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Introduction: Atrial fibrillation and atrial flutter originating from the donor s heart is a commonly reported complication post heart transplant. Atrial tachyarrhythmia originating from the recipient s heart, propagated through recipient‐to‐donor connections, is rare with only few cases reported in the literature; most reported cases from our review occur years post‐transplant. Case: A 47‐year‐old male presented with atrial tachycardia 6 months post heart transplant. Electrophysiologic study demonstrated atrial fibrillation originating from native heart and propagated through atrio‐atrial connections to the donor heart. This arrhythmia was successfully terminated with radiofrequency ablation. Conclusion: Atrio‐atrial connection between recipient and donor can form as early as a few months post heart transplant. Radiofrequency ablation appears to be an effective treatment for atrial fibrillation propagated through donor‐to‐recipient connections. [ABSTRACT FROM AUTHOR]

Introduction: Development of a rapid means to verify the ventricular tachycardia (VT) isthmus location from heart surface electrogram recordings would be a helpful tool for the electrophysiologist. Method: Myocardial infarction was induced in 22 canines by left anterior descending coronary artery ligation under general anesthesia. After 3–5 days, VT was inducible via programmed electrical stimulation at the anterior left ventricular epicardial surface. Bipolar VT electrograms were acquired from 196 to 312 recording sites using a multielectrode array. Electrograms were marked for activation time, and activation maps were constructed. The activation signal, or signature, is defined as the cumulative number of recording sites that have activated per millisecond, and it was utilized to segment each circuit into inner and outer circuit pathways, and as an estimate of best ablation lesion location to prevent VT. Results: VT circuit components were differentiable by activation signals as: inner pathway (mean: 0.30 sites activating/ms) and outer pathway (mean: 2.68 sites activating/ms). These variables were linearly related (p <.001). Activation signal characteristics were dependent in part upon the isthmus exit site. The inner circuit pathway determined by the activation signal overlapped and often extended beyond the activation map isthmus location for each circuit. The best lesion location estimated by the activation signal would likely block an electrical impulse traveling through the isthmus, to prevent VT in all circuits. Conclusions: The activation signal algorithm, simple to implement for real‐time computer display, approximates the VT isthmus location and shape as determined from activation marking, and best ablation lesion location to prevent reinduction. [ABSTRACT FROM AUTHOR]

Introduction: Multiple analysis techniques evaluate electrograms during atrial fibrillation (AF), but none have been established to guide catheter ablation. This study compares electrogram properties recorded from multiple right (RA) and left atrial (LA) sites. Methods: Multisite LA/RA mapping (281 ± 176/239 ± 166 sites/patient) was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (n = 32) or redo‐AF ablation (n = 10). All electrogram recordings were visually reviewed and artifactual signals were excluded leaving a total of 21 846 for analysis. Electrogram characteristics evaluated were cycle length (CL), amplitude, Shannon's entropy (ShEn), fractionation interval, dominant frequency, organizational index, and cycle length of most recurrent morphology (CLR) from morphology recurrence plot analysis. Results: Electrogram characteristics were correlated to each other. All pairwise comparisons were significant (p <.001) except for dominant frequency and CLR (p =.59), and amplitude and dominant frequency (p =.38). Only ShEn and fractionation interval demonstrated a strong negative correlation (r = −.94). All other pairwise comparisons were poor to moderately correlated. The relationships are highly conserved among patients, in the RA versus LA, and in those undergoing initial versus redo ablations. Antiarrhythmic drug therapy did not have a significant effect on electrogram characteristics, except minimum ShEn. Electrogram characteristics associated with ablation outcome were shorter minimum CLR, lower minimum ShEn, and longer mimimum CL. There was minimal overlap between the top 10 sites identified by one electrogram characteristic and the top 10 sites identified by the other 10 characteristics. Conclusion: Multiple techniques can be employed for electrogram analysis in AF. In this analysis of eight different electrogram characteristics, seven were poorly to moderately correlated and do not identify similar locations. Only some characteristics were predictive of ablation outcome. Further studies to consider electrogram properties, perhaps in combination, for categorizing and/or mapping AF are warranted. [ABSTRACT FROM AUTHOR]

The author discusses a study by F. Bahlke and colleagues which report procedural and clinical outcomes of 50 patients undergoing catheter ablation of persistent atrial fibrillation (AF), supported by the Volta VX1 software. Topics include majority of the patients included in the study, how catheter ablation was performed, and aspects that should be considered when interpreting the data presented by Bahlke and colleagues.

Introduction: A quantifiable, automated standard of analyzing heart rhythm has long eluded cardiologists due, in part, to the limitations in technology and the ability to analyze large electrogram datasets. In this proof‐of‐concept study, we propose new measures to quantify plane activity in atrial fibrillation (AF) using our Representation of Electrical Tracking of Origin (RETRO)‐Mapping software. Methods: We recorded 30 s segments of electrograms at the lower posterior wall of the left atrium using a 20‐pole double loop catheter (AFocusII). The data were analyzed with the custom RETRO‐Mapping algorithm in MATLAB. Thirty second segments were analyzed for number of activation edges, conduction velocity (CV), cycle length (CL), activation edge direction, and wavefront direction. These features were compared across 34 613 plane edges in three types of AF: persistent AF treated with amiodarone (11 906 wavefronts), persistent AF without amiodarone (14 959 wavefronts), and paroxysmal AF (7748 wavefronts). Change in activation edge direction between subsequent frames and change in overall wavefront direction between subsequent wavefronts were analyzed. Results: All activation edge directions were represented across the lower posterior wall. The median change in activation edge direction followed a linear pattern for all three types of AF with R2 = 0.932 for persistent AF treated without amiodarone, R2 = 0.942 for paroxysmal AF, and R2 = 0.958 for persistent AF treated with amiodarone. All medians and the standard deviation error bars remained below 45° (suggesting all activation edges were traveling within a 90° sector, a criterion for plane activity). The directions of approximately half of all wavefronts (56.1% for persistent without amiodarone, 51.8% for paroxysmal, 48.8% for persistent with amiodarone) were predictive of the directions of the subsequent wavefront. Conclusion: RETRO‐Mapping can measure electrophysiological features of activation activity and this proof‐of‐concept study suggests that this can be extended to the detection of plane activity in three types of AF. Wavefront direction may have a role in future work for predicting plane activity. For this study, we focused more on the ability of the algorithm to detect plane activity and less the differences between the types of AF. Future work should be in validating these results with a larger data set and comparing with other types of activation such as rotational, collision, and focal. Ultimately, this work can be implemented in real‐time for prediction of wavefronts during ablation procedures. [ABSTRACT FROM AUTHOR]

Introduction: Scar‐related ventricular tachycardia (VT) usually results from an underlying reentrant circuit facilitated by anatomical and functional barriers. The later are sensitive to the direction of ventricular activation wavefronts. We aim to evaluate the impact of different ventricular activation wavefronts on the functional electrophysiological properties of myocardial tissue. Methods: Patients with ischemic heart disease referred for VT ablation underwent high‐density mapping using Carto®3 (Biosense Webster). Maps were generated during sinus rhythm, right and left ventricular pacing, and analyzed using a new late potential map software, which allows to assess local conduction velocities and facilitates the delineation of intra‐scar conduction corridors (ISCC); and for all stable VTs. Results: In 16 patients, 31 high‐resolution substrate maps from different ventricular activation wavefronts and 7 VT activation maps were obtained. Local abnormal ventricular activities (LAVAs) were found in VT isthmus, but also in noncritical areas. The VT isthmus was localized in areas of LAVAs overlapping surface between the different activation wavefronts. The deceleration zone location differed depending on activation wavefronts. Sixty‐six percent of ISCCs were similarly identified in all activating wavefronts, but the one acting as VT isthmus was simultaneously identified in all activation wavefronts in all cases. Conclusion: Functional based substrate mapping may improve the specificity to localize the most arrhythmogenic regions within the scar, making the use of different activation wavefronts unnecessary in most cases. [ABSTRACT FROM AUTHOR]

Introduction: Ablation of atrial fibrillation (AF) is usually not considered in patients with rheumatic mitral stenosis (RMS). We analyzed the results of a combined procedure of AF ablation and percutaneous balloon mitral commissurotomy (PBMC). Methods: We prospectively included 22 patients with severe RMS to undergo a combined PBMC + AF ablation procedure. Noninvasive mapping of the atria was also performed. A historical sample of propensity‐scored matched patients who underwent PBMC alone was used as controls. The primary endpoint was freedom from AF/AT at 1‐year. Multivariate analysis evaluated sinus rhythm (SR) predictors. Results: Successful pulmonary vein isolation and electrocardiographic imaging‐based drivers ablation was performed in 20 patients following PBMC. At 1‐year, 75% of the patients in the combined group were in SR compared to 40% in the propensity‐score matched group (p = 0.004). The composite of AF recurrence, need for mitral surgery and all‐cause mortality was also more frequent in the control group (65% vs. 30%; p = 0.005). Catheter ablation (odds ratio [OR] 1.58; 95% confidence interval [CI] [1.17–17.37]; p = 0.04) and AF type (OR 1.46; 95% CI [1.05–82.64]; p < 0.001) were the only independent predictors of SR at 1‐year. Noninvasive mapping in the combined group showed that the number of simultaneous rotors (OR 2.10; 95% CI [1.41–10.2]; p = 0.04) was the only independent predictor of AF. Conclusion: A combined procedure of AF ablation and PBMC significantly increased the proportion of patients in sinus rhythm at 1‐year. Noninvasive mapping may help to improve AF characterization and guide personalized AF treatment. [ABSTRACT FROM AUTHOR]

Introduction: Multiple groups have reported on the usefulness of ablating in atrial regions exhibiting abnormal electrograms during atrial fibrillation (AF). Still, previous studies have suggested that ablation outcomes are highly operator‐ and center‐dependent. This study sought to evaluate a novel machine learning software algorithm named VX1 (Volta Medical), trained to adjudicate multipolar electrogram dispersion. Methods: This study was a prospective, multicentric, nonrandomized study conducted to assess the feasibility of generating VX1 dispersion maps. In 85 patients, 8 centers, and 17 operators, we compared the acute and long‐term outcomes after ablation in regions exhibiting dispersion between primary and satellite centers. We also compared outcomes to a control group in which dispersion‐guided ablation was performed visually by trained operators. Results: The study population included 29% of long‐standing persistent AF. AF termination occurred in 92% and 83% of the patients in primary and satellite centers, respectively, p = 0.31. The average rate of freedom from documented AF, with or without antiarrhythmic drugs (AADs), was 86% after a single procedure, and 89% after an average of 1.3 procedures per patient (p = 0.4). The rate of freedom from any documented atrial arrhythmia, with or without AADs, was 54% and 73% after a single or an average of 1.3 procedures per patient, respectively (p < 0.001). No statistically significant differences between outcomes of the primary versus satellite centers were observed for one (p = 0.8) or multiple procedures (p = 0.4), or between outcomes of the entire study population versus the control group (p > 0.2). Interestingly, intraprocedural AF termination and type of recurrent arrhythmia (i.e., AF vs. AT) appear to be predictors of the subsequent clinical course. Conclusion: VX1, an expertise‐based artificial intelligence software solution, allowed for robust center‐to‐center standardization of acute and long‐term ablation outcomes after electrogram‐based ablation. [ABSTRACT FROM AUTHOR]

Introduction: Markers predicting atrial fibrillation (AF) termination and freedom from AF/atrial tachycardia (AT) has been proposed. This study aimed to evaluate the role of novel coronary sinus (CS) electrogram characteristics in predicting the acute ablation response and freedom from AF/AT during follow‐up. Methods: Patients undergoing ablation for persistent AF as part of the Stochastic Trajectory Analysis of Ranked signals mapping study were included. Novel CS electrogram characteristics including CS cycle length variability (CLV) and CS activation pattern stability (APS) and proportion of low voltage zones (LVZs) were reviewed as potential predictors for AF termination on ablation and freedom from AF/AT during follow‐up. The relationship between localized driver characteristics and CS electrogram characteristics was also assessed. Results: Sixty‐five patients were included. AF termination was achieved in 51 patients and 80% of patients were free from AF/AT during a follow‐up of 29.5 ± 3.7 months. CS CLV of <30 ms, CS APS of ≥30% and proportion of LVZ < 30% showed high diagnostic accuracy in predicting AF termination on ablation and freedom from AF/AT during follow‐up (CS CLV odds ratio [OR] 25.6, area under the curve [AUC] 0.91; CS APS OR 15.9, AUC 0.94; proportion of LVZs OR 21.4, AUC 0.88). These markers were independent predictors of AF termination on ablation and AF/AT recurrence during follow‐up. Ablation of a smaller number of drivers that demonstrate greater dominance strongly correlate with greater CS organization. Conclusion: Novel CS electrogram characteristics were independent predictors of AF termination and AF/AT recurrence during follow‐up. These markers can potentially aid in predicting outcomes and guide ablation and follow‐up strategies. [ABSTRACT FROM AUTHOR]

Background: Infection remains a major complication of cardiac implantable electronic devices and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter‐defibrillator (S‐ICD), can reduce the risk of serious infection‐related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S‐ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S‐ICD infections. Therefore, an expert panel was convened to develop a consensus on these topics. Methods: An expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S‐ICD infections. Two face‐to‐face meetings of high‐volume S‐ICD implanters and an infectious diseases specialist, with expertise in cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre‐, peri‐, and postimplant to reduce S‐ICD infection risk. Results: Expert panel consensus on recommended steps for patient preparation, S‐ICD implantation, and postoperative management was developed to provide guidance in individual patient management. Conclusion: Achieving expert panel consensus by process mapping methodology for S‐ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S‐ICD infection. [ABSTRACT FROM AUTHOR]

Background: Automated systems for substrate mapping in the context of ventricular tachycardia (VT) ablation may annotate far‐field rather than near‐field signals, rendering the resulting maps hard to interpret. Additionally, quantitative assessment of local conduction velocity (LCV) remains an unmet need in clinical practice. We evaluate whether a new late potential map (LPM) algorithm can provide an automatic and reliable annotation and localized bipolar voltage measurement of ventricular electrograms (EGMs) and if LCV analysis allows recognizing intrascar conduction corridors acting as VT isthmuses. Methods: In 16 patients referred for scar‐related VT ablation, 8 VT activation maps and 29 high‐resolution substrate maps from different activation wavefronts were obtained. In offline analysis, the LPM algorithm was compared to manually annotated substrate maps. Locations of the VT isthmuses were compared with the corresponding substrate maps in regard to LCV. Results: The LPM algorithm had an overall/local abnormal ventricular activity (LAVA) annotation accuracy of 94.5%/81.1%, which compares to 83.7%/23.9% for the previous wavefront algorithm. The resultant maps presented a spatial concordance of 88.1% in delineating regions displaying LAVA. LAVA median localized bipolar voltage was 0.22 mV, but voltage amplitude assessment had modest accuracy in distinguishing LAVA from other abnormal EGMs (area under the curve: 0.676; p <.001). LCV analysis in high‐density substrate maps identified a median of two intrascar conduction corridors per patient (interquartile range: 2–3), including the one acting as VT isthmus in all cases. Conclusion: The new LPM algorithm and LCV analysis may enhance substrate characterization in scar‐related VT. [ABSTRACT FROM AUTHOR]

The article focuses on the atrial fibrillation (AF) mapping technology called RETRO-Mapping, it analyzes activation patterns during AF using a multipolar catheter. It reports that the wavefront activation directions and demonstrates that activation patterns can predict subsequent wavefront patterns, providing insights into the complexities of AF activation patterns and potentially improving treatment approaches.

Background: A novel 3D mapping system (KODEX‐EPD, EPD Solutions) enables catheter localization and real‐time 3D cardiac mapping. Objective: To evaluate left atrium (LA) anatomical mapping accuracy created by the KODEX‐EPD system during pulmonary vein isolation (PVI) compared with gold standard computed tomography (CT) images acquired from the same patients before the procedure. Methods: In 15 consecutive patients who underwent PVI, 3D mapping of the LA was created on the KODEX‐EPD system using the Achieve catheter. Pulmonary vein (PV), posterior wall, and appendage anatomy and diameters, were compared to the CT 3D reconstruction measured on the CARTO 3 system. Measurements were done independently by two physicians in each method. Linear correlation and agreement between CT and EPD measurements were assessed by Spearman correlation and Bland‐Altman plot. Results: Mean LA mapping time was 7.7 ± 3.6 min. Very high interobserver correlation was found for both EPD and CT measurements (Spearman r =.9). High correlation (r =.75) was found between CT and EPD measurements. Bland‐Altman plot method revealed that measurements assessed by EPD were slightly higher than those assessed by CT. Mean difference was 3.5 mm, p <.01. In 2 (13.5%) patients each, disagreement regarding the presence of a left common PV and a right middle accessory vein anatomy was seen. Conclusion: The new KODEX‐EPD mapping system allows quick and accurate mapping of the LA with high correlation to CT imaging. Some differences in left common and accessory right middle vein anatomy were seen. [ABSTRACT FROM AUTHOR]

Background: Left bundle branch pacing (LBBP) is a new near‐physiological pacing modality. Distinguishing left ventricular septal only pacing (LVSP) from nonselective LBBP still needs clarification. This prospective study sought to establish a differentiation algorithm to confirm LBBP. Methods and Results: LBBP was attempted in consecutive patients. If direct LBB capture (LBBP) could not be confirmed, LVSP was considered to have been achieved. Intracardiac left ventricular (LV) activation sequence and activation time were analyzed using coronary sinus (CS) electrogram mapping. Electrophysiological parameters including S‐CSmax, S‐CSmin, LV lateral wall activation time, ΔLV, and LBB potential were compared between LBBP and LVSP. Stimulated LV activation time (S‐LVAT) and stimulated QRS duration (S‐QRSd) were also compared between the two groups. Multivariate logistic regression analysis was used to develop a prediction algorithm for LBBP. Of the 43 prospectively enrolled patients, 27 underwent LBBP and 16 underwent LVSP. All LBBP patients showed identical LV activation sequences to their intrinsic rhythm while no LVSP patients maintained their intrinsic sequence. S‐CSmax, ΔLV, LV lateral wall activation time, and S‐LVAT during LBBP were significantly shorter than those during LVSP. Combining LBB potential with S‐LVAT had the largest area under the curve (AUC) of 0.985 for confirming LBBP with a sensitivity of 95.2% and a specificity of 93.7%. Conclusions: Compared with LVSP, LBBP preserves a normal LV activation sequence and better electrical synchrony. A combination of LBB potential with S‐LVAT can be an effective and practical model to distinguish LBBP from LVSP during implantation in patients with normal LBB activation. [ABSTRACT FROM AUTHOR]

Introduction: Microstructural abnormalities at the epicardium of the right ventricular outflow tract (RVOT) may provide the arrhythmia substrate in Brugada syndrome (BrS). Endocardial unipolar electroanatomical mapping allows the identification of epicardial abnormalities. We evaluated the clinical implications of an abnormal endocardial substrate as perceived by high‐density electroanatomical mapping (HDEAM) in patients with BrS. Methods: Fourteen high‐risk BrS patients with aborted sudden cardiac death (SCD) (12 males, mean age: 41.9 ± 11.8 years) underwent combined endocardial‐epicardial HDEAM of the right ventricle/RVOT, while 40 asymptomatic patients (33 males, mean age: 42 ± 10.7 years) underwent endocardial HDEAM. Based on combined endocardial‐epicardial procedures, endocardial HDEAM was considered abnormal in the presence of low voltage areas (LVAs) more than 1 cm2 with bipolar signals less than 1 mV and unipolar signals less than 5.3 mV. Programmed ventricular stimulation (PVS) was performed in all patients. Results: The endocardial unipolar LVAs were colocalized with epicardial bipolar LVAs (p =.0027). Patients with aborted SCD exhibited significantly wider endocardial unipolar (p <.01) and bipolar LVAs (p <.01) compared with asymptomatic individuals. A substrate size of unipolar LVAs more than 14.5 cm2 (area under the curve [AUC]: 0.92, p <.001] and bipolar LVAs more than 3.68 cm2 (AUC: 0.82, p =.001) distinguished symptomatic from asymptomatic patients. Patients with ventricular fibrillation inducibility (23/54) demonstrated broader endocardial unipolar (p <.001) and bipolar LVAs (p <.001) than noninducible patients. The presence of unipolar LVAs more than 13.5 cm2 (AUC: 0.95, p <.001) and bipolar LVAs more than 2.97 cm2 (AUC: 0.78, p <.001) predicted a positive PVS. Conclusion: Extensive endocardial electroanatomical abnormalities identify high‐risk patients with BrS. Endocardial HDEAM may allow risk stratification of asymptomatic patients referred for PVS. [ABSTRACT FROM AUTHOR]

Introduction: Some patients have late recurrence after acutely successful radiofrequency catheter ablation (RFCA) of premature ventricular complexes (PVCs). The aim of this study was to evaluate predictors of long‐term success following acutely successful PVC RFCA. Methods: We identified consecutive patients at our institution with frequent PVCs undergoing RFCA and reviewed procedural data and medical records. Acute success was defined as elimination of targeted PVCs for at least 30‐min after RFCA. Long‐term success was defined as absence of targeted PVCs during all follow‐up visits and PVC‐burden <5% on follow‐up monitoring. Results: Among 241 patients (mean age 57 ± 15 years, 58% male), 161 (66.8%) had long‐term success with median follow‐up of 17.7 (IQR, 12.2–29.8) months. Unadjusted predictors of late PVC recurrence were increasing age, diabetes mellitus and alcohol use, while female‐sex, shorter ablation‐time, right ventricular PVC‐origin, single PVC morphology, and earliest bipolar activation ≥24 ms pre‐QRS were predictors of long‐term success. In multivariate‐analysis, female‐sex, single‐PVC morphology and earliest‐onset of PVC ≥ 24 ms pre‐QRS were independent predictors for long‐term success. The positive‐predictive value of earliest‐bipolar onset of PVC ≥ 24 ms pre‐QRS for long‐term success was 0.77 (p <.001). Negative‐predictive value of PVC < 15 ms pre‐QRS for long‐term success was 0.86 (p =.003), suggesting that RFCA when the bipolar electrogram preceded QRS by <15 ms was unlikely to result in long‐term success. Conclusions: Female‐sex, single‐PVC morphology, and earliest‐onset of bipolar electrogram ≥24 ms pre‐QRS were multivariable predictors of long‐term success in patients with PVCs undergoing RFCA. RFCA at sites with local onset <15 ms pre‐QRS are unlikely to be successful. [ABSTRACT FROM AUTHOR]

Background: Low voltage areas (LVAs) are most commonly observed on the left atrial (LA) septal/anterior wall. Objective: We explored the mechanisms of LA septal/anterior wall reentrant tachycardias (LASARTs) using ultrahigh resolution mapping. Methods: This study included seven consecutive LASARTs in six patients (75 [62.2–82.8] years, 4 women) who underwent atrial tachycardia (AT) mapping and ablation using Rhythmia systems. Results: The AT cycle length was 266 (239–321) ms. During ATs, 11.0 (9.0–12.9) cm2 of LVAs were identified in all, and 0.8 (0.7–1.7) cm2 of dense scar was identified in four patients. Five ATs rotated around dense scar, while two rotated around functional linear block, which was confirmed during atrial pacing after AT termination. The AT circuit length was 8.7 ± 2.1 cm with a conduction velocity of 30.4 ± 3.7 cm/s. A median of 3.0 (2.0–4.0) slow conduction areas per circuit were identified, and 17/23 (73.9%) areas were present in LVAs, while they were at the border of the LVA and normal voltage areas in the remaining 6/23 (26.1%). Global activation histograms facilitated the identification of the critical isthmus in all. Tailor‐made ablation at critical isthmuses successfully eliminated all ATs. However, one patient with AT related to functional linear block experienced recurrent AT related to dense scar, which progressed after the procedure. During a mean 14 ± 13 month follow‐up after the last procedure, no patients experienced recurrent ATs without any complications. Conclusion: LASARTs consist of not only fixed conduction blocks but also functional conduction blocks. Ultrahigh resolution mapping is highly useful to decide the optimal tailor‐made ablation strategy based on the mechanisms. [ABSTRACT FROM AUTHOR]

Introduction: Advancing age is a known risk factor for developing atrial fibrillation (AF), yet it is unknown which electrophysiological changes contribute to this increased susceptibility. The goal of this study is to investigate conduction disturbances and unipolar voltages (UV) related to aging. Methods: We included 216 patients (182 male, age: 36–83 years) without a history of AF undergoing elective coronary artery bypass surgery. Five seconds of sinus rhythm were recorded intraoperatively at the right atrium (RA), Bachmann's bundle (BB), the left atrium and the pulmonary vein area (PVA). Conduction delay (CD), ‐block (CB), ‐velocity (CV), length of longest CB lines and UV were assessed in all regions. Results: With aging, increasing conduction disturbances were found, particularly at RA and BB (RA: longest CB line rs =.158, p =.021; BB: CB prevalence rs =.206, p =.003; CV rs = −.239, p <.0005). Prevalence of low UV areas (UV <5th percentile) increased with aging at the BB and PVA (BB: rs =.237, p <.0005 and PVA: rs =.228, p =.001). Conclusions: Aging is accompanied by an increase in conduction disturbances during sinus rhythm and a higher prevalence of low UV areas, particularly at BB and in the RA. These electrophysiological alterations could in part explain the increasing susceptibility to AF development associated with aging. [ABSTRACT FROM AUTHOR]

The standard technique for accessory pathway ablation involves mapping along the mitral and tricuspid annulus to localize the regions of earliest ventricular activation during antegrade pathway conduction, earliest atrial activation during retrograde conduction or detection of an accessory pathway potential. In some cases despite what appears to be appropriate mapping, catheter positioning and adequate power delivery the ablation is not successful. In many of these cases, the pathway is felt to be inaccessible because of a location remote from the mitral or tricuspid annulus that cannot be affected by endocardial power delivery along the annulus. In the case of difficult left sided pathways, some may be reached and ablated via the coronary sinus or its branches. Right sided pathways cannot be approached in this fashion since there is no venous structure analogous to the coronary sinus around the tricuspid annulus. Alternative mapping and ablation techniques for these difficult pathways have included epicardial mapping via direct pericardial access or attempts to localize pathway insertion areas remote from the valve annulus which may be amenable to endocardial ablation. We describe the use of post‐pacing interval mapping to localize the atrial input of a right sided antegrade only accessory pathway that was resistant to conventional mapping and ablation strategies. [ABSTRACT FROM AUTHOR]

Introduction: Substrate‐based catheter ablation approaches to ventricular tachycardia (VT) focus on low‐voltage areas and abnormal electrograms. However, specific electrogram characteristics in sinus rhythm are not clearly defined and can be subject to variable interpretation. We analyzed the potential ablation target size using automatic abnormal electrogram detection and studied findings during substrate mapping in the VT isthmus area. Methods and Results: Electrogram characteristics in 61 patients undergoing scar‐related VT ablation using ultrahigh‐density 3D‐mapping with a 64‐electrode mini‐basket catheter were analyzed retrospectively. Forty‐four complete substrate maps with a mean number of 10319 ± 889 points were acquired. Fractionated potentials detected by automated annotation and manual review were present in 43 ± 21% of the entire low‐voltage area (<1.0 mV), highly fractionated potentials in 7 ± 8%, late potentials in 13 ± 15%, fractionated late potentials in 7 ± 9% and isolated late potentials in 2 ± 4%, respectively. Highly fractionated potentials (>10 ± 1 fractionations) were found in all isthmus areas of identified VT during substrate mapping, while isolated late potentials were distant from the critical isthmus area in 29%. Conclusion: The ablation target area varies enormously in size, depending on the definition of abnormal electrograms. Clear linking of abnormal electrograms with critical VT isthmus areas during substrate mapping remains difficult due to a lack of specificity rather than sensitivity. However, highly fractionated, low‐voltage electrograms were found to be present in all critical VT isthmus sites. [ABSTRACT FROM AUTHOR]

Introduction: The optimal ablation approach for persistent atrial fibrillation (AF) remains unclear. Methods and Results: Objective was to compare the long‐term rates of freedom from AF/AT in patients that underwent STAR mapping guided ablation against outcomes of patients undergoing conventional ablation procedures. Patients undergoing ablation for persistent AF as part of the Stochastic Trajectory Analysis of Ranked signals (STAR) mapping study were included. Outcomes following 'pulmonary vein isolation (PVI) plus STAR mapping guided ablation (STAR mapping cohort) were compared to patients undergoing PVI alone ablation during the same time period and also a propensity‐matched cohort undergoing PVI plus the addition of complex fractionated electrogram (CFAE) and/or linear ablation ("conventional ablation"). Rates of procedural AF termination and freedom from AF/AT during follow‐up were compared. Sixty‐five patients were included in both the STAR cohort and propensity matched conventional ablation cohort. AF termination rates were significantly higher in the STAR cohort (51/65, 78.5%) than conventional ablation cohort (10/65, 15.4%) and PVI alone ablation cohort (13/50, 26.0%; STAR cohort vs. other 2 cohorts both p <.001). There was no significant difference in procedure time between the three cohorts. During ≥20 months follow‐up a lower proportion of patients had AF/AT recurrence in the STAR cohort (20.0%) compared with the conventional ablation cohort (50.8%) or the PVI alone ablation cohort (50.0%; both p <.05 compared to STAR cohort). Conclusions: Outcomes of PVI plus STAR mapping guided ablation was superior to PVI alone or in combination with linear/CFAE ablation. A multicenter randomized controlled trial is planned to confirm these findings. [ABSTRACT FROM AUTHOR]

Rhythm control of persistent atrial fibrillation (AF) patients represents a challenge for the modern interventional cardiac electrophysiologist; as a matter of fact, there is still divergence regarding the best ablative approach to adopt in this population. Different investigational endpoints, variability of techniques and tools, significant technological evolution, and the lack of universally accepted pathophysiological models engendered a considerable heterogeneity in terms of techniques and outcomes, so much that the treatment of persistent subtypes of AF commonly still relies mainly on pulmonary vein (PV) isolation. The purpose of the present review is to report the current experimental and clinical evidence supporting the importance of mapping and ablating non‐PV triggers and describe our institutional approach for the ablation of nonparoxysmal AF. [ABSTRACT FROM AUTHOR]

Introduction: An electrical superior vena cava (SVC) isolation from the right atrium (RA) sometimes can be challenging. For a safe and efficient SVC isolation, we aimed to visualize the accurate position of the SVC‐RA junction on a three‐dimensional (3D) mapping system using the decremental conduction properties of the SVC‐RA junction in patients with atrial fibrillation (AF). Methods: This study consisted of 15 consecutive AF patients (11 males, age 59 ± 10 years). A 3D mapping catheter was positioned in the SVC‐RA junction region while delivering a single extra‐stimulus from the right atrial appendage (RAA), to discriminate the RA and SVC potentials. The electrophysiological SVC‐RA junction was defined as the most proximal points where the SVC potentials were recorded, which were tagged on the 3D mapping system around the SVC‐RA junction, where radiofrequency energy applications were applied. Results: Around the SVC‐RA junction, 9 ± 2 points were tagged on the 3D mapping system. The highest and lowest SVC‐RA junction points were located on the anterior wall and posterior wall, respectively. The difference in the level between the highest and lowest SVC‐RA junction points was 16.2 ± 6.3 mm. A successful SVC isolation was obtained in all patients without any complications. Conclusion: The plane of the electrophysiologically defined SVC‐RA junction was not perpendicular to the body axis, but slanted due to the anterior side being higher. Recognizing the precise location of the SVC‐RA junction would contribute to a safe and efficacious SVC isolation. [ABSTRACT FROM AUTHOR]

Catheter ablation is commonly used for treatment of persistent atrial fibrillation (AF). Pulmonary vein isolation (PVI) is still the cornerstone for the procedure, however, outcomes are consistently lower compared to paroxysmal AF. It is hypothesized that it could be due to lack of durable lesions or the presence of non‐PV targets that remain after PVI. Numerous advances in ablation catheter technologies and mapping systems may potentially achieve lower recurrence rates in the future. Ongoing research is required to discover the best technique for persistent AF ablation. The purpose of this review is to describe the new, developing technologies that may improve the outcome of this procedure in the persistent AF population. [ABSTRACT FROM AUTHOR]

The article discusses the study "Identification of Critical Isthmus Using Coherent Mapping in Patients With Scar-Related Atrial Tachycardia," by J. J. B. Vicera, Y. Lin, P. Lee and colleagues, that was published in this issue of the publication. Topics covered include complex atrial tachycardia, coherent versus standard local activation time mapping, and the interpretation and optimization of the coherent-mapping module.

Introduction: Isolation of the left atrial appendage (LAA) is often performed in persistent atrial fibrillation (AF). Propagation patterns in the LAA during AF remain to be elucidated. We sought to characterize propagation patterns in the LAA during AF in persistent AF. Methods: Persistent AF patients undergoing catheter ablation were studied. Pulmonary vein isolation (PVI) was performed during continuous AF. If AF was not terminated by PVI, bi‐atrial mapping was performed using a multi‐electrode catheter during AF. Maps were collected at each site for 30 seconds and analyzed offline with a novel software, CARTOFINDER. This software made automatic determinations of whether activation was focal or rotational. The left atrium (LA) was divided into five regions, of which the LAA was one, and the right atrium (RA) into three. Results: Eighty patients were studied (62 ± 10 years, 65 males). On average, 9.6 ± 2.2 and 4.1 ± 1.2 maps were created in the LA and RA, respectively. The LAA was mapped in 70 patients, resulting in 85 maps. In the LAA, activation was identified as focal more often than rotational (64 [91%] vs 10 [14%] patients, P <.001), seven patients displayed both. The number of focal activation events was greatest in the LAA (28.5 events/30 seconds [interquartile range, 15‐54]) of the eight atrial regions. During focal activation, sites designated as earliest activation frequently covered a wide area, rather than being localized to a discrete site (5.4 ± 3.1 electrodes). Conclusions: The results of this study suggest that focal activation is a major mechanism underlying the arrhythmogenicity of the LAA in persistent AF. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role of driver mechanism and the effect of electrogram dispersion–guided driver mapping and ablation in atrial fibrillation (AF) at different stages of progression. Methods: A total of 256 consecutive patients with AF who had undergone pulmonary vein isolation (PVI) plus driver ablation or conventional ablation were divided into three groups: paroxysmal atrial fibrillation (PAF; group A, n = 51); persistent atrial fibrillation (PsAF; group B, n = 38); and long standing–persistent atrial fibrillation (LS‐PsAF; group C, n = 39). PVI was performed with the guidance of the ablation index. The electrogram dispersion was analyzed for driver mapping. Results: The most prominent driver regions were at roof (28.0%), posterior wall (17.6%), and bottom (21.3%). From patients with PAF to those with PsAF and LS‐PsAF: the complexity of extra‐pulmonary vein (PV) drivers including distribution, mean number, and area of dispersion region increased (P <.001). Patients who underwent driver ablation vs conventional ablation had higher procedural AF termination rate (76.6% vs 28.1%; P <.001). With AF progression, the termination rate gradually decreased from group A to group C, and the role of PVI in AF termination was also gradually weakened from group A to group C (39.6%, 7.4%, and 4.3%; P <.001) in patients with driver ablation. At the end of the follow‐up, the rate of sinus rhythm maintenance was higher in patients with driver ablation than those with conventional ablation (89.1% vs 70.3%; P <.001). Conclusion: The formation of extra‐PV drivers provides an important mechanism for AF maintenance with their complexity increasing with AF progression. Electrogram dispersion–guided driver ablation appears to be an efficient adjunctive approach to PVI for AF treatment. [ABSTRACT FROM AUTHOR]

Introduction: The optimal way to map localized drivers in persistent atrial fibrillation (AF) remains unclear. The objective of the study was to apply a novel vector mapping approach called Stochastic Trajectory Analysis of Ranked signals (STAR) in AF. Methods and Results: Patients having persistent AF ablation were included. Early sites of activation (ESA) identified on global STAR maps created with basket catheters were used to guide AF ablation post‐pulmonary vein isolation (PVI). All patients also had sequential STAR maps created with ≥10 PentaRay recordings of 30 seconds. These were validated offline in their ability to identify the ESA targeted with a study‐defined ablation response (AF termination or cycle length [CL] slowing of ≥30 ms). Thirty‐two patients were included in whom 92 ESA were identified on the global STAR maps, with 73 of 83 targeted sites demonstrating an ablation response (24 AF termination and 49 CL slowing). Sixty‐one out of 73 (83.6%) ESA were also identified on the sequential STAR maps. These showed greater consistency (P < .001), were seen pre‐ and post‐PVI (P < .001) and were more likely to be associated with AF termination on ablation (P = .007). The sensitivity and specificity of sequential mapping for the detection of ESA with an ablation response was 84.9% (95% confidence interval [CI] = 74.6‐92.2) and 90.0% (95% CI = 55.5‐99.8), respectively. During a follow‐up of 19.4 ± 3.7 months, 28 (80%) patients were free from AF/atrial tachycardia. Conclusions: STAR mapping consistently identified ESA in all patients and the ablation response was compatible with ESA being driver sites. Mechanistically important ESA were successfully identified using sequential recordings. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 70‐year‐old male patient with a history of a large anterior wall myocardial infarction presented to institute with recurrent episodes of ventricular tachycardia (VT) terminated by antitachycardia pacing from his implantable cardioverter‐ defibrillator. The article discusses that his left ventricular (LV) ejection fraction was 35%. VT mapping and ablation was undertaken using the Rhythmia mapping system (Boston Scientific).

An editorial is presented on the re‐interpreting complex atrial tachycardia maps using global atrial vectors. The article discusses that the mapping and ablation of atrial tachycardias (AT) can be challenging, particularly in patients with prior ablation or structural atrial disease; and activation mapping is thus often used in parallel. In recent years, high‐ resolution catheters have increasingly been used to reveal micro‐reentry at sites that appeared focal.

Introduction: The critical question for technological advancement of catheter ablation of atrial fibrillation (AF) is whether a creative new concept can combine and even improve the options of single‐tip catheters with the simplicity of the use of balloon catheters. Herein are described the results from the first clinical study of a new multielectrode contact‐mapping plus ablation array (Globe) offering such a complete solution. Methods and Results: The multielectrode Globe array consists of 16 flat ribs with 122 gold‐plated electrodes. Each electrode can record electrograms, ablate, pace, and can measure tissue contact and temperature. Single‐shot pulmonary vein isolation (PVI) is possible with temperature‐guided ablation of up to 24 electrodes simultaneously with automatic, individual power control of every electrode. Sixty patients with symptomatic AF underwent PVI using the Globe. In all sixty patients, acute PVI was achieved in 232 of 234 attempted PVs (99.1%). In 34 patients treated with "single‐hot‐shot" ablation, PVI was achieved in 136 of 136 PVs (100%). Single‐procedure 12‐month freedom from AF off antiarrhythmic drugs in the "single‐hot‐shot" group was 75.5% and freedom from AF/atrial tachycardia 72.3%. In two patients, pericardial tamponade was observed, one after a transseptal puncture, and one during array insertion with an over‐advanced sheath. There were no other device‐related serious adverse events, including stroke, PV stenosis, esophageal perforation, or phrenic nerve palsy. Conclusions: In this first clinical series, the Globe catheter was found to be an easy‐to‐use system for single‐shot PVI. The continuously updated multielectrode voltage and activation mapping data indicate future options for mapping and ablation beyond PVI. [ABSTRACT FROM AUTHOR]

Background: Conventional mapping techniques during atrial fibrillation (AF) are difficult to apply because of cycle length irregularity. Mapping studies are usually restricted to short durations of AF in limited regions because of the laborious manual annotation of local activation time (LAT). The purpose of this study was to test an automated algorithm to map activation during AF, with comparable accuracy to manual annotation. Methods: Left atrial (LA) mapping was performed using a 20‐pole double loop catheter (AFocusII) in 30‐second data segments from 16 patients. The new algorithm (RETRO‐Mapping) was designed to detect wavefront propagation between electrodes, and display activating wavefronts on a two‐dimensional representation of the catheter. Activation patterns were validated against their bipolar electrograms and with isochronal maps. The mapping protocol was approved by the research ethics committee (13/LO1169 and 14/LO1367). Results: During AF, uniform wavefront activation direction (mean ± SD, degrees) from manually constructed isochronal maps was comparable to RETRO‐Propagation Map (RETRO‐PM) and RETRO‐Automated Direction (RETRO‐AD): 1 ± 6.9 for RETRO‐PM; and 2 ± 6.6 for RETRO‐AD. There was no significant difference in activation direction assigned to 1373 uniform wavefronts during AF when comparing RETRO‐PM with RETRO‐AD (Bland‐Altman mean difference: −0.1 degrees; limits of agreement: −8.0 to 8.3; 95% CI −0.4 to 0.2; (r = 0.01) R2 = < 0.005; P = .77). Conclusion: We have developed and validated a new technique to map activation during AF. This technique shows comparable accuracy to that of conventional isochronal mapping with careful manual adjustment of LAT. [ABSTRACT FROM AUTHOR]

Introduction: Ablation of premature ventricular contractions (PVCs) has emerged as a safe and effective treatment in patients experiencing a high PVCs burden. Mapping of PVCs origin may sometimes be challenging. We sought to evaluate the accuracy of a new electrophysiological criterion, the distal‐to‐proximal (DP) delay, at localizing the optimal site for ablation of ventricular ectopic foci. Methods and Results: Consecutive patients with ablation attempts of symptomatic PVCs were included. Prematurity and DP delay—that is, the time duration between the onset of ablation catheter distal bipolar electrogram and the onset of proximal bipolar electrogram—were measured at successful and unsuccessful ablation sites by three blinded experienced electrophysiologists. Mean DP delay at effective ablation sites (N = 30) was significantly higher than at ineffective sites (N = 55) (23 ± 9 vs 11 ± 8 milliseconds; P < 0.0001). DP delay had good‐to‐excellent interrater reliability. A DP delay greater than or equal to 15 milliseconds had the highest accuracy at predicting a successful ablation site (sensitivity 0.97, the area under receiver operating characteristic curve 0.87; P < 0.0001). Conclusion: DP delay is an additional, simple, and effective electrophysiological parameter to accurately localize PVCs foci. [ABSTRACT FROM AUTHOR]

Introduction: Ventricular arrhythmias (VA) after left ventricular assist device (LVAD) placement are associated with increased morbidity and mortality. We sought to assess epicardial voltage characteristics at the time of LVAD implantation and investigate relationships between scar burden and postimplant VA. Methods and Results: Consecutive patients underwent open chest epicardial electroanatomic mapping immediately before LVAD implantation. Areas of low voltage and sites with local abnormal potentials were identified. Patients were followed prospectively for postimplant VA and clinical outcomes. Between 2015 and 2017, 36 patients underwent high‐density intraoperative epicardial voltage mapping; 15 had complete maps suitable for analysis. Mapping required a median of 11.8 (interquartile range [IQR], 8.5‐12.7) minutes, with a median of 2650 (IQR, 2139‐3191) points sampled per patient. Over a median follow‐up of 311 (IQR, 168‐469) postoperative days, four patients (27%) experienced sustained VA. Patients with postimplant VA were more likely to have had preimplant implantable cardioverter defibrillator shocks (100% vs 27%; P = 0.03), ventricular tachycardia storm (75% vs 9%; P = 0.03), and lower ejection fraction (13.5 vs 19.0%, P = 0.05). Patients with postimplant VA also had a significantly higher burden of epicardial low bipolar voltage points: 55.4% vs 24.9% of points were less than 0.5 mV (P = 0.01), and 88.9% vs 63.7% of points less than 1.5 mV (P = 0.004). Conclusions: Intraoperative high‐density epicardial mapping during LVAD implantation is safe and efficient, facilitating characterization of a potentially arrhythmogenic substrate. An increased burden of the epicardial scar may be associated with a higher incidence of postimplant VA. The role of empiric intraoperative epicardial ablation to mitigate risk of postimplant VA requires further study. [ABSTRACT FROM AUTHOR]

Background: The adjunctive approach is still unknown for atrial fibrillation (AF), which cannot be terminated after pulmonary vein isolation (PVI). We hypothesized that the driver ablation plus PVI was superior to PVI alone. Methods and Results: A total of 98 patients with paroxysmal AF were enrolled in this study and were divided into two groups, with one group undergoing PVI (n = 49) and the other group undergoing PVI + driver ablation (n = 49). The driver regions were defined as clusters of bipolar electrograms that displayed spatial dispersion spread over mean AF cycle length at a minimum of three adjacent bipolars of a PentaRay catheter. During the procedure, the most prominent driver regions before PVI were the roof (n = 27; 55.1%), PV antrum (n = 23; 46.9%), and the inferoposterior wall (n = 11; 22.4%). PVI can eliminate all drivers at PV antrum, but only terminate 30.4% of AF in the driver group. The AF termination rate in the driver ablation group was significantly higher than that in conventional ablation (93.9% vs 40.6%; P < 0.001). The rate of freedom from atrial tachyarrhythmia episodes by a single procedure at 6 months was significantly higher in the driver group than in the conventional group (91.6% vs 72.4%; P = 0.02). Conclusion: The present method is effective for AF driver identification. It guided ablation adjunctive to PVI increasing the rate of AF termination and improving the outcomes in patients with paroxysmal AF. [ABSTRACT FROM AUTHOR]

The article presents the discussion on first experience of using the novel three‐dimensional (3D) mapping system technology for atrial fibrillation (AF) ablation. Topics include operator using any mapping/ablation catheter to create the left atrium anatomy along with pulmonary veins' structure; and KODEX‐EPD imaging system properly creates high‐resolution images of cardiac anatomy by exploiting the distinct dielectric properties of biological tissue.

The article offers information on atrial fibrillation (AF) ablation by pulmonary vein isolation (PVI). Topics discussed include information on direct contact mapping of repetitive atrial activation patterns (RAAP); use of the Pentaray catheter which provides high resolution and stable electrode contact with atrial tissue; and information on validated mapping algorithms which help in the detection of more stable sources rather than transient sites.

Background: Automated algorithms may identify focal (FA) and rotational (RoA) activations during persistent atrial fibrillation (PeAF). Objective: To evaluate an automated algorithm for characterizing and assessing significance of FA/RoA. Methods: Eighty‐six PeAF ablation patients (1411 maps) were analyzed. Maps were obtained with a 64‐electrode basket using CARTOFINDER, which filters/annotates atrial unipolar electrograms over 30 seconds. Operators ablated FA/RoA followed by pulmonary vein isolation (PVI). The automated algorithm was retrospectively applied using QS patterns to identify FA and sequential activation gradients for RoA without phase mapping. Algorithm‐identified FA and RoA were validated against blinded adjudicators. Ablation of algorithm‐identified FA/RoA was related to procedural AF termination. Results: 73% ± 18% of electrodes (65% ± 11% atrial surface area) were adequate for analysis. Compared with adjudicators, the algorithm had a sensitivity of 84% for FA and 86% for RoA. There were 4 ± 2 FA and 2 ± 2 RoA per patient. FA occurred 8 ± 6 times during the 30‐second window (cumulative duration 8 ± 6 seconds). RoA occurred 5 ± 3 times (median 2, consecutive rotations) with a cumulative duration of 3 ± 2 seconds. Compared to patients without procedural AF termination, patients with termination had more FA ablated (75% vs 38%, P = 0.006). AF termination was not predicted by percentage of RoA ablated although there was a trend towards a higher percentage of left atrial RoA ablated (P = 0.06). Conclusion: An automated algorithm had high sensitivity for FA and RoA. Acute AF termination was associated with FA ablation but not RoA ablation. Future studies need to define the significance of FA and RoA and whether they are overlapping or separate mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The ConfiDENSE™ module (Carto3 v4) allows rapid annotation of endocardial electrograms acquired by multielectrode (ME) mapping. However, its accuracy in assessing atrial voltages is unknown. Methods and results: Two ConfiDENSE™ left atrial voltage maps were created during continuous pacing in 20 patients undergoing catheter ablation for persistent AF using a ME lasso catheter and a contact force (CF) sensing ablation catheter. The automated tissue proximity indicator (TPI) filter was then applied to the ME map to yield a TPI map. Reference maps (RM) were created offline by a blinded observer by manually assessing all points against fidelity criteria. Bipolar voltages and proportion of low voltage points (< 0.5 mV) derived from the ME, CF, and TPI maps were compared with those derived from the RM. Note that 853 ± 365 points, 252 ± 184 points, and 144 ± 73 were collected for ME, TPI, and CF maps, respectively, and 429 ± 153 points were included in the RM. Voltages with CF and TPI maps were similar to those with RM (1.57 ± 0.47 mV vs. 1.63 ± 0.31 mV, P = 0.57 and 1.50 ± 0.38 mV vs. 1.63 ± 0.31 mV, P = 0.07, respectively), whereas ME maps showed a significantly lower mean voltage (1.00 ± 0.22 mV, P < 0.001). As compared to RM maps (17 ± 8%), low voltage points were significantly overestimated by the ME maps (50 ± 9% (P < 0.001) and TPI maps (28 ± 13% (P < 0.001), but not by the CF maps (22 ± 14%, P = 0.17). Conclusion: Application of the TPI filter to ConfiDENSE maps significantly increases the quality of the voltage data, conserving a reasonable point density, but still overestimates low voltage points as compared to CF‐sensing maps or maps reviewed manually. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Dominant frequency (DF) derived from fast Fourier transform (FFT) analysis has failed to guide atrial fibrillation (AF) ablation since it cannot guarantee temporal stability. Continuous wavelet transform (CWT) analysis is another frequency analysis that can show the temporal stability of a frequency. Methods and results: Forty‐four consecutive patients with persistent AF (PeAF) underwent pulmonary vein (PV) isolation (PVI) as the first‐time catheter ablation. The PVs and left atrium were mapped and electrograms (EGMs) were recorded for 30 seconds at each site. Pseudo‐frequency (PF) and coefficient of variation (CV) were calculated by CWT analysis. A PF with CV ≤ 10 was defined as a temporally stable PF (sPF). DF was also calculated by traditional FFT analysis from the first 5 seconds of the recorded EGMs. The highest sPF was shown inside the PVs in 20 patients (PV group), and at the non‐PV sites in 24 patients (non‐PV group). During the follow‐up period of 15.3 ± 4.4 months, the ablation success rate in the PV group was significantly higher than that in the non‐PV group (90% vs. 62%, P = 0.023). The location of the highest DF did not have a significant effect on ablation success rate between inside the PVs and at the non‐PV sites. Conclusion: PVI results for PeAF were significantly worse for patients with highest sPF at the non‐PV sites compared to patients with highest sPF sites inside the PVs. CWT analysis during AF could be used to verify whether PVI alone is sufficient for the first‐time catheter ablation in patients with PeAF. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Recent studies suggest that atrial fibrillation (AF) is maintained by electrical activity arising from focal sources. We sought to test whether catheter ablation that targets focal sources can improve on current ablation protocols for persistent AF. Methods and results: In patients with persistent AF whose AF did not terminate with pulmonary vein (PV) isolation, the left atrium was mapped with a 20‐pole high‐density mapping catheter using CARTO®3 navigation. If a site demonstrated centrifugal activation over at least three consecutive cycles, it was deemed a focal source and ablated. If AF remained, defragmentation was performed until AF was terminated. Freedom from atrial tachyarrhythmia was compared between the study patients and propensity score matched historical controls who had undergone conventional stepwise ablation. Of the 68 study patients, 2.9 ± 1.9 focal sources were identified in 60 patients. Focal sources displayed transient centrifugal activation patterns for a median of six consecutive cycles. Total radiofrequency duration was shorter in the study group (62 ± 16 minutes vs. 75 ± 24 minutes, P = 0.0003). During a 1‐year follow‐up period, 39 (57%) and 26 (38%) patients were free from atrial tachyarrhythmias in the absence of antiarrhythmic drugs in the study and control groups, respectively (hazard ratio: 1.85, 95% confidence interval: 1.17–2.96, P = 0.009). Improvement of clinical outcome was mainly driven by a decrease in recurrence of atrial tachycardia in the study patients (22% vs. 40%, P = 0.047). Conclusion: The results of this study suggest that focal sources are appropriate ablation targets in addition to the PVs in persistent AF. [ABSTRACT FROM AUTHOR]

Abstract: Entrainment mapping enables the diagnosis and characterization of reentrant arrhythmias from analysis of the specific interaction between pacing maneuvers and tachycardia. Described 40 years ago, the implementation and interpretation of pacing maneuvers to entrain tachycardias has evolved into an indispensible tool for diagnosis and mapping reentrant cardiac arrhythmias. For complex re‐entry pathways entrainment mapping allows determination of the relation of pacing sites to the re‐entry circuit and discrimination of relevant re‐entry parts from bystander areas. Careful interpretation is needed to recognize misleading findings. The general physiology of re‐entry, and the application, interpretation, limitations, and pitfalls of entrainment maneuvers used for cardiac mapping is reviewed. [ABSTRACT FROM AUTHOR]

Background There have been advancements of sophisticated mapping systems used for ablation procedures over the last decade. Utilization of these novel mapping systems in combination with remote magnetic navigation (RMN) needs to be established. We investigated the new EnSite Precision mapping system (St. Jude Medical, Inc., St. Paul, MN, USA), which collects magnetic data for checking navigation field stability and is built on an open platform, allowing physicians to choose diagnostic and ablation catheters. We address its compatibility with RMN. Objective To assess the clinical utility of a novel 3D mapping system (EnSite Precision mapping system) combined with RMN (Niobe ES, Stereotaxis, Inc., St. Louis, MO, USA) for atrial fibrillation (AF) ablation. Methods In this prospective nonrandomized study, two groups of patients were treated in our center for drug refractory AF. Patients were consecutively enrolled in each group. Group A (n = 35, 14 persistent AF [PsAF]) was treated using the novel 3D mapping system combined with RMN. Group B (n = 38, 16 PsAF) was treated using Carto®3 (Biosense Webster, Inc., Diamond Bar, CA, USA) combined with RMN. In Group A, the left atrium (LA) was mapped with a circular magnetic catheter manually and was then replaced by a RMN ablation catheter. At the end of the procedures in Group A, the circular catheter was used for confirming field stability. In Group B, an ablation catheter was controlled by RMN to perform both LA mapping and ablation. All patients underwent pulmonary vein antrum isolation. Additional complex fractionated atrial electrograms (CFAEs) ablation was performed for PsAF. Procedural, ablation, and fluoroscopy times were recorded and complications were assessed. Results Electrophysiological end points were achieved in all patients. Using the novel mapping system, LA mapping time was fast (308 ± 60 seconds) with detailed anatomy points (178,831 ± 70,897) collected and magnetic points throughout LA. At the end of the procedures in Group A, the LA model was confirmed to be stable and its location was within the distance threshold (1 mm). Procedure time (117.9 ± 29.6 minutes vs. 119.2 ± 29.7 minutes, P = 0.89), fluoroscopy time (6.1 ± 2.4 minutes vs. 4.8 ± 2.2 minutes, P = 0.07), and ablation time (28.0 ± 12.9 minutes vs. 27.9 ± 15.8 minutes, P = 0.98) were similar in Group A versus Group B, respectively. No complications occurred in either group. Conclusions LA mapped by the novel system is stable and reliable. Combined with RMN, it could be effectively used for AF ablation without impacting overall procedural times. [ABSTRACT FROM AUTHOR]

The article presents the discussion on development of the electroanatomic mapping technology allowing for precisely localizing the mapping catheter. Topics include fractionating electrograms reducing excitability and prolonged dispersion of the recovery often associated with reentrant tachyarrhythmias; and measured bipolar voltage reflecting the sum of the current flow recorded by the electrodes.

Introduction One question for the technological advancement of catheter ablation of atrial fibrillation (AF) is whether a creative new concept can combine and even improve the diagnostic mapping options of single-tip and basket catheters with the simplicity of the use of balloon catheters for ablation. Herein, we describe the first in-human experience with a single catheter offering such a complete solution. Methods and results A new catheter (Globe®) with a distal multielectrode array consisting of 16 ribs with 122 gold-plated electrodes was used. Each electrode can ablate, pace, and can measure tissue contact, temperature, current, and intracardiac electrograms. The Globe was deployed and removed without difficulty in all 3 patients. Complete pulmonary vein isolation (PVI) was achieved in all 12 veins. In 10 veins, PVI was achieved with a single placement in front of the respective vein ('single circle isolation'). In one subject, the device was repositioned due to the esophagus location. In the other subject, a single gap was observed after circumferential ablation of the right inferior PV. After precise gap identification, the device was adjusted slightly for improved contact at that region, and reablation resulted in immediate PVI. Conclusions PVI isolation could be performed with the new multielectrode array Globe in all 12 PVs offering the option for easy handling and fast 'single-shot' PVI. Several continuously updated mapping types from 122 electrodes even in real time during ablation demonstrate the capability to go beyond PVI for voltage mapping plus substrate modification, and for rotor mapping plus rotor ablation. [ABSTRACT FROM AUTHOR]

Introduction Template-matching algorithms are routinely used in the catheter ablation of patients with premature ventricular contractions (PVCs). However, systematic analysis of the accuracy and spatial resolution of such systems is lacking. Therefore, the aim of this evaluation was to perform a systematic in vivo validation of performance of a novel automated template-matching algorithm. Methods and results In a porcine model, paced beats simulating PVCs from different origins were investigated. The ability to discriminate between sinus rhythm and PVCs was tested by simulating PVCs using sequential pacing from different cardiac chambers. The accuracy of the algorithm in correctly classifying PVCs was reviewed by an independent investigator. In addition, the spatial resolution of pace matching was evaluated by assessing the QRS morphology discrimination at a distance of 0, 2, 4, and 6 mm of a simulated PVCs focus. The specificity of the algorithm for recognizing simulated PVCs was 99.6% and the sensitivity was 85.3%. There was a significant difference in the discrimination metric discrimination metric (with 0% being a perfect match and 100% being no correlation) between PVC origin (median 0%, interquartile range (IQR) 0-2%) versus at 2 mm (5%, IQR 2-7%), 4 mm (16%, IQR 11-21%), and 6 mm (24%, IQR 19-28%, P < 0.001 for all). The c-statistic for discrimination between PVC origin and a distance ≥ 2 mm was 0.93. Conclusions Automated template matching had high specificity and sensitivity, with good spatial discrimination and a pace-mapping resolution in range of 2 mm. Clinical application of this algorithm may assist in the interventional treatment of patients with PVCs. [ABSTRACT FROM AUTHOR]

Novel Mapping Technique for AF Introduction Identification of wavefront propagation pattern during AF remains challenging in ablation procedures. We sought to test a novel combination of a new mapping technology called Ripple Map and high-density mapping to distinguish focal and reentrant activation during atrial fibrillation (AF). Methods and Results Subjects were patients undergoing ablation for persistent AF. If AF remained after isolation of the pulmonary veins, the left atrium (LA) was mapped by a high-density mapping catheter for later analysis, after which ablation was continued using a conventional stepwise approach. After the procedure, electrograms from the high-density mapping catheter were analyzed using Ripple Map, which is a new feature in the CARTO®3, and type of activation on ≥3 consecutive AF cycles was determined. High-density mapping was performed on 569 sites in 45 patients (13 ± 3 sites per patient). AF wavefront propagation determined by Ripple Map was in good agreement with analysis of manual annotation of bipolar electrograms. Ripple Map's representation of wavefront activation pattern, which could include local as well as far-field activity, allowed us to identify focal activation in 64 (11%) sites and 1 (0.2%) reentrant activation site. Radiofrequency delivery in atrial regions with activation sites identified as focal by Ripple Map resulted in termination of AF more often than regions without focal activation (22% vs. 7%, P = 0.015). Conclusion This study demonstrated that Ripple Map enabled quick identification of AF wavefront activation pattern, potentially being helpful for determining ablation targets in persistent AF. [ABSTRACT FROM AUTHOR]

Voltage Differences With Multielectrode Mapping Introduction Bipolar voltage criteria to delineate left atrial (LA) scar have been derived using point-by-point (PBP) contact electroanatomical mapping. It remains unclear how PBP-derived LA scar correlates with multielectrode fast automated mapping (ME-FAM) derived scar. We aimed to correlate scar and bipolar voltages from LA maps created using PBP versus ME-FAM. Methods and Results In consecutive patients undergoing repeat AF ablation, 2 separate LA maps were created using PBP and ME-FAM during sinus rhythm before ablation. Contiguous areas in the LA with a bipolar voltage cutoff of ≤0.2 mV represented dense scar; LA scar percentage was calculated for each map. Each LA shell was divided into 9 regions and each region further subdivided into 4 quadrants for additional analysis; mean voltages of all points obtained using PBP versus ME-FAM in each region were compared. Forty maps (20 PBP: mean 228.5 ± 95.6 points; 20 ME-FAM: 923.0 ± 382.6 points) were created in 20 patients. Mapping time with ME-FAM was shorter compared with PBP (13.3 ± 5.3 vs. 34.4 ± 13.1 minutes; P < 0.001). Mean LA scar percentage was higher with PBP compared with ME-FAM (15.5 ± 17.1% vs. 12.8 ± 17.6%; P = 0.04). Mean PBP voltage distribution was lower (compared with ME-FAM) in the septum (0.95 ± 0.73 vs. 1.46 ± 0.99 mV; P = 0.009), posterior wall (0.84 ± 0.42 vs. 1.40 ± 0.83 mV; P = 0.0008), roof (0.78 ± 0.80 vs. 1.39 ± 1.09 mV; P = 0.0003), and right PV-LA junction (0.34 ± 0.25 vs. 0.59 ± 0.50 mV; P = 0.01) regions, while voltages were similar in all other LA regions (all P > 0.05). Conclusions In AF patients undergoing repeat ablation, bipolar voltage is greater in certain LA segments with ME-FAM compared with PBP mapping. [ABSTRACT FROM AUTHOR]

A New CARTO Software for Ablating Ventricular Arrhythmias Introduction A new imaging software (CARTO® Segmentation Module, Biosense Webster) allows preprocedural 3-D reconstruction of all heart chambers based on cardiac CT. We describe our initial experience with the new module during ablation of ventricular arrhythmias. Methods and Results Eighteen consecutive patients with idiopathic ventricular arrhythmias or ischemic ventricular tachycardia (VT) were studied. In the latter group, a combined endocardial and epicardial ablation was performed. Of the 14 patients with idiopathic arrhythmias, 12 were ablated in the outflow tract (OT), 1 in the midseptal left ventricle, and 1 at the left posterior fascicular area; acute successful ablation was achieved in 11 (78.6%) patients. The procedure was discontinued due to close proximity of the arrhythmia origin to the coronary arteries (CA) in 2 patients. Acute successful uncomplicated ablation was achieved in all 4 patients with ischemic VT. During ablation in the coronary cusps commissures, the CARTO® Segmentation Module accurately defined the cusps anatomy. The precise anatomic location provided by the module assisted in successfully ablating when information from activation mapping was not optimal, by ablating at the opposite side of the cusps. In addition, by demonstrating the precise location of the CA, it allowed safe ablation of arrhythmias that originated in close proximity to the CA both in the OT area and the epicardium, eliminating the need for repeat angiography. Conclusions The CARTO® Segmentation Module is useful for accurate definition of the exact anatomic location of ventricular arrhythmias and for safely ablating them especially in close proximity to the CA. [ABSTRACT FROM AUTHOR]