Optimization of Outflow-Tract Ventricular Arrhythmia Ablation Using a Universal Right Ventricle Model

To determine the factors that influence radiation exposure during repair of supracondylar humerus fractures. Medical records of almost 200 children with supracondylar fractures were retrospectively analyzed for variables correlated with fluoroscopy time and radiation dose as measures of radiation exposure. There was no statistically significant difference in fluoroscopy time (27 vs. 22s p = 0.345) or direct radiation dose (0.394 vs. 0.318mSv p = 0.290) between uniplanar and biplanar C-arm use. No statistically significant differences in fluoroscopy time or radiation dose were found for surgical technique, comorbid ipsilateral fractures, preoperative neurovascular compromise, or resident participation. There was a significant 8.3s increase in fluoroscopy time (p = 0.022) and 0.249mSv increase in radiation dose (p = 0.020) as the fracture type increased from II to III. An increase in one pin during CRPP resulted in a statistically significant 10.4s increase in fluoroscopy time and a 0.205mSv increase in radiation dose. There were significant differences between the physician with the lowest fluoroscopy time and radiation dose compared with the physicians with the two highest values for both fluoroscopy time and radiation dose (p < 0.01). We found no significant difference in direct radiation exposure or fluoroscopy time when comparing biplanar to uniplanar C-arm use, resident participation, preoperative neurovascular compromise, or for comorbid ipsilateral fractures. Both outcomes increased significantly as fracture type increased from II to III and as the number of pins used during CRPP increased. Both outcomes were significantly different between the surgeons performing CRPP.

Objective The purpose of this study was to analyze the clinical feature, electrophysiological characteristics and results of radiofrequency catheter ablation of 468 patients with idiopathic right ventricular outflow tract arrhythmia (IRVOTA) , and to explore the gender differences in ventricular arrhythmia originating from the right ventricular outflow tract (RVOT) and factors affecting the results of radiofrequency ablation. Methods We retrospectively reviewed 468 consecutive patients who underwent endocardiac electrophysiologic study and radiofrequency catheter ablation due to IRVOTA ventricular arrhythmia in Fuwai Hospital from February 2009 to January 2013. There were 185 male and 283 female patients. The electrophysiological characteristics and the incidence and the results of radiofrequency catheter ablation of ventricular arrhythmias originated from six different sites were analyzed. The multivariate Logistic regression analysis were used to analyze gender difference in factors affecting the results of radiofrequency catheter ablation. Results In our study, female patients (283) were more common than male patients (185, 60.5% vs.39.5%) . The sex distribution in each origin of ventricular arrhythmia was different. There were significantly more male patients than female patients in free wall origin (11.4% vs.6.0%, P=0.04) . In the case of epicardial origin, the percentage of male patients were also significantly higher than that of female patients (8.6% vs.4.2%, P=0.02) . There were little more female patients in the septal origin without significant difference (56.9% vs. 48.6%, P=0.057) . The acute success rate of ablation in female patients was significantly higher than that in male patients (92.2% vs. 84.9%, P=0.01) . Gender differences also existed in factors affecting the results of ablation. For female, epicardia origin (OR 6.41, 95%CI: 1.26-32.70, P=0.017) and RVOT-AO origin (OR 8.88, 95%CI: 2.15-36.67, P=0.002) were the independent factors of ablation failure. However, for male, epicardia origin (OR 12.17, 95%CI: 3.19-46.39, P<0.001) was the only independent factor of ablation failure. Conclusion There were gender differences in different origins of ventricular arrhythmia in IRVOTA and results of radiofrequency ablation have gender differences. Key words: Ventricular arrhythmia; Right ventricular outflow tract; Gender; Radiofrequency catheter ablation

Funding Acknowledgements Type of funding sources: None. Background During electrophysiology (EP) procedures, fluoroscopy imaging is employed to visualise catheters position in real-time. However, ionizing radiation is a health hazard to both the patient and operator. In recent years, the use of electroanatomical mapping systems and operator adoption of low-fluoro workflows has allowed a reduction of radiation exposure. The aim of this study was to assess the evolution of fluoroscopy time (FT) in EP procedures, using conventional technique or an electroanatomical mapping system (EMS). Methods A retrospective analysis of consecutive EP procedures performed at a tertiary centre between September 2018 and October 2020 was conducted. The procedures were divided in 3 tertiles according to date (T1, T2 and T3), with T3 corresponding to the most recent interventions. Procedural duration, FT, use of EMS, radiofrequency time (RT), acute ablation success and procedural complications were examined. Results A total of 615 procedures were analysed: atrioventricular node reentry tachycardia (AVNRT) – n = 144, accessory pathways (AP) – n = 83, typical atrial flutter – n = 106, atrial fibrillation (AF) ablation with radiofrequency (RF) – n = 61, AF ablation with cryoballoon – n = 92, ablation of ventricular arrhythmias – n = 53, and 75 miscellaneous procedures (including atrioventricular node ablation, left atrial flutter ablation and cardioneuroablation). Mean age was 54.6 ± 18.2 years with 59.4% male sex patients. An EMS was used in 75% of the procedures, without significant differences between tertiles. A progressive reduction in median FT was observed over the tertiles (T1 6.3 min, interquartile range [IQR] 2.9-13.6; T2 5.4 min, IQR 2.1-12.0, and T3 3.1 min, IQR 1.2-7.2, Figure 1), and a statistical significant difference was found when comparing T1 to T3 (p &amp;lt; 0.001) and T2 to T3 (p &amp;lt; 0.001). The decrease in FT was observed throughout the study period for all different EP procedures (Figure 2). The number of procedures with zero fluoroscopy had gradually increased (T1 6.1%, T2 8.5% and T3 14.1%; T1 vs. T3 p &amp;lt;0.01). Younger patients (&amp;lt;20 years) were submitted to low fluoroscopy doses with a significant decrease over tertiles (T1 1.2 min, IQR 0.0-4.3; T2 0.9 min, IQR 0.0-2.5; T3 0.0, IQR 0.0-2.2, T1 vs.T3 p &amp;lt; 0.001). No significant difference in procedural duration, RT, acute procedural success or complication rate were noted between tertiles. Conclusion Reduction in radiation exposure can be achieved without compromising duration, safety and effectiveness of the procedure. The commitment of operators to reduce radiation exposure using 3D mapping technology can lead to a significant decrease in the use of fluoroscopy. Abstract Figure. Fluoroscopic time analysis

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare.This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin.Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm.The findings could be strong evidence for a preferential conduction via the myocardial fibers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

Introduction: Symptomatic outflow tract ventricular arrhythmia (OTVA), including ventricular tachycardia and premature ventricular complexes, can be readily treated with catheter ablation. Outflow tract anatomy is complex and differentiating aortic, pulmonary and subvalvular origin is important for planning approach to mapping and ablation. We investigated whether surface ECG characteristics of OTVA can accurately discriminate between right coronary cusp (RCC), peri-pulmonic valve (PV) and right ventricular outflow tract (RVOT) origin. Methods: Thirty-six consecutive patients (mean age 41±14 years, 13 male) undergoing catheter ablation for OTVA were studied. Site of OTVA origin were determined from intracardiac electrogram tracings, electroanatomical maps and ablation reports. Observers blinded to these results manually measured PVC waveform amplitude and duration from standard 12-lead ECG tracings. Measurements with highest diagnostic performance were modelled into an algorithm designed to discriminate between predefined sites of origin within the outflow tract. Results: Sites of successful ablation were anterior RVOT (n=6), posterior RVOT (n=4), PV (≤1cm below, at or above pulmonary valve, n=18) and RCC (n=8). RCC origin was best discriminated by lead I R-wave ≥ 1.5 mV AND V1 R-wave ≥2.0mV (PPV 39%, NPV 94%, accuracy 67%). Posterior RVOT origin was best discriminated by lead I R/(R+S) ≥ 0.1 AND V1 R-wave > 0mV (PPV 33%, NPV 96%, accuracy 81%). Anterior RVOT origin was best discriminated by V1 R-wave = 0mV AND aVR/aVL S-wave ratio > 1 (PPV 100%, NPV 94%, accuracy 94%). Origin from PV was best discriminated by lead II/III R-wave ratio ≤0.95 OR lead I R/(R+S) < 0.08 (PPV 68%, NPV 86%, accuracy 75%). Sequential algorithmic application of these criteria resulted in an overall accuracy of 80% in predicting site of OTVA origin. Conclusions: Application of simple surface ECG criteria in sequential algorithmic fashion can discriminate between coronary cusp, peri-pulmonic and RVOT origin of outflow tract ventricular arrhythmia.

Safety of radiofrequency catheter ablation without coronary angiography in aortic cusp ventricular arrhythmias.

Three-dimensional electroanatomic mapping (EAM) systems reduce radiation exposure when radio frequency catheter ablation (RFCA) procedures are performed by well-trained senior operators. Given the steep learning curve associated with complex RFCA, trainees and their mentors must rely on multiple imaging modalities to maximize safety and success, which might increase procedure and fluoroscopy times. The objective of the present study is to determine if 3-D EAM (CARTO and ESI-NavX) improves procedural outcomes (fluoroscopy time, radio frequency time, procedure duration, complication, and success rates) during CA procedures as compared to fluoroscopically guided conventional mapping alone in an academic teaching hospital. We analyzed a total of 1070 consecutive RFCA procedures over an 8-year period for fluoroscopic time stratified by ablation target and mapping system. Multivariate logistic regression and adjusted odds ratios were calculated for each variable. No statistically significant differences in acute success rates were noted between conventional and 3-D mapping cases [CARTO (p = 0.68) or ESI-NavX (p = 0.20)]. Moreover, complication rates were also not significantly different between CARTO (p = 0.23) and ESI-NavX (p = 0.53) when compared to conventional mapping. Procedure, radio frequency, and fluoroscopy times were significantly longer with CARTO and ESI-NavX versus conventional mapping [fluoroscopy time: CARTO, 28.3min; ESI, 28.5min; and conventional, 24.3min; p < 0.001)]. The use of 3-D EAM systems during teaching cases significantly increases radiation exposure when compared with conventional mapping. These findings suggest a need to develop alternative training strategies that enhance confidence and safety during catheter manipulation and allow for reduced fluoroscopy and procedure times during RFCA.

Reasons for failed ablation for idiopathic right ventricular outflow tract-like ventricular arrhythmias

Background: Multipolar, phased radiofrequency (RF) catheter ablation (PVAC) has been associated with reduced procedural times compared to traditional RF. We performed a multicenter study to assess the efficacy and efficiency of using this catheter. Methods: This is a multicenter, sequential, prospective, cohort study between 2012 to 2016 in 6 tertiary care centers (NCT01562912). Patients were enrolled if they had symptomatic, paroxysmal AF (less than 7 days) refractory to at least one antiarrhythmic medication. Patients were enrolled in a 2:1 ratio of PVAC (group A) to control point-by-point RF with 3D mapping (group B). ECG and 48 hour Holter monitor were used to assess patients at 3, 6, 9 and 12 months post-ablation follow up. Recurrence was defined as any atrial arrhythmia &gt;30 seconds excluding an initial 3 month blanking period. Results: Overall, 230 patients consisting of 162 males (70.4%) with mean age 57±11 years were analyzed. By Kaplan-Meier analysis, freedom from any atrial arrhythmia at 12 months was 49% and 69.2% in group A and B respectively (p=0.033) (Figure1). Among patients with recurrence, 14.7% (21) in group A and 7.7% (6) in group B had redo procedure within 12 month post procedure(p=0.12). Procedure time was significantly lower in Group A than Group B (P&lt;0.0001). There was no significant difference in fluoroscopy time between the two groups (p=0.49). Stroke was not reported in any of the patients. Pulmonary Embolism, occurred in 1.3% of patients in group B. Pericardial effusion occurred in 1.4% in group A and 2.6% in group B. Tamponade occurred in 3.8% of patients in group B. Conclusion: This study demonstrated that the PVAC catheter is associated with significantly reduced procedure times for AF ablation, however, AF recurrence rates may be higher than contemporary point-by-point RF ablation with 3D mapping technology.

See Article by Komatsu et al The left ventricular summit (LVS) is the most superior portion of the epicardial LV outflow tract and is a common site of origin of idiopathic ventricular arrhythmias (VAs).1,2 The LVS is anatomically bounded septally by the bifurcation between the left anterior descending and the left circumflex coronary arteries, and transected laterally by the great cardiac vein at the junction with the anterior interventricular vein.3 A proper knowledge of the specific anatomic boundaries within the LVS has substantial clinical relevance with respect to the mapping and ablation approach. The junction between the great cardiac vein and the anterior interventricular vein separates the LVS into an accessible region, lateral to the venous junction and remote from the bifurcation of the left main coronary artery and the epicardial fat around the atrioventricular groove, and an inaccessible region septal to the venous junction and in close proximity to the proximal left coronary arteries and epicardial fat. Although VAs arising from the accessible LVS are rarely problematic and usually can be mapped and ablated from the distal coronary venous system or directly via a percutaneous pericardial approach,2,4 VAs from the inaccessible region represent a major clinical challenge. Direct epicardial mapping of the inaccessible LVS via a percutaneous epicardial access is limited mainly by the presence of a thick layer of epicardial fat which effectively …

Veltmann C, Schimpf R, Steitner F, Hu D, Pfeiffer R, Borggrefe M, Wolpert C, Antzelevitch C. Electrocardiographic identification of SCN5A mutation carriers in a large European family. Europace Journal 2009, 11(Supplement 2), Abstract 34.Wijnmaalen AP, Van Der Geest RJ, Siebelink HJ, Kroft L, Bax JJ, Reiber JH, Schalij MJ, Zeppenfeld K. Integration of MRI derived 3D scar maps with electroanatomical mapping during catheter ablation of scar-related ventricular tachycardia late after myocardial infarction. Europace Journal 2009, 11(Supplement 2), Abstract 35.Algalarrondo VA, Dinanian SD, Juin CJ, Adams DA, Slama MS. Paroxystic AV block and prophylactic pacing in familial amyloid polyneuropathy. Europace Journal 2009, 11(Supplement 2), Abstract 36.# Electrocardiographic identification of SCN5A mutation carriers in a large European family {#article-title-2} Veltmann C, Schimpf R, Steitner F, Hu D, Pfeiffer R, Borggrefe M, Wolpert C, Antzelevitch C. Electrocardiographic identification of SCN5A mutation carriers in a large European family. Europace Journal 2009, 11(Supplement 2), Abstract 34.Wijnmaalen AP, Van Der Geest RJ, Siebelink HJ, Kroft L, Bax JJ, Reiber JH, Schalij MJ, Zeppenfeld K. Integration of MRI derived 3D scar maps with electroanatomical mapping during catheter ablation of scar-related ventricular tachycardia late after myocardial infarction. Europace Journal 2009, 11(Supplement 2), Abstract 35.Algalarrondo VA, Dinanian SD, Juin CJ, Adams DA, Slama MS. Paroxystic AV block and prophylactic pacing in familial amyloid polyneuropathy. Europace Journal 2009, 11(Supplement 2), Abstract 36.The loss-of-function SCN5A missense mutation E1784K leads to the Brugada and/or Long QT phenotype and to cardiac conduction disease. The aim of the present study was to perform a genotype-phenotype correlation in a large family with the E1784K mutation and to identify electrocardiographic markers capable of differentiating between mutation carriers and non-carriers. Methods: We screened a large 33-member European family. The work-up included the medical and family history (n=33), a baseline ECG (n=27), sodium blocker challenge (n=23) and genetic screening (n=27). Results: 27 members (28±15 years of age; 16 males, 11 females) were genotyped. In 17 of 27 patients (8 males, 9 females) a E1784K missense mutation was identified in SCN5A. Mutation carriers revealed significantly longer PR and QT intervals and QRS duration compared to non-carriers. (PQ: 195ms vs. 155ms, P<0.003; QT: 466ms vs. 415ms, P<0.0001, QRS: 100ms vs. 80ms; P<0.002). Using ROC analysis, QTc ≥ 445 ms was identified as a good predictor of a positive genotype (sensitivity 88%, specificity 100%). No patient showed a spontaneous Brugada type I ECG. 4 patients displayed a Brugada type II and III ECG. Out of 23 ajmaline tests 12 were positive, 8 negative und 3 were prematurely terminated due to QRS prolongation and premature ventricular contractions. All non-carriers revealed a negative ajmaline test (n=8). In 15 of 17 patients with positive genotype, ajmaline challenge was performed. 12 tests (80%) were positive and 3 tests were prematurely terminated. Conclusions: Our results indicate E1784K-SCN5A carriers have significantly longer PR, QT and QRS durations. 80% of mutation carriers and none of non-carriers display a Type I ST segment elevation characteristic of Brugada syndrome following challenge with sodium channel blockers. QTc interval ≥ 445 predicted the presence of the E1784K mutation. All non-carriers displayed normal ECG parameters. # Integration of MRI derived 3D scar maps with electroanatomical mapping during catheter ablation of scar-related ventricular tachycardia late after myocardial infarction {#article-title-3} Veltmann C, Schimpf R, Steitner F, Hu D, Pfeiffer R, Borggrefe M, Wolpert C, Antzelevitch C. Electrocardiographic identification of SCN5A mutation carriers in a large European family. Europace Journal 2009, 11(Supplement 2), Abstract 34.Wijnmaalen AP, Van Der Geest RJ, Siebelink HJ, Kroft L, Bax JJ, Reiber JH, Schalij MJ, Zeppenfeld K. Integration of MRI derived 3D scar maps with electroanatomical mapping during catheter ablation of scar-related ventricular tachycardia late after myocardial infarction. Europace Journal 2009, 11(Supplement 2), Abstract 35.Algalarrondo VA, Dinanian SD, Juin CJ, Adams DA, Slama MS. Paroxystic AV block and prophylactic pacing in familial amyloid polyneuropathy. Europace Journal 2009, 11(Supplement 2), Abstract 36.Background: The current used gold standard to guide substrate based ablation of scar-related ventricular tachycardia (VT) relies on electroanatomical endocardial and epicardial voltage mapping (EAM). Integration of the complex 3-dimensional (3D) scar geometry derived from contrast enhanced magnetic resonance imaging (CE-MRI) with EAM may provide supplementary substrate information. This study aimed to assess the feasibility of integrating CE-MRI derived data with EAM during radiofrequency catheter ablation (RFCA) of scar-related VT. Methods: 15 patients (14 male, 64±9yr) referred for RFCA of VT late after myocardial infarction underwent CE-MRI using a 1.5 T MRI system. Endocardial and epicardial contours of the CE-MRI were used to create 3D surface meshes of the left ventricle (LV), the aortic cusps and the left main (LM) origin. The vertices of the meshes were color coded based on the transmural extend of scar at a particular intramural location. Prior to ablation the MRI derived scar maps were imported into the CARTO-merge system. Bipolar endocardial EAM of the LV and aortic cusps were obtained and the LM location was marked. Areas with bipolar electrograms <1.5mV were defined as scar. Registration of the MRI derived scar maps and electroanatomical voltage maps was performed using the LM as landmark and the CARTO surface registration algorithm. Results: The average number of LV EAM points was 258±42. Merging of MRI derived scar data with voltage maps was successful in all patients with an average registration error of 3.8±0.6mm. There was a good agreement between regions of transmural scar defined by MRI and EAM. In 5 (33%) patients the subendocardial scar area identified by CE-MRI was larger than the scar area defined by EAM. Conclusions: Integration of MRI derived scar maps with EAM during VT ablation is feasible and accurate. CE-MRI derived scar maps identify intramural scar undetected by EAM and may provide important supplementary substrate information. # Paroxystic AV block and prophylactic pacing in familial amyloid polyneuropathy {#article-title-4} Veltmann C, Schimpf R, Steitner F, Hu D, Pfeiffer R, Borggrefe M, Wolpert C, Antzelevitch C. Electrocardiographic identification of SCN5A mutation carriers in a large European family. Europace Journal 2009, 11(Supplement 2), Abstract 34.Wijnmaalen AP, Van Der Geest RJ, Siebelink HJ, Kroft L, Bax JJ, Reiber JH, Schalij MJ, Zeppenfeld K. Integration of MRI derived 3D scar maps with electroanatomical mapping during catheter ablation of scar-related ventricular tachycardia late after myocardial infarction. Europace Journal 2009, 11(Supplement 2), Abstract 35.Algalarrondo VA, Dinanian SD, Juin CJ, Adams DA, Slama MS. Paroxystic AV block and prophylactic pacing in familial amyloid polyneuropathy. Europace Journal 2009, 11(Supplement 2), Abstract 36.Introduction: Familial amyloid polyneuropathy (FAP) is a dominantly inherited disease caused by mutated transthyretin. FAP cardiopathy is characterized by conduction disorders, denervation, and hypertrophic cardiomyopathy. Because of the risk of high degree atrioventricular (AV) block, prophylactic pacing can be suggested for high risk patients: in case of infra nodal AV block (HV interval > 70ms or between 60ms and 70ms with ECG abnormalities) or in case of unexplained syncope. By using pacing systems wich preserve physiological AV conduction, our purpose was to estimate prevalence of AV block and pacing dependance for high risk FAP patients. Methods: In a cohort of 29 FAP patients with conduction disorders leading to prophylactic pacing, we studied AV conduction using the AAI Safe R system (ELA medical). Datas were collected by using the Holter memories of pacemakers. Results: Patients were 50±15 years old and were followed during 13.7±11.9 months after pace maker insertion (12080 days cumulated). Before pace maker insertion, ECG was normal in 23% of cases. Electrophysiologic study showed 118±12ms for AH interval and 62±6ms for HV interval. Average percentage of ventricular pacing was 15±25%and 31±34% for atrial pacing. If 58% of patients (17/29) had less than 5% needs of ventricular pacing, we noted AV blocks episods for all patients but three (90%). Frequency of AV conduction disorders was 356±514 events per month (epm) and was distributed in 17±56 epm for type III AV block, 288±483 epm for type II AV block, 39±61epm for type I AV block and 1±4 for pauses. Percentage of ventricular pacing was positively correlated to frequency of AV block (R = 0.9, P<0.0001), to AH interval (R = 0.7, P = 0.003) and negatively to HV interval (R = -0.63, P = 0.007). During the study, sustained atrial arrhythmias occurred in two patients. No sustained ventricular arrhythmias were noted. Conclusion: Patients with FAP cardiopathy can present unpredictable paroxystic high degrees AV blocks. For patients with high risk of conduction disorders (HV interval >70ms, HV interval between 60ms and 70ms with ECG abnormalities or in case of unexplained syncope), prophylactic pacemaker insertion should be performed. Pacemaker features designed to promote spontaneous atrioventricular conduction allow a good AV conduction monitoring in FAP patients. Pre operative impairment of the nodal conduction is correlated to the rate of ventricular pacing with this stimulation mode.

Previous studies have reported the presence of subtle abnormalities in the right ventricular outflow tract (RVOT) in patients with apparently normal hearts and ventricular arrhythmias (VAs) from the RVOT, including the presence of low voltage areas (LVAs). This LVAs seem to be associated with the presence of ST-segment elevation in V1 or V2 leads at the level of the 2nd intercostal space (ICS). Our aim was to validate an electrocardiographic marker of LVAs in the RVOT in patients with idiopathic outflow tract VAs. A total of 120 patients were studied, 84 patients referred for ablation of idiopathic VAs with an inferior axis by the same operator, and a control group of 36 patients without VAs. Structural heart disease including arrhythmogenic right ventricular cardiomyopathy was ruled out in all patients. An electrocardiogram was performed with V1-V2 at the 2nd ICS, and ST-segment elevation ≥1 mm and T-wave inversion beyond V1 were assessed. Bipolar voltage map of the RVOT was performed in sinus rhythm (0.5-1.5 mV color display). Areas with electrograms <1.5 mV were considered LVAs, and their presence was assessed. We compared three groups, VAs from the RVOT (n = 66), VAs from the LVOT (n = 18) and Control group (n = 36). ST-elevation, T-wave inversion and left versus right side of the VAs were tested as predictors of LVAs, respective odds ratio (ORs) (95% confidence interval [CI]) and p values, were calculated with univariate logist regression. Variables with a p < .005 were included in the multivariate analysis. ST-segment elevation, T-wave inversion and LVAs were present in the RVOT group, LVOT group and Control group as follows: (62%, 17%, and 6%, p < .0001), (33%, 29%, and 0%, p = .001) and (62%, 25%, and 14%, p < .0001). The ST-segment elevation, T-wave inversion and right-sided VAs were all predictors of LVAs, respective unadjusted ORs (95% CI), p values were, 32.31 (11.33-92.13), p < .0001, 4.137 (1.615-10.60), p = .003 and 8.200 (3.309-20.32), p < .0001. After adjustment, the only independent predictor of LVAs was the ST-segment elevation, with an adjusted OR (95% CI) of 20.94 (6.787-64.61), p < .0001. LVAs were frequently present in patients with idiopathic VAs. ST-segment elevation was the only independent predictor of their presence.

Prediction of the chamber of origin in patients with outflow tract ventricular arrhythmias (OTVA) remains challenging. A clinical risk score based on age, sex and presence of hypertension was associated with a left ventricular outflow tract (LVOT) origin. We aimed to validate this clinical score to predict an LVOT origin in patients with OTVA. In a two-center observational cohort study, unselected patients undergoing catheter ablation (CA) for OTVA were enrolled. All procedures were performed using an electroanatomical mapping system. Successful ablation was defined as a ≥80% reduction of the initial overall PVC burden after 3 months of follow-up. Patients with unsuccessful ablation were excluded from this analysis. We included 187 consecutive patients with successful CA of idiopathic OTVA. Mean age was 52±15 years, 102 patients (55%) were female, and 74 (40%) suffered from hypertension. A LVOT origin was found in 64 patients (34%). A score incorporating age, sex and presence of hypertension reached 73% sensitivity and 67% specificity for a low (0-1) and high (2-3) score, to predict an LVOT origin. The combination of one ECG algorithm (V2 S/V3 R-index) with the clinical score resulted in a sensitivity and specificity of 81% and 70% for PVCs with R/S transition at V3 . The published clinical score yielded a lower sensitivity and specificity in our cohort. However, for PVCs with R/S transition at V3, the combination with an existing ECG algorithm can improve the predictability of LVOT origin.

Background Radiofrequency catheter ablation (RFCA) has good acute and long-term success rates in idiopathic and ischemic ventricular arrhythmia (VA). Drawbacks of the RFCA are reversibility of the edema and limited penetration of the RF energy into the tissue which explain a worse effectiveness in midmyocardial substrates. In comparison to RFCA, the lesions produced by ultra-low temperature cryoablation (ULTC) which uses near-critical nitrogen cryogen at -1960C can be both deeper and irreversible, depending on the duration of the freeze. Purpose We aimed to evaluate the acute effectiveness of a new ULTC technology for VA by examining post-interventional cardiac magnetic resonance images (CMR) with late gadolinium enhancement (LGE), as a part of multi-center Cryocure-VT study. Methods Between December 2022 and May 2023, we ablated 6 patients (age 63±16%; 5 male) with sustained VA and structural heart disease. Three patients had previous myocardial infarction; 1 cardiac sarcoidosis, 1 LMNA/C dilated cardiomyopathy and 1 post-myocarditis VA. LGE-CMR was available in all patients before the ULTC. At first, electro-anatomical mapping and VA induction were performed followed by ULTC using transseptal access. Each application consisted of freeze-thaw-freeze cycle with freeze duration at operator’s discretion based on manufacturer-recommended duration-depth curve. At the end, induction protocol was repeated to assess the acute success. Additionally, LGE-CMR was performed after ablation as an attempt to visualize the cryo-lesions. Results Median of 6 applications (IQR 4.75-7.5) of cryo-energy were applied per patient. Median procedure time was 180 min (IQR 97-180), and median fluoroscopy time of 20 min (IQR 15-26). Septal VA exits were detected in 3/6 patients; in 1 the exit was at aorto-mitral continuity; in 2 – basal inferior. After ablation, no VAs were inducible in 5/6 (83%) patients. The only patient with failure to ablate all VAs had fewer applications (n=4) and shorter freeze duration of 30 sec., as compared to the rest. Post-procedural CMR revealed new LGE with up to 75% transmurality in 5/6 patients; microvascular obstruction in 4/6 patients. Only LV edema, but no LGE was observed in the patient with shortest freeze time, who also had intra-hospital recurrence. No complications occurred. Conclusions Cryoablation of VA using a new ultra-low temperature technology is effective and safe to ablate VT even in patients with mid-septal substrates. New LGE in result of ULTCA can be observed in CMR and the lesions depth depends on the duration of application.

Objective The purpose of this study was to analyze the target distribution characteristics, the voltage characteristics, and electrophysiological characteristics of unipolar potential in right ventricular outflow tract(RVOT)ventricular arrhythmias(VA). We expected to optimize the diagnostic criteria of the ablation targets for RVOT VA. Methods One hundred and forty-six consecutive patients with VA originating from RVOT underwent radiofrequency catheter ablation(RFCA)in Zhongshan Hospital from June 2016 to August 2017 were studied.One hundred and fifty-three types of premature ventricular complexes(PVC)and 6 types of ventricular tachycardia(VT)were recorded during the procedure.We recorded 141 successful targets(ST)and 192 failed targets(FT). RVOT was divided into three parts by the detailed three-dimensional voltage mapping using the Carto system prior to the RFCA.The voltage on bipolar electrogram was defined as follows: amplitude 1.5 mV as . Results One hundred and thirty-four patients with 141 targets were successfully ablated, and 12 patients failed.In the ST group, ablation target was located in normal-voltage zone in 23 patients, in transitional-voltage zone in 95 patients, and low-voltage zone in 23 patients.There was no significant difference of the max slope of the descending limb(MSDL)between ST group and FT group.The local activation preceding time(LAPT)was earlier in ST group than that in FT group [(29.7±4.5)ms vs.(23.0±6.5)ms, P<0.001]. The interval of MSDL(IMSDL)was shorter in ST group than that in FT group [(11.80±10.39)ms vs.(21.64±11.83)ms, P=0.001]. The IMSDL and LAPT were both valuable predictive indexes for ST, whose area under curve(AUC) were 70.7% and 81.1%, respectively.A better predictive value could acquire when IMSDL and LAPT were combined used(AUC 89.3%, sensibility 75.8%, specificity 90.4%). Conclusions Pulmonary subvalves are the sites of RVOT VA.A better predictive value can be acquired when IMSDL and LAPT are combined. Key words: Ventricular premature complexes; Catheter ablation