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Introduction: Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. Methods and Results: LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD‐Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low‐voltage as 0.1−0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t‐testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low‐voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001). Conclusion: Low‐voltage, high‐PF areas may be critical targets during catheter ablation of atypical atrial flutter. [ABSTRACT FROM AUTHOR]

Introduction: Clinical outcomes of long‐term ventricular septal pacing (VSP) without His‐Purkinje capture remain unknown. This study evaluated the differences in clinical outcomes between conduction system pacing (CSP), VSP, and right ventricular pacing (RVP). Methods: Consecutive patients with bradycardia indicated for pacing from 2016 to 2022 were prospectively followed for the clinical endpoints of heart failure (HF)‐hospitalizations and all‐cause mortality at 2 years. VSP was defined as septal pacing due to unsuccessful CSP implant or successful CSP followed by loss of His‐Purkinje capture within 90 days. Results: Among 1016 patients (age 73.9 ± 11.2 years, 47% female, 48% atrioventricular block), 612 received RVP, 335 received CSP and 69 received VSP. Paced QRS duration was similar between VSP and RVP, but both significantly longer than CSP (p <.05). HF‐hospitalizations occurred in 130 (13%) patients (CSP 7% vs. RVP 16% vs. VSP 13%, p =.001), and all‐cause mortality in 143 (14%) patients (CSP 7% vs. RVP 19% vs. VSP 9%, p <.001). The association of pacing modality with clinical events was limited to those with ventricular pacing (Vp) > 20% (pinteraction <.05). Adjusting for clinical risk factors among patients with Vp > 20%, VSP (adjusted hazard ratio [AHR]: 4.74, 95% confidence interval [CI]: 1.57–14.36) and RVP (AHR: 3.08, 95% CI: 1.44‐6.60) were associated with increased hazard of HF‐hospitalizations, and RVP (2.52, 95% CI: 1.19–5.35) with increased mortality, compared to CSP. Clinical endpoints did not differ between VSP and RVP with Vp > 20%, or amongst groups with Vp < 20%. Conclusion: Conduction system capture is associated with improved clinical outcomes. CSP should be preferred over VSP or RVP during pacing for bradycardia. [ABSTRACT FROM AUTHOR]

Introduction: During atrial fibrillation ablation (AFA), achievement of first pass isolation (FPI) reflects effective lesion formation and predicts long‐term freedom from arrhythmia recurrence. We aim to determine the clinical and procedural predictors of pulmonary vein FPI. Methods: We reviewed AFA procedures in a multicenter prospective registry of AFA (REAL‐AF). A multivariate ordinal logistic regression, weighted by inverse proceduralist volume, was used to determine predictors of FPI. Results: A total of 2671 patients were included with 1806 achieving FPI in both vein sides, 702 achieving FPI in one, and 163 having no FPI. Individually, age, left atrial (LA) scar, higher power usage (50 W), greater posterior contact force, ablation index >350 posteriorly, Vizigo™ sheath utilization, nonstandard ventilation, and high operator volume (>6 monthly cases) were all related to improved odds of FPI. Conversely sleep apnea, elevated body mass index (BMI), diabetes mellitus, LA enlargement, antiarrhythmic drug use, and center's higher fluoroscopy use were related to reduced odds of FPI. Multivariate analysis showed that BMI > 30 (OR 0.78 [0.64–0.96]) and LA volume (OR per mL increase = 1.00 [0.99–1.00]) predicted lower odds of achieving FPI, whereas significant left atrial scarring (>20%) was related to higher rates of FPI. Procedurally, the use of high power (50 W) (OR 1.32 [1.05–1.65]), increasing force posteriorly (OR 2.03 [1.19–3.46]), and nonstandard ventilation (OR 1.26 [1.00–1.59]) predicted higher FPI rates. At a site level, high procedural volume (OR 1.89 [1.48–2.41]) and low fluoroscopy centers (OR 0.72 [0.61–0.84]) had higher rates of FPI. Conclusion: FPI rates are affected by operator experience, patient comorbidities, and procedural strategies. These factors may be postulated to impact acute lesion formation. [ABSTRACT FROM AUTHOR]

Introduction: Active‐fixation leads have been associated with higher incidence of cardiac perforation. Large series specifically evaluating radiographic predictors of right ventricular (RV) lead perforation are lacking. Methods: We conducted a retrospective observational study including 1691 consecutive patients implanted with an active fixation pacing and defibrillator lead at our institution between January 2015 and January 2021. Fourteen patients who had clinically relevant RV perforation caused by pacemaker and implantable cardioverter‐defibrillator leads were included in the study. Results: Univariate and multivariate analyses were used to identify predictors of RV perforation. In multivariate analysis, lead slack score (odds ratio [OR]: 3.694, 95% confidence interval [CI]: 1.066–12.807; p =.039), change in lead slack height (OR: 1.218, 95% CI: 1.011–1.467; p =.038) and width (OR: 1.253, 95% CI: 1.120–1.402; p =.001), left ventricular ejection fraction (OR: 0.995, 95% CI: 0.910–1.088; p =.032) were independent predictors of RV perforation. Conclusion: Fluoroscopic predictors of RV perforation associated with RV lead can be easily determined during implantation. Identification of these predictors may prevent the sequelae of RV perforation associated with active‐fixation leads. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) is an established treatment strategy for atrial fibrillation (AF). To improve PVI efficacy and safety, high‐power short‐duration (HPSD) ablation and pulsed‐field ablation (PFA) were recently introduced into clinical practice. This study aimed to determine the extent of myocardial injury and systemic inflammation following PFA, HPSD, and standard RFA using established biomarkers. Methods: We included 179 patients with paroxysmal AF receiving first‐time PVI with different ablation technologies: standard RFA (30–40 W/20–30 s, n = 52), power‐controlled HPSD (70 W/5–7 s, n = 60), temperature‐controlled HPSD (90 W/4 s, n = 32), and PFA (biphasic, bipolar waveform, n = 35). High‐sensitivity cardiac troponin T (hs‐cTnT), creatine kinase (CK), CK MB isoform (CK‐MB), and white blood cell (WBC) count were determined before and after ablation. Results: Baseline characteristics were well‐balanced between groups (age 63.1 ± 10.3 years, 61.5% male). Postablation hs‐cTnT release was significantly higher with PFA (1469.3 ± 495.0 ng/L), HPSD‐70W (1322.3 ± 510.6 ng/L), and HPSD‐90W (1441.2 ± 409.9 ng/L) than with standard RFA (1045.9 ± 369.7 ng/L; p <.001). CK and CK‐MB release was increased with PFA by 3.4‐fold and 5.8‐fold, respectively, as compared to standard RFA (p <.001). PFA was associated with the lowest elevation in WBC (Δ1.5 ± 1.5 × 109/L), as compared to standard RFA (Δ3.8 ± 2.5 × 109/L, p <.001), HPSD‐70W (Δ2.7 ± 1.7 × 109/L, p =.037), and HPSD‐90W (Δ3.6 ± 2.5 × 109/L, p <.001). Conclusion: Among the four investigated ablation technologies, PFA was associated with the highest myocardial injury and the lowest inflammatory reaction. [ABSTRACT FROM AUTHOR]

Introduction: Cryoballoon ablation (CBA) of the left atrial (LA) roof in addition to a pulmonary vein isolation has been expected to improve the clinical outcomes post‐atrial fibrillation (AF) ablation. We demonstrated the characteristics and efficacy of CBA of the LA roof through our experience with a large volume of procedures. Methods: Among 1036 AF ablation procedures with CBA of the LA roof, 834 patients who underwent a de novo ablation were analyzed. Results: Complete LA roof line conduction block was obtained in 767 patients (92.0%) solely by CBA (Group A). Compared with the other patients (Group B), the mean nadir balloon temperature during CBA of the LA roof (−44.5 ± 5.6°C for Group A vs. −40.5 ± 7.5°C for Group B, p <.01) and number of cryoballoon applications during the LA roof ablation with a circular mapping catheter located in the left superior pulmonary vein (1.3 ± 0.8 for Group A vs. 1.6 ± 1.0 for Group B, p =.02) were significantly lower in Group A. A multivariate analysis revealed that those were predictors of a complete LA roof conduction block after only CBA. The 1‐year Kaplan–Meier atrial arrhythmia free rate estimates were 80.6% for Group A and 59.0% for Group B (p <.01). Conclusion: Complete LA roof line conduction block could be obtained with a cryoballoon without touch‐up ablation in most cases. The LA roof CBA with a circular mapping catheter located in the right superior pulmonary vein was preferable to obtaining complete LA roof conduction block, which was important with regard to the clinical outcomes. [ABSTRACT FROM AUTHOR]

Introduction: Despite undergoing an index ablation, some patients progress from paroxysmal atrial fibrillation (PAF) to persistent AF (PersAF), and the mechanism behind this is unclear. The aim of this study was to investigate the predictors of progression to PersAF after catheter ablation in patients with PAF. Methods: This study included 400 PAF patients who underwent an index ablation between 2015 and 2019. The patients were classified into three groups based on their outcomes: Group 1 (PAF to sinus rhythm, n = 226), Group 2 (PAF to PAF, n = 146), and Group 3 (PAF to PersAF, n = 28). Baseline and procedural characteristics were collected, and predictors for AF recurrence and progression were evaluated. Results: The mean age of the patients was 58.4 ± 11.1 years, with 272 males. After 3 years of follow‐up, 7% of the PAF cases recurred and progressed to PersAF despite undergoing an index catheter ablation. In the multivariable analysis, a larger left atrial (LA) diameter and the presence of non‐pulmonary vein (PV) triggers during the index procedure independently predicted recurrence. Moreover, a larger LA diameter, the presence of non‐PV triggers, and a history of thyroid disease independently predicted AF progression. Conclusion: The progression from PAF to PersAF after catheter ablation is associated with a larger LA diameter, history of thyroid disease, and the presence of non‐PV triggers. Meticulous preprocedural evaluation, patient selection, and comprehensive provocation tests during catheter ablation are recommended. [ABSTRACT FROM AUTHOR]

Introduction: Atrial tachyarrhythmia recurrence during the blanking period (early ATA) after pulmonary vein isolation (PVI) is associated with an increased risk of later recurrence, but its relationship with pulmonary vein reconduction (PVR) is poorly understood. The objective of the present study was to evaluate the relationship between early ATA and PVR. Second, to provide data on the optimal blanking period by (a) evaluating how the predictive values of ATA for PVR are affected by blanking period duration, and (b) assessing the temporal development in atrial fibrillation (AF) burden. Methods: In this RACE‐AF substudy, 91 patients with paroxysmal AF undergoing PVI randomized to radiofrequency or cryoballoon ablation were included. All patients received an implantable cardiac monitor and underwent a protocol‐mandated repeat procedure after 4–6 months for assessment of PVR. ATA ≥ 30 s. ≤ 90 days after PVI constituted early ATA. Results: PVR was found in 37/54 (69%) patients with early ATA and in 11/37 (30%) patients without (p <.001). The positive predictive value of ATA for PVR was independent of blanking period duration (range 0–90 days). In both patients with and without PVR, AF burden was higher in the first month after PVI, but AF burden from the second month was similar to AF burden after the conventional blanking period. Conclusion: Early ATA indicates PVR, and the positive predictive value is independent of the blanking period duration. Altogether, the results of this study support substantially shortening the blanking period after PVI for paroxysmal AF. [ABSTRACT FROM AUTHOR]

Introduction: The use of flecainide and propafenone for medical cardioversion of atrial fibrillation (AF) and atrial flutter/intra‐atrial reentrant tachycardia (IART) is well‐described in adults without congenital heart disease (CHD). Data are sparse regarding their use for the same purpose in adults with CHD and in adolescent patients with anatomically normal hearts and we sought to describe the use of class IC drugs in this population and identify factors associated with decreased likelihood of success. Methods: Single center retrospective cohort study of patients who received oral flecainide or propafenone for medical cardioversion of AF or IART from 2000 to 2022. The unit of analysis was each episode of AF/IART. We performed a time‐to‐sinus rhythm analysis using a Cox proportional hazards model clustering on the patient to identify factors associated with increased likelihood of success. Results: We identified 45 episodes involving 41 patients. As only episodes of AF were successfully cardioverted with medical therapy, episodes of IART were excluded from our analyses. Use of flecainide was the only factor associated with increased likelihood of success. There was a statistically insignificant trend toward decreased likelihood of success in patients with CHD. Conclusions: Flecainide was more effective than propafenone. We did not detect a difference in rate of conversion to sinus rhythm between patients with and without CHD and were likely underpowered to do so, however, there was a trend toward decreased likelihood of success in patients with CHD. That said, medical therapy was effective in >50% of patients with CHD with AF. [ABSTRACT FROM AUTHOR]

Aims: To investigate the association of cardiac resynchronization therapy (CRT) on outcomes among participants with and without a history of atrial fibrillation (AF). Methods: Individual‐patient‐data from four randomized trials investigating CRT‐Defibrillators (COMPANION, MADIT‐CRT, REVERSE) or CRT‐Pacemakers (COMPANION, MIRACLE) were analyzed. Outcomes were time to a composite of heart failure hospitalization or all‐cause mortality or to all‐cause mortality alone. The association of CRT on outcomes for patients with and without a history of AF was assessed using a Bayesian‐Weibull survival regression model adjusting for baseline characteristics. Results: Of 3964 patients included, 586 (14.8%) had a history of AF; 2245 (66%) were randomized to CRT. Overall, CRT reduced the risk of the primary composite endpoint (hazard ratio [HR]: 0.69, 95% credible interval [CI]: 0.56–0.81). The effect was similar (posterior probability of no interaction = 0.26) in patients with (HR: 0.78, 95% CI: 0.55–1.10) and without a history of AF (HR: 0.67, 95% CI: 0.55–0.80). In these four trials, CRT did not reduce mortality overall (HR: 0.82, 95% CI: 0.66–1.01) without evidence of interaction (posterior probability of no interaction = 0.14) for patients with (HR: 1.09, 95% CI: 0.70–1.74) or without a history of AF (HR: 0.70, 95% CI: 0.60–0.97). Conclusion: The association of CRT on the composite endpoint or mortality was not statistically different for patients with or without a history of AF, but this could reflect inadequate power. Our results call for trials to confirm the benefit of CRT recipients with a history of AF. [ABSTRACT FROM AUTHOR]

Introduction: Intermuscular implantations of subcutaneous implantable cardioverter‐defibrillators (S‐ICD) have been recommended, but the position of the anterior border of the latissimus dorsi muscle (LDM) has not previously been evaluated in establishing an incision line to facilitate the intermuscular approach. The objective of this study is to evalua the position and trend of the anterior border of the LDM in patients who are candidates for implantable cardioverter‐defibrillators. Methods: The distance from the back to the anterior border of the LDM (A) and the anterior–posterior width of the chest wall (B) were measured on computed tomography retrospectively, and the ratio (=A/B) was used as the position of the anterior border of the LDM. In addition, the variability and factors affecting the values were evaluated. Results: An analysis was performed on 78 patients, and the position of the anterior border of the LDM (=A/B) exhibited a normal distribution, with a mean value of 0.53 ± 0.062 (0.41–0.69). The position of the anterior border of the LDM tended to be more anterior in younger, taller, male, primary prevention, nonheart failure, low brain natriuretic peptide level, and nondiabetic patients. Conclusion: The position of the anterior border of the LDM varied from case to case with variable results. Conventional incisions on the midaxillary line may be inappropriate for intermuscular implantations, and the position of the anterior border of the LDM should be evaluated in each individual case to establish the incision line. [ABSTRACT FROM AUTHOR]

Introduction: Various agents may be utilized to manage supraventricular tachycardia (SVT) in neonates and infants. Recently, sotalol has piqued interest given its reported success in managing neonates and infants with SVTs, especially with the intravenous formulation. While the manufacturer recommends using an age‐related nomogram in neonates and young infants to guide doses, clinical reports describe various dosing based on weight (mg/kg) or on body surface area (BSA) in mg/m2. Given the reported variation in clinical practice with regard to dosing in neonates, there is a gap in the literature and translation into clinical practice regarding applicability of the nomogram into clinical practice. The purpose of this study was to describe sotalol doses based on body weight and BSA in neonates for SVT. Methods: This is a single center retrospective study evaluating effective sotalol dosing from January 2011 and June 2021 (inclusive). Neonates who received intravenous (IV) or oral (PO) sotalol for SVT were eligible for inclusion. The primary outcome was to describe sotalol doses based on body weight and BSA. Secondary outcomes include comparison of doses to the manufacturer nomogram, description of dose titrations, reported adverse outcomes, and change in therapy. Two‐sided Wilcoxon signed‐rank tests were used to determine statistically significant differences. Results: Thirty‐one eligible patients were included in this study. The median (range) age and weight were 16.5 (1−28) days and 3.2 (1.8−4.9) kg, respectively. The median initial dose was 7.3 (1.9−10.8) mg/kg or 114.3 (30.9−166.7) mg/m2/day. Fourteen (45.2%) of patients required a dose increase for SVT control. The median dose required for rhythm control was 8.5 (2−14.8) mg/kg/day or 120.7 (30.9−225) mg/m2/day. Of note, the median recommended dose per manufacturer nomogram for our patients would have been 51.3 (16.2−73.8) mg/m2/day, which is significantly lower than both the initial dose (p <.001) and final doses (p <.001) utilized in our study. A total of 7 (22.9%) patients were uncontrolled on sotalol monotherapy using our dosing regimen. Two patients (6.5%) had reports of hypotension and one patient (3.3%) had a report of bradycardia requiring discontinuation of therapy. The average change in baseline QTC following sotalol initiation was 6.8%. Twenty‐seven (87.1%), 3 (9.7%), 1 (3.3%) experienced prolongation, no change, or a decrease in QTc, respectively. Conclusions: This study demonstrates that a sotalol strategy significantly higher than the manufacture dose recommendations are required for rhythm control in neonates with SVT. There were few adverse events reported with this dosing. Further prospective studies would be advantageous to confirm these findings. [ABSTRACT FROM AUTHOR]

Introduction: In patients receiving conduction system pacing (CSP), it is not well established how to program the sensed atrioventricular delay (sAVD), with respect to the type of capture obtained (selective, nonselective His‐bundle [HB] capture or left bundle branch [LBB] capture). The aim of this study was to acutely assess the effectiveness of an electrophysiology (EP)‐guided method for sAVD optimization by comparing it with the echocardiogram‐guided optimization. Methods and Results: Consecutive patients undergoing HB or LBB pacing were enrolled. The EP‐guided sAVD was defined as the sAVD leading to a PR interval of 150 ms on surface electrocardiogram (ECG). In HB pacing patients, EP‐guided sAVD was obtained subtracting the time from the onset of the P wave on ECG to the local atrial electrogram (EGM) recorded by the atrial lead (right atrial sensing latency, RASL) and the His‐ventricular interval from 150 ms; in LBB pacing patients, subtracting RASL from 150 ms. Transmitral flow assessment by pulsed wave Doppler was used to find the echo‐optimized sAVD by a modified iterative method. The discordance between the EP‐guided and the echo‐optimized sAVD was recorded. Results: Seventy‐one patients were enrolled: 12 with selective, 32 nonselective HB capture, and 27 LBB capture. Overall, the rate of concordance between the EP‐guided and the echo‐optimized sAVD was 71.8%, with no significant differences between the three groups. Conclusion: In CSP patients, an optimal sAVD can be programmed, in more than 70% of cases, considering only simple EGM intervals to obtain a physiological PR interval on surface ECG. [ABSTRACT FROM AUTHOR]

Introduction: Radiofrequency (RF) catheter ablation induces excitation recoverable myocardium around durable core lesions, and its distribution may be different depending on energy delivery methods. Methods and Results: In coronary perfusing porcine hearts, pacing threshold through the ventricle was measured using eight‐pole (1‐mm distance) needle electrodes vertically inserted into myocardium before, within 3 min after and 40 min after 40 W ablation with 10‐g catheter contact (Group 1: irrigation catheter for 15 s, Group 2: irrigation catheter for 40 s, Group 3: nonirrigation catheter for 15 s, Group 4: nonirrigation catheter for 40 s). Ablation was accomplished in all 12 ablations in Groups 1–3 whereas in 8/12 ablations in Group 4 because of high‐temperature rise. Within 3 min after ablation, 10.0 V pacing uncaptured electrodes were distributed from the surface to inside the myocardium, and its depth was deeper in 40 s than in 15 s ablation. 40 min after ablation, excitation recovery at one or more electrodes below the durable lesion was observed in all Groups. Excitation recovery electrodes were also observed on the surface in Group 1 but not the other Groups. Accordingly, the number of excitation‐recovered electrodes were larger in Group 1 than the other Groups. Conclusions: Regardless of the ablation methods, excitation recoverable myocardium was present around 1.0 mm below the durable lesions. Lesions created by short application time using an irrigation catheter may have included large excitation recoverable myocardium soon after ablation because of the presence of reversible myocardium on well‐irrigated myocardial surfaces. [ABSTRACT FROM AUTHOR]

Background: Lesion gaps assessed by late‐gadolinium enhancement magnetic resonance imaging (LGE‐MRI) are associated with the atrial fibrillation (AF) recurrence after pulmonary vein isolation. Animal studies have demonstrated that the catheter‐contact force (CF), stability, and orientation are strongly associated with lesion formation. However, the impact of those procedural factors on the lesion characteristics associated with AF recurrence has not been well discussed. Methods: A total of 30 patients with paroxysmal AF who underwent catheter ablation were retrospectively enrolled. Radiofrequency (RF) applications were performed with 35 W for 30 s in a point‐by‐point fashion under esophageal temperature monitoring. The inter‐lesion distance was 4 mm. The lesions were visualized by LGE‐MRI 3 months postprocedure and assessed by the LGE volume (ml), gap number (GN), and average gap length (AGL [mm]). The gaps were defined as nonenhancement sites of >4 mm. The procedural factors including the catheter‐CF, stability, and orientation were calculated on the NavX system. Results: Six (20%) of 30 patients had AF recurrences 12 months postablation. A univariate analysis demonstrated that the AGL was associated with AF recurrence (hazard ratio [HR]: 1.20, confidence interval [CI]: 1.03–1.42, p =.02). All AF recurrence were found in patients with an AGL of >7 mm. The catheter‐CF and stability were associated with an AGL of >7 mm, but not the orientation (CF—HR: 0.62, CI: 0.39–0.97, p =.038; stability—HR: 0.8, CI: 0.66–0.98, p =.027). Conclusions: RF ablation with a low CF and poor catheter stability has a potential risk of creating large lesion gaps associated with AF recurrence. [ABSTRACT FROM AUTHOR]

Introduction: Substrate‐based ablation for ventricular tachycardia (VT) using Ripple map (RM) is an effective treatment strategy for patients with ischemic cardiomyopathy but has yet to be evaluated in patients with nonischemic cardiomyopathy (NICMO). The aim of this study is to determine the feasibility and effectiveness of an RM‐based ablation for NICMO patients. Methods and Results: This was a single‐center, retrospective study including all NICMO patients undergoing VT ablation at St Vincent Hospital between January 1, 2018 and January 12, 2019. Retrospective RM analysis was performed on those that had a substrate‐based ablation to identify the location and number of Ripple channels as well as their proximity to ablation lesions. Thirty‐three patients met the inclusion criteria and had a median age of 65 (58, 73.5) with 15.2% of the population being female, and were followed for a median duration of 451 (217.5, 586.5) days. Of these patients, 23 (69.7%) had a substrate‐based ablation with a median procedural duration of 196.4 (186.8, 339) min, 1946 (517, 2750) points collected per map, and 277 (141, 554) points were within the scar. Two (8.6%) procedural complications occurred, and 7 (30.4%) patients had VT recurrence during follow‐up. RM analysis revealed an average of two Ripple channels and the patients without VT recurrence had ablation performed closer to the Ripple channels: 0 (0, 4.7) versus 14.3 (0, 23.5) cm; p =.02. Conclusion: An RM‐based substrate ablation can be performed in NICMO patients and ablation within Ripple channels is a predictor of VT freedom. [ABSTRACT FROM AUTHOR]

Background: Ventricular scar is traditionally highlighted on a bipolar voltage (BiVolt) map in areas of myocardium <0.50 mV. We describe an alternative approach using Ripple Mapping (RM) superimposed onto a BiVolt map to differentiate postinfarct scar from conducting borderzone (BZ) during ventricular tachycardia (VT) ablation. Methods: Fifteen consecutive patients (left ventricular ejection fraction 30 ± 7%) underwent endocardial left ventricle pentaray mapping (median 5148 points) and ablation targeting areas of late Ripple activation. BiVolt maps were studied offline at initial voltage of 0.50–0.50 mV to binarize the color display (red and purple). RMs were superimposed, and the BiVolt limits were sequentially reduced until only areas devoid of Ripple bars appeared red, defined as RM‐scar. The surrounding area supporting conducting Ripple wavefronts in tissue <0.50 mV defined the RM‐BZ. Results: RM‐scar was significantly smaller than the traditional 0.50 mV cutoff (median 4% vs. 12% shell area, p <.001). 65 ± 16% of tissue <0.50 mV supported Ripple activation within the RM‐BZ. The mean BiVolt threshold that differentiated RM‐scar from BZ tissue was 0.22 ± 0.07 mV, though this ranged widely (from 0.12 to 0.35 mV). In this study, septal infarcts (7/15) were associated with more rapid VTs (282 vs. 347 ms, p =.001), and had a greater proportion of RM‐BZ to RM‐scar (median ratio 3.2 vs. 1.2, p =.013) with faster RM‐BZ conduction speed (0.72 vs. 0.34 m/s, p =.001). Conversely, scars that supported hemodynamically stable sustained VT (6/15) were slower (367 ± 38 ms), had a smaller proportion of RM‐BZ to RM‐scar (median ratio 1.2 vs. 3.2, p =.059), and slower RM‐BZ conduction speed (0.36 vs. 0.63 m/s, p =.036). RM guided ablation collocated within 66 ± 20% of RM‐BZ, most concentrated around the RM‐scar perimeter, with significant VT reduction (median 4.0 episodes preablation vs. 0 post, p <.001) at 11 ± 6 months follow‐up. Conclusion: Postinfarct scars appear significantly smaller than traditional 0.50 mV cut‐offs suggest, with voltage thresholds unique to each patient. [ABSTRACT FROM AUTHOR]

Introduction: Critical isthmuses of atypical atrial flutters (AAFLs) are usually located at slow conduction areas that exhibit fractionated electrograms. We tested a novel software, intended for integration with a commercially available navigation system, that automatically detects fractionated electrograms, to identify the critical isthmus in patients with AAFL ablation. Methods and Results: All available patients were analyzed; 27 patients with 33 AAFLs were included. The PentaRay NAV catheter (Biosense Webster) was used for mapping. The novel software was retrospectively applied; fractionated points with duration ≥80 ms and bipolar voltage between 0.05 and 0.5 mV were highlighted on the surface of maps. In 10 randomly chosen AAFLs, an expert electrophysiologist evaluated the positive predictive value of the algorithm to detect true fractionation: 74.4%. We tested the capacity of the software to identify areas of fractionation (defined as clusters of ≥3 adjacent points with fractionation) at the critical isthmus of the AAFLs (defined using conventional mapping criteria). An area of fractionation was identified at the critical isthmus in 30 cases (91%). Globally, 144 areas of fractionation (median number per AAFL 4 [3–6]) were identified. Duration of the fractionation or the surface of the areas was not different between areas at critical isthmuses and the rest. Setting the fractionation score filter of the software in nine provided best performance. Conclusions: The novel software detected areas of fractionation at the critical isthmus in most AAFLs, which may help identify the critical isthmus in clinical practice. [ABSTRACT FROM AUTHOR]

Background: Obstructive sleep apnea (OSA) creates a complex substrate for atrial fibrillation (AF), which is refractory to many clinically available pharmacological interventions. We investigated atrial antiarrhythmogenic properties and ventricular electrophysiological safety of small‐conductance Ca2+‐activated K+ (SK)‐channel inhibition in a porcine model for obstructive respiratory events. Methods: In spontaneously breathing pigs, obstructive respiratory events were simulated by intermittent negative upper airway pressure (INAP) applied via a pressure device connected to the intubation tube. INAP was applied for 75 s, every 10 min, three times before and three times during infusion of the SK‐channel inhibitor AP14145. Atrial effective refractory periods (AERP) were acquired before (pre‐INAP), during (INAP) and after (post‐) INAP. AF‐inducibility was determined by a S1S2 atrial pacing protocol. Ventricular arrhythmicity was evaluated by heart rate adjusted QT‐interval duration (QT‐paced) and electromechanical window (EMW) shortening. Results: During vehicle infusion, INAP transiently shortened AERP (pre‐INAP: 135 ± 10 ms vs. post‐INAP 101 ± 11 ms; p =.008) and increased AF‐inducibility. QT‐paced prolonged during INAP (pre‐INAP 270 ± 7 ms vs. INAP 275 ± 7 ms; p =.04) and EMW shortened progressively throughout INAP and post‐INAP (pre‐INAP 80 ± 4 ms; INAP 59 ± 6 ms, post‐INAP 46 ± 10 ms). AP14145 prolonged baseline AERP, partially prevented INAP‐induced AERP‐shortening and reduced AF‐susceptibility. AP14145 did not alter QT‐paced at baseline (pre‐AP14145 270 ± 7 ms vs. AP14145 268 ± 6 ms, p =.83) or QT‐paced and EMW‐shortening during INAP. Conclusion: In a pig model for obstructive respiratory events, the SK‐channel‐inhibitor AP14145 prevented INAP‐associated AERP‐shortening and AF‐susceptibility without impairing ventricular electrophysiology. Whether SK‐channels represent a target for OSA‐related AF in humans warrants further study. [ABSTRACT FROM AUTHOR]

Introduction: BNP elevation in patients with AF is observed in the absence of heart failure; however, prior mechanistic studies have not included direct left atrial pressure measurements. This study sought to understand how emptying function of the left atrial appendage (LAA) and LAA dimension contributes to brain‐natriuretic peptide elevations (BNP) in atrial fibrillation (AF) accounting for left atrial pressure (LAP). Methods: 132 patients referredfor left atrial appendage occlusion (LAAO) were prospectively enrolled in this study. BNP levels and LAP were measured just before LAAO. Statistical analysis considered BNP, rhythm at time of procedure, LAP, LAA morphology, LAA size (ostial diameter, depth, volume), LAA emptying velocity, CHADS2‐VASc score, body mass index (BMI), left ventricular ejection fraction (LVEF), estimated glomerular filtration rate (eGFR), and obstructive sleep apnea (OSA) diagnosis as covariates. Results: Bivariate statistical analysis demonstrated positive associations with age, LAA ostial diameter, depth, and volume, LAP, AF status at time of measurement, OSA, and CHADS2‐VASc score. BNP was negatively associated with LVEF, eGFR, LAA emptying velocity and BMI. With multivariate logistic regression including LAP as covariate, significant relationships between BNP and AF/AFL(OR 1.99 [1.03, 3.85]), LAP (OR 1.13 [1.06, 1.20]), LAA diameter (OR 1.14 [1.03, 1.27]), LAA depth (OR 1.14 [1.07, 1.22]), and LAA emptying velocity (OR 0.97 [0.96,0.99]) were observed; however, no significant associations were seen with LAA morphology or CHADS2‐VASc score. Conclusions: BNP elevations in AF are associated with LAA size and function, but not CHADS2‐VASc score or appendage morphology after accounting for changes in LAP. [ABSTRACT FROM AUTHOR]

Introduction: Bipolar (BIP) radiofrequency (RF) ablation creates deep myocardial lesions but ideal energy application modes to treat ventricular arrhythmias originating from deep inside the thick myocardium have not been well established. An experimental study was performed to clarify whether high power and long application time BIP ablation were performable by impedance‐decline‐guide power control (PC) and whether it could create transmural lesions in the thick ventricle with a minimum risk of steam‐pop. Methods and Results: Perfused porcine ventricle (18.4 ± 2.3 mm) was placed in an experimental bath and BIP ablation (50 W) for 120 s was attempted with catheter contact of 30‐g using two protocols; fixed power (FP) and impedance‐decline‐guide PC. In the latter protocol, BIP ablation was started from 50 W, while the energy was decreased to 40–20 W according to the impedance decline during RF ablation. FP ablation was attempted in 30 applications and the transmural lesion was created in all 30, although steam‐pop occurred in 16/30 applications (53%). Low minimum impedance, large total impedance decline (TID), and %‐TID were associated with the steam‐pop occurrence. PC ablation was attempted in another 21 applications, and the transmural lesion was created in all 21 without steam‐pop. PC ablation was superior to FP ablation (21/21 vs. 14/30, p <.001) in the creation of a transmural lesion without resulting in steam‐pop. Conclusions: High power and long application time BIP ablation seems to be feasible according to the impedance‐decline‐guide approach, which could create transmural lesions in thick porcine ventricles with minimal risk of steam‐pop. [ABSTRACT FROM AUTHOR]

Introduction: Atrial fibrillation (AF) is the most common sustained arrhythmia in humans. The onset of the arrhythmia can significantly impair cardiac function. This hemodynamic deterioration has been explained by several mechanisms such as the loss of atrial contraction, shortening of ventricular filling, or heart rhythm irregularity. This study sought to evaluate the relative hemodynamic contribution of each of these components during in vivo simulated human AF. Methods: Twelve patients undergoing catheter ablation for paroxysmal AF were paced simultaneously from the proximal coronary sinus and the His bundle region according to prescribed sequences of irregular R−R intervals with the average rate of 90 and 130 bpm, which were extracted from the database of digital ECG recordings of AF from other patients. The simulated AF was compared to regular atrial pacing with spontaneous atrioventricular conduction and regular simultaneous atrioventricular pacing at the same heart rate. Beat‐by‐beat left atrial and left ventricular pressures, including LV dP/dT and Tau index were assessed by direct invasive measurement; beat‐by‐beat stroke volume and cardiac output (index) were assessed by simultaneous pulse‐wave doppler intracardiac echocardiography. Results: Simulated AF led to significant impairment of left ventricular systolic and diastolic function. Both loss of atrial contraction and heart rate irregularity significantly contributed to hemodynamic impairment. This effect was pronounced with increasing heart rate. Conclusion: Our findings strengthen the rationale for therapeutic strategies aiming at rhythm control and heart rate regularization in patients with AF. [ABSTRACT FROM AUTHOR]

Background: 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). Objective: Our aim was to validate an electrocardiographic marker of LVAs in the RVOT in patients with idiopathic outflow tract VAs. Methods: 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. Results: 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. Conclusion: LVAs were frequently present in patients with idiopathic VAs. ST‐segment elevation was the only independent predictor of their presence. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to evaluate the incidence of acute pericarditis following cardioneuroablation (CNA) and to compare this with patients undergoing left atrial (LA) radiofrequency ablation for atrial fibrillation (AF). Methods and Results: This is a single‐center prospective study. During the study period, CNA for vasovagal syncope was performed in 42 patients, pulmonary vein isolation (PVI) for paroxysmal AF in 46 patients, and posterior wall isolation (PWI) in addition to PVI for persistent AF in 22 patients. Pericarditis was reported by 18 (16.4%) patients overall: 1 (2.4%) patient in CNA group, 8 (17.4%) patients in PVI group, and 9 (40.9%) patients in PWI (p <.001). On univariable logistic regression analysis, CNA was associated with a lower risk of pericarditis (odds ratio 0.11, 95% confidence interval [CI] 0.01–0.97), while ablation of PWI plus PVI was associated with a higher risk of pericarditis compared with PVI (odds ratio 3.29, 95% CI 1.05–10.3). Conclusion: This study shows that pericarditis is extremely uncommon following CNA and is significantly less frequent than following AF ablation. This difference is likely related to the much lower amount of LA ablation necessary in this group. [ABSTRACT FROM AUTHOR]

Introduction: In patients with symptomatic permanent atrial fibrillation (PEAF) and narrow QRS, atrio‐ventricular junction ablation (AVJA) plus cardiac resynchronization therapy (CRT) is superior to medical therapy in reducing heart failure (HF) hospitalization and all‐cause mortality. To compare the mortality of a population of patients with HF, reduced EF (rEF), and PEAF treated with AVJA plus CRT with that of a contemporary cohort of patients in sinus rhythm (SR) with similar baseline characteristics. Methods and Results: In this prospective, multicentre, observational study, all‐cause mortality in a group of consecutive patients undergoing AVJA and implantable cardioverter‐defibrillator (ICD) combined with CRT implantation for HFrEF, narrow QRS, and PEAF with uncontrolled ventricular rate was compared with that of a contemporary cohort of patients in SR undergoing ICD implantation (not combined with CRT) for HFrEF and narrow QRS. Individual 1:1 propensity matching of baseline characteristics was performed. A total of 824 patients were enrolled. Propensity matching yielded 107 matched pairs. After a median follow‐up of 52 months, all‐cause mortality was similar in patients treated with AVJA plus CRT and in the control group (p =.434). In AVJA plus CRT patients, mortality was significantly lower than in control group patients with a history of paroxysmal/persistent AF (n = 45, p =.020), and similar to that of patients without a history of AF (n = 62, p =.459). Conclusions: After adjustment for patient characteristics, the long‐term prognosis of patients with HFrEF, narrow QRS, and PEAF who underwent AVJA plus CRT was similar to that of a population of patients in SR with similar characteristics. [ABSTRACT FROM AUTHOR]

Introduction: Vasodilator stress cardiovascular magnetic resonance (CMR) is a powerful diagnostic modality, but data toward its use in patients with permanent pacemakers (PPMs) or implantable cardioverter‐defibrillators (ICDs) is limited. Methods and Results: Patients with ICDs (>1% pacing) or PPMs who underwent regadenoson single photon emission computed tomography (SPECT) and all patients with ICDs or PPMs who underwent stress CMR were retrospectively identified. SPECT tests were analyzed for hemodynamic responses and new pacing requirements; CMR studies were examined for safety, device characteristics and programming, hemodynamic responses, and image quality. Changes from baseline were evaluated with the Related‐Samples Wilcoxon Signed Rank Test. Of 67 patients (median age 65 [IQR 58–72] years, 31 [46%] female, 31 [46%] Black), 47 underwent SPECT and 20 CMR. With regadenoson SPECT, 89% of patients experienced tachycardic responses above resting heart rates (+19 [13–32] beats per minute, p <.01). During stress CMR, 10 (50%) devices were asynchronously paced approximately 10 beats per minute above resting rates, and the remaining were temporarily deactivated. Those with asynchronous pacing had no changes in heart rates, whereas patients with deactivated devices had near uniform heart rate accelerations. Image quality was diagnostic in the majority of stress CMR sequences, with nonconditional ICDs contributing 40 of 57 (70%) of nondiagnostic segments. Conclusion: This data supports the safety of vasodilator stress CMR with promising diagnostic quality images in patients with CMR conditional ICDs and PPMs. Despite a near uniform tachycardic response to regadenoson in the SPECT environment, high rates of asynchronous pacing during vasodilator stress CMR did not result in competitive pacing or adverse arrhythmic events. Further studies are needed to validate these findings and confirm the diagnostic and prognostic performance of stress CMR in these individuals. [ABSTRACT FROM AUTHOR]

Introduction: Monitored anesthesia care (MAC) or general anesthesia (GA) can be used during catheter ablation (CA) of atrial fibrillation (AF). However, each approach may have advantages and disadvantages with variability in operator preferences. The optimal approach has not been well established. The purpose of this study was to compare procedural efficacy, safety, clinical outcomes, and cost of CA for AF performed with MAC versus GA. Methods: The study population consisted of 810 consecutive patients (mean age: 63 ± 10 years, paroxysmal AF: 48%) who underwent a first CA for AF. All patients completed a preprocedural evaluation by the anesthesiologists. Among the 810 patients, MAC was used in 534 (66%) and GA in 276 (34%). Ten patients (1.5%) had to convert to GA during the CA. Results: Although the total anesthesia care was longer with GA particularly in patients with persistent AF, CA was shorter by 5 min with GA than MAC (p < 0.01). Prevalence of perioperative complications was similar between the two groups (4% vs. 4%, p = 0.89). There was no atrioesophageal fistula with either approach. GA was associated with a small, ~7% increase in total charges due to longer anesthesia care. During 43 ± 17 months of follow‐up after a single ablation procedure, 271/534 patients (51%) in the MAC and 129/276 (47%) patients in the GA groups were in sinus rhythm without concomitant antiarrhythmic drug therapy (p = 0.28). Conclusion: With the participation of an anesthesiologist, and proper preoperative assessment, CA of AF using GA or MAC has similar efficacy and safety. [ABSTRACT FROM AUTHOR]

Introduction: Pulsed‐field ablation (PFA), an ablative method that causes cell death by irreversible electroporation, has potential safety advantages over radiofrequency ablation and cryoablation. Pulmonary vein (PV) isolation was performed in a porcine model to characterize safety and performance of a novel, fully‐integrated biphasic PFA system comprising a multi‐channel generator, variable loop circular catheter, and integrated PFA mapping software module. Methods: Eight healthy porcine subjects were included. To evaluate safety, multiple ablations were performed, including sites not generally targeted for therapeutic ablation, such as the right inferior PV lumen, right superior PV ostium, and adjacent to the esophagus and phrenic nerve. To evaluate the efficacy, animals were recovered, followed for 30(±3) days, then re‐mapped. Gross pathological and histopathological examinations assessed procedural injuries, chronic thrombosis, tissue ablation, penetration depth, healing, and inflammatory response. Results: All eight animals survived follow‐up. PV narrowing was not observed acutely nor at follow‐up, even when ablation was performed deep to the PV ostium. No injury was seen grossly or histologically in adjacent structures. All PVs were durably isolated, confirmed by bidirectional block at re‐map procedure. Histological examination showed complete, transmural necrosis around the circumference of the ablated section of right PVs. Conclusion: This preclinical evaluation of a fully‐integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation without collateral damage to adjacent structures, even when ablation was performed in more extreme settings than those used therapeutically. Histological staining confirmed complete transmural cell necrosis around the circumference of the PV ostium at 30 days. [ABSTRACT FROM AUTHOR]

Introduction: Ablation for atrioventricular nodal reentrant tachycardia (AVNRT) classically utilizes evaluation of signal morphology within the anatomic region of the slow pathway (SP), which involves subjectivity. Ripple mapping (RM; CARTO‐3© Biosense Webster Inc) displays each electrogram at its three‐dimensional coordinate as a bar changing in length according to its voltage–time relationship. This allows prolonged, low‐amplitude signals to be displayed in their entirety, helping identify propagation in low‐voltage areas. We set out to evaluate the ability of RM to locate the anatomic site of the SP and assess its use in guiding ablation for AVNRT. Methods: Patients ≤18 years with AVNRT in the EP laboratory between 2017 and 2021 were evaluated. RM was performed to define region of SP conduction in patients from 2019 to 2021, whereas standard electro‐anatomical mapping was used from 2017 to 2019. All ablations were performed using cryotherapy. Demographics, outcomes, and analysis of variance in number of test lesions until success was compared between groups. Results: A total of 115 patients underwent AVRNT ablation during the study; 46 patients were in the RM group and 69 were in the control group. There were no demographic differences between groups. All procedures, in both groups, were acutely successful. In RM group, 89% of first successful lesions were within 4 mm of the predicted site. There was significantly reduced variability in number of test lesions until success in the RM group (p =.01). Conclusion: RM is a novel technique that can help identify SP location, allowing for successful ablation of AVNRT with decreased variability. [ABSTRACT FROM AUTHOR]

Introduction: Dofetilide suppresses atrial fibrillation (AF) in a dose‐dependent fashion. The protective effect of AF against QTc prolongation induced torsades de pointe and transient post‐cardioversion QTc prolongation may result in dofetilide under‐dosing during initiation. Thus, the optimal timing of cardioversion for AF patients undergoing dofetilide initiation to optimize discharge dose remains unknown as does the longitudinal stability of QTc. The purpose of this study was to evaluate the impact of baseline rhythm on dofetilide dosing during initiation and assess the longitudinal stability of QTc‐all (Bazzett, Fridericia, Framingham, and Hodges) over time. Methods: Medical records of patients who underwent preplanned dofetilide loading at a tertiary care center between January 2016 and 2019 were reviewed. Results: A total of 198 patients (66 ± 10 years, 32% female, CHADS2‐Vasc 3 [2–4]) presented for dofetilide loading in either AF (59%) or sinus rhythm (SR) (41%). Neither presenting rhythm, nor spontaneous conversion to SR impacted discharge dose. The cumulative dofetilide dose before cardioversion moderately correlated (r =.36; p =.0001) with discharge dose. Postcardioversion QTc‐all prolongation (p <.0001) prompted discharge dose reduction (890 ± 224 mcg vs. 552 ± 199 mcg; p <.0001) in 30% patients. QTc‐all in SR prolonged significantly during loading (p <.0001). All patients displayed QTc‐all reduction (p <.0001) from discharge to short‐term (46 [34–65] days) that continued at long‐term (360 [296–414] days) follow‐ups. The extent of QTc‐all reduction over time moderately correlated with discharge QTc‐all (r =.54–0.65; p <.0001). Conclusion: Dofetilide initiation before cardioversion is equivalent to initiation during SR. Significant QTc reduction proportional to discharge QTc is seen over time in all dofetilide‐treated patients. QTc returns to preloading baseline during follow‐up in patients initiated in SR. [ABSTRACT FROM AUTHOR]

Introduction: Bradyarrhythmias are an established red flag for storage cardiac conditions including Anderson–Fabry disease (AFD). The prevalence of bradyarrhythmias requiring a pacemaker (PM) and their timing in AFD is unresolved. Methods: We evaluated the prevalence and predictors of PM requirement in a large AFD cohort, investigating the occurrence of bradyarrhythmias as initial versus late manifestation. We retrospectively evaluated 82 consecutive AFD patients referred to our multidisciplinary referral center from 1994 to 2020 with a median follow‐up of 6.9 years, identifying those requiring pacing. Univariable analysis was performed to identify cardiac features associated with PM implantation. Results: Five of 82 (6%) AFD patients required PM implantation (5/39, i.e., 13% of those with cardiac involvement), always in the context of advanced cardiomyopathy. In none, bradyarrhythmias were the presenting feature. Indications included sick sinus syndrome in three patients, advanced atrioventricular block in two patients. QRS prolongation during follow‐up strongly correlated with the onset of bradyarrhythmias. Conclusion: Severe bradyarrhythmias are relatively frequent in patients with AFD cardiomyopathy, but do not represent a mode of presentation, occurring late in the disease course and always in the context of advanced cardiac involvement. Monitoring QRS variations over time may help to identify patients requiring pacing. [ABSTRACT FROM AUTHOR]

Introduction: Different methods are used for atrial fibrillation (AF) cycle length (CL) measurement with variable results. Previous studies of pulmonary vein (PV) CL measurement showed contradictory results on predicting PV isolation (PVI) efficacy. A novel simple method of measuring the average of 10 consecutive Fastest Atrial Repetitive Similar morphology signal (FARS10)‐CL to characterize local atrial activity rate was evaluated prospectively. Methods: The intra‐observer reproducibility of FARS10‐CL and traditional AF‐CL measurement of continuously fragmented coronary sinus (CS) signals were tested. We prospectively enrolled 100 consecutive patients (62 ± 10 years, 72% male) undergoing wide antral PVI only ablation for persistent AF, measured PV‐FARS10‐CLs, and evaluated long‐term outcome. Results: The Kendall area correlation between repeated traditional AF‐CL measurements was −0.006 and between repeated FARS10‐CL measurements in the right and left atrial appendages, CS and PVs were 0.944, 0.859, 0.882, 0.675–0.955, respectively. Patients with recurrent atrial tachyarrhythmia had significantly longer fastest PV‐FARS10‐CL (172 ± 41 vs. 156 ± 41 ms, p =.047). Patients with high burden of spontaneous low‐voltage zone (LVZ) had significantly longer fastest PV‐FARS10‐CL. Freedom from recurrent tachyarrhythmia at 24 months was 85% versus 59% in patients with fastest PV‐FARS10‐CL ≤ 140 versus >140 ms, p =.0018, respectively. In multivariable analysis fastest PV‐FARS10‐CL ≤ 140 ms was the only significant predictor of freedom from recurrent tachyarrhythmia. Conclusions: FARS10‐CL measurements have a high reproducibility in contrast to traditional AF‐CL measurement of continuously fragmented CS signals. Patients with high burden of LVZ have longer fastest PV‐FARS10‐CLs. Fastest PV‐FARS10‐CL ≤ 140 ms is associated with a high success of wide antral PVI‐only ablation approach in persistent AF. [ABSTRACT FROM AUTHOR]

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]

Introduction: Before ablation, predicting the site of origin (SOO) of outflow tract ventricular arrhythmia (OTVA), can inform patient consent and facilitate appropriate procedural planning. We set out to determine if OTVA variability can accurately predict SOO. Methods: Consecutive patients with a clear SOO identified at OTVA ablation had their prior 24‐h ambulatory ECGs retrospectively analysed (derivation cohort). Percentage ventricular ectopic (VE) burden, hourly VE values, episodes of trigeminy/bigeminy, and the variability in these parameters were evaluated for their ability to distinguish right from left‐sided SOO. Effective parameters were then prospectively tested on a validation cohort of consecutive patients undergoing their first OTVA ablation. Results: High VE variability (coefficient of variation ≥0.7) and the presence of any hour with <50 VE, were found to accurately predict RVOT SOO in a derivation cohort of 40 patients. In a validation cohort of 29 patients, the correct SOO was prospectively identified in 23/29 patients (79.3%) using CoV, and 26/29 patients (89.7%) using VE < 50. Including current ECG algorithms, VE < 50 had the highest Youden Index (78), the highest positive predictive value (95.0%) and the highest negative predictive value (77.8%). Conclusion: VE variability and the presence of a single hour where VE < 50 can be used to accurately predict SOO in patients with OTVA. Accuracy of these parameters compares favorably to existing ECG algorithms. [ABSTRACT FROM AUTHOR]

Background: The impact of comorbid disease states on the development of atrial and ventricular arrhythmias in patients with hypertrophic cardiomyopathy (HCM) remains unresolved. Objective: Evaluate the association of comorbidities linked to arrhythmias in other cardiovascular diseases (e.g., obesity, systemic hypertension, diabetes, obstructive sleep apnea, renal disorders, tobacco, and alcohol use) to atrial fibrillation (AF) and sudden cardiac death (SCD) events in a large cohort of HCM patients. Methods: A total of 2269 patients, 54 ± 15 years of age, 1392 males, were evaluated at the Tufts HCM Institute between 2004 and 2018 and followed for an average of 4 ± 3 years for new‐onset clinical AF and SCD events (appropriate defibrillation for ventricular tachyarrhythmias, resuscitated cardiac arrest, or SCD). Results: One or more comorbidity was present in 75% of HCM patients, including 50% with ≥2 comorbidities, most commonly obesity (body mass index [BMI] ≥ 30 kg/m2) in 43%. New‐onset atrial fibrillation developed in 11% of our cohort (2.6%/year). On univariate analysis, obesity was associated with a 1.7‐fold increased risk for AF (p =.03) with 12% of obese patients developing AF (3.3%/year) as compared to 7% of patients with BMI < 25 kg/m2 (1.6%/year; p =.006). On multivariate analysis, age and LA transverse dimension emerged as the only variables predictive of AF. Comorbidities, including obesity, were not independently associated with AF development (p >.10 for each). SCD events occurred in 3.3% of patients (0.8%/year) and neither obesity nor other comorbidities were associated with increased risk for SCD (p >.10 for each). Conclusions: In adult HCM patients comorbidities do not appear to impact AF or SCD risk. Therefore, for most patients with HCM, adverse disease related events of AF and SCD appear to be primarily driven by underlying left ventricular and atrial myopathy as opposed to comorbidities. [ABSTRACT FROM AUTHOR]

Background: Charge density mapping of atrial fibrillation (AF) reveals dynamic localized rotational activation (LRA), irregular activation (LIA) and focal firing (FF). Their spatial stability, conduction characteristics and the optimal duration of mapping required to reveal these phenomena and has not been explored. Methods: Bi‐atrial mapping of AF propagation was undertaken using AcQMap (Acutus Medical) and variability of activation patterns quantified up to a duration of 30 s. The frequency of each pattern was quantified at each unique point of the chamber over two separate 30‐s recordings before ablation and R2 calculated to quantify spatial stability. Regions with the highest frequency were identified at increasing time durations and compared to the result over 30 s using Cohen's kappa. Properties of regions with the most stable patterns were assessed during sinus rhythm and extrastimulus pacing. Results: In 21 patients, 62 paired LA and RA maps were obtained. LIA was highly spatially stable with R2 between maps of 0.83 (0.71–0.88) compared to 0.39 (0.24–0.57), and 0.64 (0.54–0.73) for LRA and FF, respectively. LIA was most temporally stable with a kappa of >0.8 reached by 12 s. LRA showed greatest variability with kappa >0.8 only after 22 s. Regions of LIA were of normal voltage amplitude (1.09 mv) but showed increased conduction heterogeneity during extrastimulus pacing (p =.0480). Conclusion: Irregular activation patterns characterized by changing wavefront direction are temporally and spatially stable in contrast with LRA that is transient with least spatial stability. Focal activation appears of intermediate stability. Regions of LIA show increased heterogeneity following extrastimulus pacing and may represent fixed anatomical substrate. [ABSTRACT FROM AUTHOR]

Introduction: Local impedance (LI) drops during radiofrequency ablation can predict lesion formation. Some conduction gaps during pulmonary vein isolation (PVI) can be associated with nonendocardial connections. This study aimed to investigate the incidence, characteristics, and predictors of endocardial and nonendocardial conduction gaps during an LI‐guided PVI. Methods and Results: We prospectively enrolled 157 consecutive patients undergoing an initial LI‐guided extensive PVI of atrial fibrillation (AF). After the first‐pass encirclement, the residual conduction gaps and reconnected gaps were mapped using Rhythmia (Boston Scientific) and a mini‐basket catheter. Right and left PV (RPV/LPV) gaps were observed in 22.3% and 18.5% of the patients, respectively: 27 endocardial and 49 nonendocardial gaps. The carina regions were common sites for the gaps (51 carina‐related vs. 25 noncarina‐related). The carina‐related gaps consisted of more nonendocardial gaps than endocardial gaps (RPVs: 90.0% vs. 10.0%, p =.001; LPVs: 76.2% vs. 23.8%, p <.001). A univariate analysis revealed that paroxysmal AF and the left atrial (LA) volume index for RPV endocardial gaps (odds ratio [OR]: 8.640 and 0.946; p =.043 and 0.009), minor right inferior PV diameter for RPV nonendocardial gaps (OR: 1.165; p =.028), and major left inferior PV diameter for LPV endocardial gaps (OR: 1.233; p =.028) were significant predictors. Conclusions: During the LI‐guided PVI, approximately two‐thirds of the conduction gaps were nonendocardial. The carina regions had more conduction gaps than noncarina regions, which was due to the presence of nonendocardial connections. Paroxysmal AF, a lower LA volume index, and larger inferior PV diameters may increase the risk of conduction gaps. [ABSTRACT FROM AUTHOR]

Introduction: Ultrahigh‐density mapping for ventricular tachycardia (VT) is increasingly used. However, manual annotation of local abnormal ventricular activities (LAVAs) is challenging in this setting. Therefore, we assessed the accuracy of the automatic annotation of LAVAs with the Lumipoint algorithm of the Rhythmia system (Boston Scientific). Methods and Results: One hundred consecutive patients undergoing catheter ablation of scar‐related VT were studied. Areas with LAVAs and ablation sites were manually annotated during the procedure and compared with automatically annotated areas using the Lumipoint features for detecting late potentials (LP), fragmented potentials (FP), and double potentials (DP). The accuracy of each automatic annotation feature was assessed by re‐evaluating local potentials within automatically annotated areas. Automatically annotated areas matched with manually annotated areas in 64 cases (64%), identified an area with LAVAs missed during manual annotation in 15 cases (15%), and did not highlight areas identified with manual annotation in 18 cases (18%). Automatic FP annotation accurately detected LAVAs regardless of the cardiac rhythm or scar location; automatic LP annotation accurately detected LAVAs in sinus rhythm, but was affected by the scar location during ventricular pacing; automatic DP annotation was not affected by the mapping rhythm, but its accuracy was suboptimal when the scar was located on the right ventricle or epicardium. Conclusion: The Lumipoint algorithm was as/more accurate than manual annotation in 79% of patients. FP annotation detected LAVAs most accurately regardless of mapping rhythm and scar location. The accuracy of LP and DP annotations varied depending on mapping rhythm or scar location. [ABSTRACT FROM AUTHOR]

Introduction: The muscular sleeves (or myocardial extensions) derived from the right ventricle infundibulum myocardium are considered the true anatomic substrate for right ventricular outflow tract arrhythmias. Methods: Pulmonary valve specimens obtained from 65 donors (24.6% females, mean age 45.9 ± 15.8 years) were investigated micro‐anatomically. Specimens were histologically processed, stained with Masson's Trichrome, and examined under a light microscope. Results: The myocardial extensions were present in the left anterior pulmonary valve sinus in 86.2% of cases, in the right anterior sinus in 89.2% of cases and in 90.7% of cases in the posterior sinus (p =.699). In 69.2% of examined hearts, the myocardial extensions were present in all sinuses. The mean height of the extensions was 4.12 ± 1.76 (left anterior) versus 3.69 ± 1.47 (right anterior) versus 4.28 ± 1.73 mm (posterior) (p =.137). The myocardial extensions occupied an average of 28.9 ± 10.4% of the left anterior sinus, 26.7 ± 11.2% of the right anterior sinus, and 31.9 ± 11.3% of the posterior sinus (p =.044). Sleeves extending beyond the fibro‐arterial transition zone were present in at least one sinus in 33.8% of hearts (in 7.7% (5/65) of the left and right anterior sinuses and 21.5% (14/65) of posterior sinus, p =.021). Conclusions: The myocardial extensions of the pulmonary valve are common anatomical entities. Although the length of the myocardial sleeves is similar in all pulmonary valve sinuses, their relative extent is greatest in the posterior sinus. Long sleeves that spread beyond the fibro‐arterial transition zone were observed in one‐third of hearts, predominantly in the posterior sinus. Myocardial and fibrous tissue layer thicknesses varied considerably. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation is considered the first‐line treatment of symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). It has been associated with a risk of heart block (HB) requiring a pacemaker. This study aims to determine potential clinical predictors of complete heart block as a result AVNRT ablation. Methods: Consecutive patients undergoing catheter ablation for AVNRT from January 2001 to June 2019 at two tertiary hospitals were included. We defined ablation‐related HB as the unscheduled implantation of pacemaker within a month of the index procedure. Use of electroanatomic mapping (EAM), operator experience, inpatient status, age, sex, fluoroscopy time, baseline PR interval, and baseline HV interval was included in univariate and multivariate models to predict HB post ablation. Results: In 1708 patients (56.4 ± 17.0 years, 61% females), acute procedural success was 97.1%. The overall incidence of HB was 1.3%. Multivariate analysis showed that age more than 70 (odds ratio [OR] 7.907, p ≤.001, confidence interval [CI] 2.759–22.666), baseline PR ≥ 190 ms (OR 2.867, p =.026, CI 1.135–7.239) and no use of EAM (OR 0.306, p =.037, CI 0.101–0.032) were independent predictors of HB. Conclusion: Although the incidence of HB post AVNRT ablation is generally low, patients can be further stratified using three simple predictors. [ABSTRACT FROM AUTHOR]

Background: Inflammation, such as that associated with intermediate CD14++CD16+ monocytes and atrial structural remodeling (SRM), may be important in the recurrence of atrial fibrillation (AF) after catheter ablation. However, the relationship between the intermediate CD14++CD16+ monocytes, SRM, and AF recurrence is unclear. Methods: Twenty‐four patients with AF were enrolled. The proportion of intermediate monocytes (PIM) was assessed before ablation by flow cytometry. As a surrogate marker of SRM, the volume ratio (VR) of signal intensity greater than 1 standard deviation on late‐gadolinium enhancement magnetic resonance imaging (LGE‐MRI) was calculated. We investigated whether PIM correlated with SRM on LGE‐MRI and determined the optimal cutoff value for predicting AF recurrence. Results: Univariate analysis revealed positive correlations between PIM and BNP with SRM (PIM: r =.593, p =.002; BNP: r =.567, p =.004). Multivariable analysis revealed that PIM was independently associated with VR on LGE‐MRI (β =.522; p =.033). The finding of an area under the receiver operating characteristic curve of 0.750 revealed that a VR ≥ 13.3% on LGE‐MRI as the optimal cutoff value to predict AF recurrence with 80% sensitivity and 71% specificity, which was associated with PIM ≥ 10.0%. Conclusion: Intermediate monocytes were significantly positively correlated with SRM. PIM ≥ 10% was associated with a VR ≥ 13.3% on LGE‐MRI, which predicted AF recurrence after catheter ablation. [ABSTRACT FROM AUTHOR]

Introduction: Left atrial posterior wall (LAPW) isolation may be performed as an additional atrial fibrillation (AF) ablation strategy based on pulmonary vein isolation. A modified posterior‐inferior line (MPL) was proposed for reducing esophageal injury. The aim of this study was to evaluate the anatomical characteristics of the MPL, compared with the conventional posterior line (CPL). Methods and Results: Multidetector computed tomography was performed in 102 consecutive AF patients (male/female = 60/42) preoperative, and the parameters were evaluated as follows: the distance from MPL and CPL to the esophagus, fat pad presence and thickness in the course of MPL and CPL, and the esophageal route below CPL. The average distance from the MPL to the esophagus was longer than from CPL to the esophagus (3.7 ± 1.5 vs. 1.7 ± 0.4 mm, p <.001). Proportion of fat pad was higher in the course of MPL than CPL. The myocardium tissue and fat pad under MPL was thicker than under CPL (2.9 ± 1.1 vs. 1.6 ± 0.3 mm, p <.001; 1.4 ± 0.6 vs. 0.9 ± 0.2 mm, p <.001), respectively. In patients whose esophagus was unconfined in a triangular space at the left inferior pulmonary vein level, the average distance from MPL to esophagus was longer than the confined patients (4.0 ± 1.7 vs. 3.2 ± 1.0 mm, p =.001). Conclusion: The MPL was far away from the esophagus with thicker myocardium tissue and more fat pad than the CPL; thus, MPL could serve as a favorable alternative in linear ablation for LAPW isolation. [ABSTRACT FROM AUTHOR]

Background: Current guidelines recommend defibrillation testing (DT) performance in patients with a subcutaneous implantable cardioverter defibrillator (S‐ICD), theoretically to reduce the amount of ineffective shocks. DT, however, has been proven unnecessary in transvenous ICD and real‐world data show a growing trend in avoidance of DT after S‐ICD implantation. Methods: All patients undergoing S‐ICD implant at nine associated Italian centers joining in the ELISIR registry (ClinicalTrials.gov Identifier: NCT04373876) were enrolled and classified upon DT performance. Long‐term follow‐up events were recorded and compared to report the long‐term efficacy and safety of S‐ICD implantations without DT in a real‐world setting. Results: A total of 420 patients (54.0 ± 15.5 years, 80.0% male) were enrolled in the study. A DT was performed in 254 (60.5%) patients (DT+ group), while in 166 (39.5%) was avoided (DT− group). Over a median follow‐up of 19 (11–31) months, a very low rate (0.7%) of ineffective shocks was observed, and no significant differences in the primary combined arrhythmic outcome were observed between the two groups (p =.656). At regression analysis, the only clinical predictor associated with the primary combined outcome was S‐ICD placement for primary prevention (odds ratio: 0.42; p =.013); DT performance instead was not associated with a reduction in primary outcome (p =.375). Conclusion: Implanting an S‐ICD without DT does not appear to impact the safety of defibrillation therapy and overall patients' survival. [ABSTRACT FROM AUTHOR]

Introduction: Elevated left atrial pressure (LAP) during catheter ablation of atrial fibrillation (AF) is associated with an increased risk of AF recurrence, but it is unknown if this correlates with heart failure (HF). The objective of the study was to determine if elevated LAP after AF ablation correlates with HF events. Methods: Prospective, single‐center, cohort study measuring LAP and right atrial pressure (RAP) during AF ablation in 100 patients. The primary endpoint was clinical HF within 30 days of ablation. The secondary outcome was AF‐free HF. Results: One hundred patients (63% male, mean age 64.5) were enrolled and 20% had clinical HF within 30 days. Bivariate correlates included mitral valve (MV) disease, persistent AF, class III antiarrhythmics, LAP, and recurrent AF. Multivariate analysis revealed class III antiarrhythmics were protective (odds ratio [OR]: 0.24 [0.1–0.5], p =.04), while MV disease (OR: 8.7 [3.3–23], p =.03) and loop diuretics (OR: 4.8 [2.6–9.1], p =.01) were hazardous. AF‐free HF occurred in 9% of patients and correlated with higher LAP and RAP, and chronic kidney disease. Conclusion: Patients with HF after AF ablation had higher LAP. MV disease, diuretic use, and class III antiarrhythmics also correlated to HF. These present opportunities to target future interventions to reduce a common complication of AF ablation. [ABSTRACT FROM AUTHOR]

Introduction: Cardiac sympathetic denervation (CSD) is utilized for the management of ventricular tachycardia (VT) in structural heart disease when refractory to radiofrequency ablation (RFA) or when patient/VT characteristics are not conducive to RFA. Methods: We studied consecutive patients who underwent CSD at our institution from 2009 to 2018 with VT requiring repeat RFA post‐CSD. Patient demographics, VT/procedural characteristics, and outcomes were assessed. Results: Ninety‐six patients had CSD, 16 patients underwent RFA for VT post‐CSD. There were 15 male and 1 female patients with mean age of 54.2 ± 13.2 years. Fourteen patients had nonischemic cardiomyopathy. A mean of 2.0 ± 0.8 RFAs for VT was unsuccessful before the patient undergoing CSD. The median time between CSD and RFA was 104 days (interquartile range [IQR] = 15–241). The clinical VT cycle length was significantly increased after CSD both spontaneously on ECG and/or ICD interrogation (355 ± 73 ms pre‐CSD vs. 422 ± 94 ms post‐CSD, p =.001) and intraprocedurally (406 ± 86 ms pre‐CSD vs. 457 ± 88 ms post‐CSD, p =.03). Two patients had polymorphic and 14 had monomorphic VT (MMVT) pre‐CSD, and all patients had MMVT post‐CSD. The proportion of mappable, hemodynamically stable VTs increased from 35% during pre‐CSD RFA to 58% during post‐CSD RFA (p =.038). At median follow‐up of 413 days (IQR = 43–1840) after RFA, eight patients had no further VT. Conclusion: RFA for recurrent MMVT post‐CSD is a reasonable treatment option with intermediate‐term clinical success in 50% of patients. Clinical VT cycle length was significantly increased after CSD with associated improvement in mappable, hemodynamically tolerated VT during RFA. [ABSTRACT FROM AUTHOR]

The article focuses on incidence and determinants of QT interval prolongation in COVID-19 patients has treated with hydroxychloroquine and azithromycin. Topics inlcude the combined use of hydroxychloroquine and azithromycin being globally has adopted, in part due to paucity and high cost of alternative therapies, and the utility of these medications has been questioned and thus safety becomes a major concern given clinical equipoise regarding efficacy.

Introduction: Intramural scarring is a risk factor for sudden cardiac death. The objective of this study was to determine the value of scar quantification for risk stratification in patients with nonischemic cardiomyopathy (NICM) undergoing ablation procedures for ventricular arrhythmias (VA). Methods and Results: Cardiac late gadolinium‐enhanced magnetic resonance imaging was performed in patients with NICM referred for ablation of premature ventricular complexes or ventricular tachycardia (VT). Only patients with intramural delayed enhancement were included. Scar volume was measured and correlated with immediate and long‐term outcomes. Receiver operator curves, Wilcoxon signed‐rank testing, and logistic regression were used to compare patient characteristics. The study consisted of 99 patients (74 males, mean age: 59.6 [54.0‐68.1] years, ejection fraction [EF]: 46.0 [35.0‐60.0]%). Patients without clinical VT or inducible VT had smaller total and core scar size compared to patients with a history of VT or inducible VT (total scar 1.12 [0.74‐1.79] cm3 vs 7.45 [4.16‐12.21] cm3, P <.001). A total scar volume of greater than or equal to 2.78 cm3 was associated with inducibility of VT (AUC 0.94, 95% CI [0.89‐0.98], sensitivity 85%, specificity 90%). Scar volume was associated with VT inducibility independent of a prior history of VT or the preprocedure EF (adjusted OR 1.67 [1.24‐2.24]/cm3, P <.01). Conclusion: Quantification of scar size in patients with intramural scarring is useful for risk stratification in patients with NICM and VA independent of the EF or a prior history of VT. Scar characteristics of patients without a history of VT who have inducible VT are similar to patients with a history of VT. [ABSTRACT FROM AUTHOR]

Introduction: Stochastic trajectory analysis of ranked signals (STAR) mapping has recently been used to ablate persistent atrial fibrillation (AF) with high rates of AF termination and long‐term freedom from AF in small, single‐arm studies. We hypothesized that rapidity and organization markers would correlate with early sites of activation (ESA). Methods: Patients undergoing persistent AF ablation as part of the STAR mapping study were included. Five‐minute unipolar basket recordings used to create STAR maps were used to determine the minimum‐cycle length (Min‐CL) and CL variability (CLV) at each electrode to identify the site of the fastest Min‐CL and lowest CLV across the left atrium (LA). The location of ESA targeted with ablation was compared with these sites. Dominant frequency was assessed at ESA and compared with that of neighboring electrodes to assess for regional gradients. Results: Thirty‐two patients were included with 83 ESA ablated, with an ablation response at 73 sites (24 AF termination and 49 CL slowing ≥30 ms). Out of these, 54 (74.0%) and 56 (76.7%) colocated to sites of fastest Min‐CL and lowest CLV, respectively. Regional CL and frequency gradients were demonstrable at majority of ESA. ESA colocating to sites of fastest Min‐CL and lowest CLV were more likely to terminate AF with ablation (odds ratio, 34 and 29, respectively, P =.02). These showed a moderate sensitivity (74.0% Min‐CL and 75.3% CLV) and specificity (66.7% Min‐CL and 76.9% CLV) in predicting ESA with an ablation response. Conclusions: ESA correlate with rapidity and organization markers. Further work is needed to clarify any role for spectral analysis in prioritizing driver ablation. [ABSTRACT FROM AUTHOR]

Introduction: The phase 3 EURIDIS and ADONIS studies evaluated dronedarone for atrial fibrillation (AF)/atrial flutter (AFL) recurrence in patients with nonpermanent AF. Here we assessed whether patient characteristics and/or treatment outcomes in these studies differed based on the need for cardioversion before randomization. Methods: Time to adjudicated first AF/AFL recurrence, symptomatic recurrence, cardiovascular hospitalization/death, and AF hospitalization, and safety were assessed by cardioversion status. Results: Of 1237 patients randomized (2:1 dronedarone:placebo), 364 required baseline cardioversion (dronedarone 243, placebo 121). Patients requiring cardioversion had a greater prevalence of cardiovascular comorbidities and shorter times to first AF/AFL recurrence compared with those not requiring cardioversion. Dronedarone was associated with longer median time to first AF/AFL recurrence vs placebo regardless of cardioversion status (cardioversion: 50 vs 15 days, hazard ratio [HR] 0.76; 95% confidence interval [CI], 0.59‐0.97; P =.02; non‐cardioversion: 150 vs 77 days, HR 0.76; 95% CI, 0.64‐0.90; P <.01). Dronedarone was similarly associated with prolonged median time to symptomatic recurrence vs placebo in the cardioversion (347 vs 87 days, HR 0.65; 95% CI, 0.49‐0.87) and non‐cardioversion (288 vs 120 days, HR 0.74; 95% CI, 0.62‐0.90) populations. Risk of cardiovascular hospitalization/death and first AF hospitalization was lower with dronedarone vs placebo regardless of cardioversion status, but differences were not statistically significant. The safety of dronedarone was similar in both groups. Conclusion: Patients requiring baseline cardioversion represent a distinct population, having more underlying cardiovascular disease and experiencing a shorter time to AF/AFL recurrences. Dronedarone was associated with improved efficacy vs placebo regardless of cardioversion status. [ABSTRACT FROM AUTHOR]

Background: Left atrial substrate modification targeting low voltage zones (LVZ) is an ablation strategy that—in addition to pulmonary vein (PV) isolation—tries to eliminate arrhythmogenic mechanisms harbored in such tissue. Electrophysiological findings at reablation include (a) PV reconnection, (b) reconnection over previous substrate ablation, and (c) de‐novo LVZ. Objective: To study, prevalence and contribution of these arrhythmogenic electrophysiological entities in patients with atrial fibrillation (AF) recurrences. Methods: Consecutive patients with highly symptomatic AF undergoing index and reablation were included (n = 113). In all patients' PV reconnection, reconnection over previous substrate ablation and spontaneous de‐novo LVZ were quantitatively assessed and integrated into an individual reablation strategy. Follow‐up was based on continuous device monitoring. Results: At re‐do procedure, 45 out of 113 (39.8%) patients showed PV reconnection as the only electrophysiological abnormality. Reconduction over previous lines was the only electrophysiological abnormality in 8 out of 113 (7.1%) patients. Spontaneous de‐novo LVZ was the only electrophysiological abnormality in 12 out of 113 (10.6%) patients. Combined findings of PV reconnection, line reconduction, and/or spontaneous de‐novo LVZ were seen in 40 out of 113 (35.4%) patients. No detectable electrophysiological abnormality was observed in 8 out of 113 (7.1%) patients. In univariate analysis, none of the tested electrophysiological characteristics independently predicted the outcome after re‐do. Conclusions: In patients undergoing reablation, we could show that reconduction over previous substrate ablation as well as the development of new low voltage areas are frequent findings besides classical PV reconnection—without a clear leading cause for recurrences. These findings impact reablation strategies as well as the strategic focus during index procedures. [ABSTRACT FROM AUTHOR]