjacent sites in bilateral outflow tract leading to successful sequential unipolar ablation.

A 77-year-old man with frequent monomorphic ventricular premature contractions (VPCs) was referred for catheter ablation. Detailed mapping just above the pulmonary valve (PV) revealed tiny fragmented potentials earlier than the VPC onset. Perfect pace-mapping was obtained using high voltage pacing just above the PV and the left aortic sinus of Valsalva, whose stimulus-to-VPC latencies differed by 20 ms. While the ablation at the pulmonary valve could not completely eliminate the VPCs, unipolar sequential ablation on both sides of the outflow tracts led to their successful abolition that was guided by perfect pace-mapping.

Extent of Atrial Deformation in Catheter Ablation of Atrial Fibrillation.

Anatomical atrial distortion during catheter mapping and ablation has not been elucidated in atrial fibrillation (AF) ablation. This study aimed to characterize the regional anatomical distortion in common ablation areas according to different contact forces (CFs) with radiofrequency and cryoballoon catheters.Ten patients underwent distortion mapping with low (5-10 g) and high CFs (10-30 g) at the pulmonary vein (PV) antra, left atrial (LA) roof line, mitral isthmus line, cavotricuspid isthmus line, and superior vena cava (SVC)-right atrial (RA) junction. Fifteen patients underwent distortion mapping with a 28-mm second-generation cryoballoon surrounded by a decapolar catheter at each PV antrum following creating the LA geometry. High CFs distorted the PV antra as compared to low CFs and the extent was greater at the anterior PV aspect, and the catheter was located more inside the PVs. The inflated cryballoon stretched the PV surface in the postero-superior direction in the upper PVs and posterior direction in the lower PVs. High CFs as compared to low CFs distorted the LA roof and cavotricuspid isthmus in the postero-inferior and inferior directions, respectively, but not the mitral isthmus line even with deflectable sheaths. High CFs distended the SVC-RA junction as compared to low CFs, and the extent was greatest at the lateral side and smallest at the antero-septal side.Human atria significantly distend during radiofrequency and cryoballoon ablation, and there are regional heterogeneities of the extent of the distortion. This information might aid operators in performing safe and effective AF ablation procedures.

Long-term outcomes after second-generation cryoballoon ablation of paroxysmal atrial fibrillation - Feasibility of a single short freeze strategy without bonus applications.

BACKGROUND: A paucity of data exists about long-term outcomes after second-generation cryoballoon ablation (2nd-CBA), and the feasibility of short freeze strategies remains under debate. We assessed the long-term follow-up outcomes. METHODS: This study included 186 paroxysmal atrial fibrillation (PAF) patients (62 ± 11 years, 136 men) who underwent 2nd-CBAs with a 28-mm balloon and single 3-min freeze strategy without bonus applications. Fourteen-day consecutive monitoring was performed to detect early AF recurrences (ERAFs). RESULTS: Overall, 713/736(96.9%) PVs were isolated with CBs. The total number of applications/patient was 5.3 ± 1.5. The total procedure and fluoroscopic times were 79.9 ± 28.1 and 24.4 ± 14.2 min. Asymptomatic right phrenic nerve injury occurred in 11 patients, however, all recovered during the follow-up. A total of 76(41.7%) patients experienced ERAFs. During a median 45.0 [30.0-51.0] month follow-up, the single procedure AF freedom was 76.1, 73.5, 70.5, and 63.7% at 1, 2, 3, and 4 years, respectively. At a median of 7.0 [4.0-12.0] months after the initial procedure, 35 (18.8%) patients underwent second procedures, and 106/137 (77.4%) PVs were still isolated. The multiple procedure AF freedom was 91.7, 89.3, 86.8, and 81.3% at 1, 2, 3, and 4 years, respectively. A Cox's proportional hazards model determined that the presence of ERAF was associated with a greater risk of recurrence after the last procedure (Hazard ratio = 2.830; 95% confidence interval = 1.173-6.833; p = 0.021). The percentage of continuation of anticoagulation therapy after the initial procedure was 33.1, 23.5, 21.7, and 21.7% at 1, 2, 3, and 4 years, respectively. CONCLUSIONS: Our long-term follow-up data demonstrated the feasibility of a single short freeze strategy in PAF patients.

The mechanisms of recurrent atrial arrhythmias after second-generation cryoballoon ablation.

BACKGROUND: In patients with paroxysmal atrial fibrillation (PAF), 10%-15% of patients require repeat procedures after second-generation cryoballoon pulmonary vein isolation (CB-PVI). We sought to explore the mechanisms of recurrences after cryoballoon ablation. METHODS: The data of 122 PAF patients who underwent second procedures for recurrent arrhythmias 7.0 (4.0-12.0) months after the CB-PVI were analyzed. During second procedures, non-PV AF foci were explored with isoproterenol, adenosine, and repetitive cardioversions. RESULTS: In total, 378/487 (77.6%) PVs remained isolated, and reconnections were not observed in any PVs in 59 (48.4%) patients. PV reconnections were associated with recurrences in 38 (31.1%) patients, of whom 33 (86.8%) had reconnections of at least 1 upper PV. In 6 (4.9%) patients, non-PV AF foci were identified in the upper PV antra where cryoballoons cannot isolate but within the circumferential radiofrequency PVI line. Non-PV AF foci were identified in the superior vena cava, right atrial body, left atrial body, and atrial septum in 28 (23.0%), 18 (14.7%), 4 (3.3%), and 5 (4.1%) patients, respectively. Twelve (9.8%) patients had multiple non-PV AF foci. Four (3.3%), 3 (2.4%), and 8 (6.5%) patients underwent second procedures for atrioventricular nodal reentrant tachycardia, atrial flutter, and atrial tachycardias. During 16.0 (8.0-24.0) months of follow-up, freedom from any atrial arrhythmia at 1 year and 2 years after the second procedure was 79.2% and 60.6%. Nineteen (15.5%) patients had antiarrhythmic drug therapy at the last follow-up. CONCLUSIONS: Our study suggested that improvement in the upper PV PVI durability, eliminating arrhythmogenic superior vena cavae and coexisting atrial arrhythmias, and bonus cryoballoon applications at PV antra might improve the single procedure outcome in cryoballoon ablation.

Circulatory dynamics changes are an additional predictor of successful pulmonary vein isolation during cryoballoon ablation.

The association between circulatory dynamics changes during cryoballoon applications and a successful pulmonary vein isolation (PVI) is unknown. Seventy atrial fibrillation patients who underwent PVI with 28-mm second-generation cryoballoons and single 3-min freezes were included. Intra-procedural parameters including circulatory dynamics changes during cryoapplications, were compared between 113 successful applications (30 left superior PVs[LSPVs], 30 left inferior PVs[LIPVs], 25 right superior PVs[RSPVs], and 28 right inferior PVs[RIPVs]) and 47 failed applications (10 LSPVs, 9 LIPVs, 8 RSPVs, and 20 RIPVs). In all individual PVs, lower nadir balloon temperatures (MinTemps) and longer thawing times (ThawTimes) significantly predicted a successful PVI. In addition, greater systolic blood pressure drops following releasing the PV occlusion (SBP-drops) significantly predicted a successful right PV PVI, and longer elapse times during SBP-drops significantly predicted a successful RIPV PVI. Composite parameters incorporating MinTemps and ThawTimes, SBP-drops, and ThawTimes showed the highest area under the curve to predict a successful left PV (0.876 for LSPVs, 0.851 for LIPVs) and right PV (0.927 for RSPVs, 0.980 for RIPVs) PVI, respectively. If the ThawTime (≥ 30 s) and SBP-drop (≤ - 21 mmHg) cutoff values were achieved for the RIPVs, the positive predictive value was 100%. In contrast, if both criteria were not achieved for the RIPVs, the negative predictive value was 100%. In the second-generation cryoballoon PVI, the MinTemp and ThawTime were significantly associated with acute success for all four PVs. In addition, SBP-drops further improved the accuracy of predicting a successful right PV PVI, especially of the RIPV.

Predictors of durable pulmonary vein isolation after second-generation cryoballoon ablation with a single short freeze strategy - Different criteria for the best freeze of the 4 individual PVs.

BACKGROUND: Parameters predicting the second-generation cryoballoon pulmonary vein isolation (CB-PVI) durability of each individual PV have not been investigated. OBJECTIVE: We explored the PVI durability predictors after left superior (LS), left inferior (LI), right superior (RS), and right inferior (RI) PV CB-PVI. METHODS: Data from 101 consecutive patients who underwent repeat procedures 7.0 [4.5-10.0] months after index cryoballoon procedures with single short freeze strategies were analyzed. RESULTS: Among 369 PVs successfully isolated by cryoballoons with mean freezing times of 207 s, 82/94 (87.2%) LSPVs, 78/93 (83.9%) LIPVs, 80/98 (81.6%) RSPVs, and 63/84 (75.0%) RIPVs were durable. In the remaining 25 PVs requiring touch-up ablation, 20 (83.3%) PVs had reconnections. In analyzing all PVs together, lower nadir balloon temperature, faster freezing speed (FS), slower thawing speed (TS), and shorter time-to-isolation were significantly associated with higher PVI durability, however, all parameters significantly differed among the 4 individual PVs (p < 0.0001). In individual analyses, for the LSPV, faster FS to -40 °C predicted higher PVI durability, but younger patients more likely had reconnections. For the LIPV, faster FS to -30 °C predicted higher PVI durability. For the RSPV, a lower nadir temperature, faster FS (to -30 and -40 °C), slower TS (to 0 and 15 °C), shorter time-to-isolation, and smaller PV diameter predicted higher PVI durability. For the RIPV, a slower TS (to 0 and 15 °C) predicted higher PVI durability. CONCLUSIONS: The durability of the CB-PVI was high even with a single short freeze strategy. The parameters predicting the PVI durability differed among the 4 PVs, suggesting that best freeze criterion should be considered separately for each of the 4 PVs.

SVC Mapping Using an Ultra-High Resolution 3-Dimensional Mapping System in Patients With and Without AF.

OBJECTIVES: This study aimed to characterize the superior vena cava (SVC) sleeve in patients with and without atrial fibrillation (AF). BACKGROUND: A few studies have examined the morphological characteristics of atrial myocardial extensions into the human SVC using autopsied hearts. METHODS: Thirty-four patients with AF and 30 without AF underwent SVC mapping during sinus rhythm using ultra-high-resolution mapping. In 18 patients with AF, SVC isolation was added, and the SVC mapping was repeated. RESULTS: The median acquisition time was 7.7 min (interquartile range [IQR]: 5.5 to 11.2 min), and 2,478 data points (IQR: 1,620 to 3,350 data points) were automatically annotated. The electrically activated SVC sleeve length was asymmetric and longest at the anteroseptal SVC (27.0 to 28.0 mm) and shortest at the posterolateral SVC (22.0 to 23.0 mm). The sleeve length at each segment was similar in patients with and without AF, however, conduction time in the sleeve was significantly longer (76.1 ± 26.4 ms vs. 61.0 ± 19.1 ms; p = 0.036) and conduction block more frequently pre-existing in patients with AF than in those without (3 of 34 vs. 0 of 30; p = 0.047). The conduction velocity from sinus node was slower in upper direction (to SVC) than in other directions. Electrical SVC isolations were successfully achieved in all 18 patients without any complications. The conventional isolation line was a median of 20 mm (IQR: 13.9 to 29.0 mm) apart from and superior to the earliest activation sites during sinus rhythm. The isolated SVC sleeve length was longest at the septal SVC (median: 19.1 mm [IQR: 11.8 to 24.2 mm]) and shortest at the anterolateral SVC (median: 6.4 mm [IQR: 0 to 11.3 mm]). CONCLUSIONS: Ultra-high-resolution human SVC mapping demonstrated asymmetric SVC musculature sleeves and variations in the sleeve length in individual patients. Conduction disturbances were more prominent in patients with AF than in those without.

Early Tissue Reaction After Second-Generation Cryoballoon Ablation Evaluated with Intracardiac Echocardiography.

Radiofrequency energy applications immediately produce tissue edema. This study aimed to investigate the acute tissue reaction immediately after second-generation cryoballoon applications using 3-dimensional intracardiac echocardiography (ICE) imaging technology.This study consisted of 10 patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation (PVI) using second-generation cryoballoons. Ablation was performed with a single 3-minute freeze strategy and exclusively 28-mm balloons. The left atrial and right pulmonary vein (PV) antra geometries were created with 3-dimensional ICE technology before and immediately after the PVI.Out of 20 right PVs, 19 were isolated exclusively with cryoballoons, and one right inferior PV (RIPV) required touch-up ablation. All 10 right superior PVs (RSPVs) were isolated by single cryoballoon applications, and RIPVs were isolated by a mean of 1.2 ± 0.4 applications. The total application time was 171 ± 19 and 203 ± 71 seconds, and nadir balloon temperature was -56.0 ± 4.9 and -53.8 ± 5.4°C for the RSPVs and RIPVs, respectively. In all patients, diffuse wall thickening of the antra and ostium of the right PVs was observed as compared to baseline. The wall thickening was 0-0.25 mm in 3 patients, and 0.25-0.5 mm in the remaining 7. During the median follow-up of 13 [10.2-17.2] months, 8 (80%) patients were free from arrhythmia recurrences. Nine (90%) patients underwent repeat cardiac computed tomography at a median of 6.0 [4.5-12.0] months after the initial procedure, and no PV stenosis was observed in all.Tissue edema and wall thickening appeared in the human left atrium immediately after second-generation cryoballoon ablation.

Epicardial-endocardial breakthrough site ablation: Demonstration of alternative target for perimitral atrial tachycardia.

A 62-year-old man underwent the catheter ablation for persistent atrial tachycardia (AT) with a cycle length of 357 milliseconds. An ultrahigh resolution mapping revealed that this tachycardia was a clockwise perimitral AT despite the conduction was apparently blocked across the lateral mitral isthmus line both at the endocardium and within the coronary sinus. The AT was terminated by the single radiofrequency application at the site below the mitral isthmus line where the endocardial activation breakout was seen. This case suggests that the epicardial-endocardial conduction breakthrough site may be an alternative ablation target in a difficult ablation case of perimitral AT.