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Introduction Methods and Results Conclusions Long QT syndrome (LQTS) is a cardiac channelopathy characterized by QT prolongation and a potential for arrhythmic syncope, sudden cardiac arrest or deaths (SCA/SCD). It has been speculated that patients with LQTS might have a primary sinoatrial node (SAN) phenotype of chronotropic insufficiency (CI). This has not been demonstrated convincingly before because of the potentially confounding effects of beta blocker (BB) therapy. Herein, we set out to determine whether untreated patients with LQTS demonstrate intrinsic CI.A retrospective review of all treadmill exercise stress tests (TEST) was performed on patients with one of the three most common LQTS genotypes: LQT1, LQT2, and LQT3. For each patient, the first TEST completed while off BB was analyzed. Patients with prior left cardiac sympathetic denervation (LCSD) therapy were excluded. CI was defined as having an age‐ and gender‐predicted peak heart rate (HR) < 85% and/or a predicted HR reserve (HRR) < 80%. Overall, 463 LQTS patients (245 LQT1, 125 LQT2, and 93 LQT3) were included (267 female [58%]; mean age at time of TEST [29 ± 17 years]). Mean % predicted peak HR for all LQTS patients was 87.6% (range 42.9% ‐ 119.1%) and mean % predicted HRR was 80% (range 19.1% ‐ 153%). Overall, half of all LQTS patients (n = 234; 51%) displayed CI; 64% of patients with LQT1 (n = 157), 37% with LQT2 (n = 46), and 33% with LQT3 (n = 31). Patients with LQT1 were most likely to exhibit CI compared to patients with LQT2 (p < .0001) and LQT3 (p < .0001). CI was significantly more common in LQT1 compared to controls (p < .0001), while there was no difference between LQT2 (p = .5) or LQT3 and controls (p > .9). Presence of CI was not a predictor of LQTS‐associated symptoms, BB side effects or likelihood of future breakthrough cardiac events (BCE).Patients with LQTS, particularly LQT1, demonstrate a SAN phenotype of CI. If assessing BB therapy effect by impact on peak HR, the patient's pretreatment peak HR, rather than an age‐ and gender‐predicted maximum HR, should be used. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusions Carotid sinus syndrome (CSS), characterized by exaggerated vagal responses leading to asystolic pauses with carotid sinus massage (CSM), often necessitates pacemaker implantation. This study investigates cardioneuroablation (CNA) as an alternative strategy for CSS.Prospective study of consecutive patients referred for CNA due to CSS. All patients underwent CSM, atropine test and 24‐h Holter monitoring before the procedure and at 6 months. The primary objective was the absence of any cardioinhibitory response to CSM following CNA. Secondary objectives included the combined endpoint of syncope and presyncope‐free survival, pacemaker‐free survival, differences in heart rate variation (HRV), as well as differences in the pre‐ and postprocedure atropine tests and in the SF‐36 quality‐of‐life questionnaire.A total of 13 consecutive patients (84.6% male, mean age 63.8 ± 12.3 years) were included. CSM revealed a symptomatic asystolic pause in all patients before CNA (7.3 [5.6–10.5] s). After the procedure, all the patients had a negative CSM, and only one patient (7.7%) had a positive CSM at 6 months. After a median follow‐up of 11.2 (10.6–16.3) months, syncope or presyncope‐free survival was 84.6%, and none required pacemaker implantation. There was an improvement in the energy and health change items in the SF‐36 questionnaire. There was a reduction in HR increase in the atropine test at 6 months (pre‐CNA: 66% [52–84] vs. post‐CNA 26.0% (19.8–29.3]; p = .008) and in HRV parameters.In this proof‐of‐efficacy study, performed in patients affected by asystolic CSS, CNA was effective in reducing the rate of cardioinhibitory responses, suggesting a potential efficacy in also reducing syncopal recurrences. Controlled trials are warranted to corroborate clinical findings. [ABSTRACT FROM AUTHOR]

Introduction: Thermal atrial fibrillation (AF) ablation exerts an additive treatment effect on the cardiac autonomic nervous system (CANS). This effect is mainly reported during ablation of the right superior pulmonary vein (RSPV), modulating the right anterior ganglionated plexus (RAGP), which contains parasympathetic innervation to the sinoatrial node in the epicardial fat pad between RSPV and superior vena cava (SVC). However, a variable response to neuromodulation after ablation is observed, with little to no effect in some patients. Our objective was to assess clinical and anatomic predictors of thermal ablation‐induced CANS changes, as assessed via variations in heart rate (HR) postablation. Methods: Consecutive paroxysmal AF patients undergoing first‐time PV isolation by the cryoballoon (CB) or radiofrequency balloon (RFB) within a 12‐month time frame and with preprocedural cardiac computed tomography (CT), were evaluated. Preablation and 24‐h postablation electrocardiograms in sinus rhythm were collected and analyzed to assess HR. Anatomic evaluation by CT included the measurement of the shortest distance between the SVC and RSPV ostium (RSPV‐SVC distance). Results: A total of 97 patients (CB, n = 50 vs. RFB, n = 47) were included, with similar baseline characteristics between both groups. A significant HR increase postablation (ΔHR ≥ 15 bpm) occurred in a total of 37 patients (38.1%), without difference in number of patients between both thermal ablation technologies (CB, 19 [51%]), RFB, 18 [49%]). Independent predictors for increased HR were RSPV‐SVC distance (odds ratio [OR]: 0.49, CI: 0.34–0.71, p value <.001), and age (OR: 0.94, CI: 0.89–0.98, p value =.003). Conclusions: Thermal balloon‐based PV isolation influences the CANS through its effect on the RAGP, especially in younger patients and patients with shorter RSPV‐SVC distance. [ABSTRACT FROM AUTHOR]

Introduction: Early‐onset atrial fibrillation (AF) has already been observed in approximately 2% of patients with genetically proven long QT syndrome (LQTS). This frequency is higher than population‐based estimates of early‐onset AF. However, the concomitant expression of AF in LQTS is likely underestimated. The purpose of this study was to examine the clinical presentation, genetic background, and outcomes of a cohort of patients with LQTS and early‐onset AF referred to a single tertiary center. Methods: Twenty‐seven patients diagnosed with congenital LQTS were included in the study based on the documentation of early‐onset (age ≤50 years) clinical or subclinical AF episodes in all available medical records, including standard electrocardiograms, wearable monitor or cardiac implantable electronic devices. Results: Seventeen patients experienced clinical AF during the follow‐up period. Subclinical AF was detected in 10 patients through insertable or wearable cardiac monitors. In our series, the mean heart rate during AF episodes was found to be relatively low despite the patients' young age and the low or minimal effective doses of beta‐blockers used for QTc interval control. All patients exhibiting LQTS and early‐onset AF were genotype positive, carrying mutations in the KCNQ1 (66%), KCNH2, KCNE1, and SCN5A genes. Notably, most of these patients carried the same p.(R231C) mutation in the KCNQ1 gene (59%) and were from the same families, suggesting concurrent expression of familial AF and LQTS. Conclusion: LQTS patients are prone to developing clinical and subclinical AF, even at a younger age. The occurrence of early‐onset AF in the LQTS population could be more frequent than previously assumed. AF should be considered as a potential dysrhythmia related to LQTS. Our study emphasizes the importance of carefully researching clinical and/or subclinical episodes of AF through strict heart rhythm monitoring in the LQTS population. [ABSTRACT FROM AUTHOR]

Introduction: Implantable permanent pacemaker function is supported by their energy sources for a mean period of 8.8–12.4 years. We previously published this case of a patient with a normally functioning VVI pacemaker, 31 years after implantation. Methods and Results: In this report, we state that the device is still functioning normally 40 years after implantation. The most recent device interrogation revealed pacing threshold of 0.9 V/0.5 ms. Holter monitoring for 24 hours recorded a total of 98.707 beats with 97.78% paced beats, without any indication of pacemaker malfunction and with stable heart rate at 70–71 bpm. Conclusion: Most patients with implantable devices have the appropriate follow‐up and settings of low energy consumption. Manufacturing companies should focus on prolonging device longevity, to produce future devices with higher energy capacity. [ABSTRACT FROM AUTHOR]

Introduction: This study sought to elucidate the impact of vein of Marshall (VOM) chemical ablation on atrial fibrillation (AF) drivers by investigating the changes in CARTOFINDER mappings before and after VOM chemical ablation in patients with persistent AF. Methods: This study included 23 consecutive patients undergoing catheter ablation for long‐persistent AF (>18 months). VOM chemical ablation was performed following pulmonary vein isolation. CARTOFINDER and AF cycle length (AFCL) maps were created in the left atrium (LA) before and after VOM chemical ablation. The LA was divided into 8 segments, and the number of focal activation points with 6 or more repetitions was counted in each segment. Results: The number of focal activation points was largest in the LA appendage (LAA). After VOM chemical ablation, the number of focal activation points in the LA decreased significantly (37 [interquartile range, IQR: 19–55] vs. 15 [IQR: 7–21], p <.001), and median AFCL was significantly prolonged (159 [147–168] vs. 164 [150–173] ms, p <.001). In the assessment of each segment, significant decreases in focal activation points were observed in the inferior, lateral, and anterior segments and LAA. Among the focal activation points disappearing after chemical ablation, the number in the non‐ethanol‐affected area was significantly larger than that in the affected area (13 [8–25] vs. 4 [1–10], p <.001). Conclusions: VOM chemical ablation decreases AF drivers detected by CARTOFINDER. Mechanisms other than direct myocardial damage are considered to contribute the attenuation of AF drivers. [ABSTRACT FROM AUTHOR]

Introduction: The accuracy of surface ECG algorithms for predicting the origin of outflow tract ventricular arrhythmias (OT‐VAs) might be questioned. Intracardiac electrograms recorded at anatomic landmarks could provide new predictive insights. We aim to evaluate the efficacy of a novel criterion utilizing the activation pattern of the coronary sinus (CS) in localizing OT‐VAs, including VAs originating from the right ventricular outflow tract (RVOT), endocardial left ventricular outflow tract (Endo‐LVOT), and epicardial left ventricular outflow tract (Epi‐LVOT). Methods: We measured the ventricular activation time of the mitral annulus (MA) from the onset of the earliest QRS complex of VAs to the initial deflection over the isoelectric line at local signals, namely the QRS‐MA interval. The activation at 3 and 12 o'clock of the MA was recorded as the QRS‐MA3 and QRS‐MA12 intervals, respectively. Their predictive values were compared to previous ECG algorithms. Results: A total of 68 patients with OT‐VAs were enrolled (51 for development and 17 for validation). From early to late, the ventricular activation sequences at MA12 were as follows: Epi‐LVOT, Endo‐LVOT, and RVOT. In LBBB morphology OT‐VAs, the QRS‐MA12 interval was significantly earlier for LVOT origins than RVOT origins. In the combined cohort of development and validation cohort, a cut‐off value of ≤10 ms predicted the LVOT origin with a sensitivity of 100% and specificity of 78%. The QRS‐MA12 interval ≤ −24 ms additionally predicted epicardial LVOT sites of origin. Conclusions: The QRS‐MA interval could accurately differentiate the OT‐VAs localization. [ABSTRACT FROM AUTHOR]

Introduction: Ablation of scar‐related reentrant atrial tachycardia (SRRAT) involves identification and ablation of a critical isthmus. A graph convolutional network (GCN) is a machine learning structure that is well‐suited to analyze the irregularly‐structured data obtained in mapping procedures and may be used to identify potential isthmuses. Methods: Electroanatomic maps from 29 SRRATs were collected, and custom electrogram features assessing key tissue and wavefront properties were calculated for each point. Isthmuses were labeled off‐line. Training data was used to determine the optimal GCN parameters and train the final model. Putative isthmus points were predicted in the training and test populations and grouped into proposed isthmus areas based on density and distance thresholds. The primary outcome was the distance between the centroids of the true and closest proposed isthmus areas. Results: A total of 193 821 points were collected. Thirty isthmuses were detected in 29 tachycardias among 25 patients (median age 65.0, 5 women). The median (IQR) distance between true and the closest proposed isthmus area centroids was 8.2 (3.5, 14.4) mm in the training and 7.3 (2.8, 16.1) mm in the test group. The mean overlap in areas, measured by the Dice coefficient, was 11.5 ± 3.2% in the training group and 13.9 ± 4.6% in the test group. Conclusion: A GCN can be trained to identify isthmus areas in SRRATs and may help identify critical ablation targets. [ABSTRACT FROM AUTHOR]

Introduction: According to current guidelines, pulmonary vein isolation as first‐line therapy should be considered for patients with atrial fibrillation (AF), however, optimal timing of the procedure is still unknown in patients with heart failure (HF). We aimed to evaluate the effect of early catheter ablation (CA) in patients with HF and left ventricular ejection fraction (LVEF) below 50%. Methods: We analyzed data from a structured registry comprising 227 patients with paroxysmal or persistent AF and HF with LVEF < 50% who underwent radiofrequency CA between 2015 and 2022. Early CA was defined as a procedure performed within 12 months of AF diagnosis. The median follow‐up duration was 1748 (1176.3–2353.5) days, with a minimum follow‐up of 365 days. Our endpoints were AF recurrence after a 3‐months blanking period and all‐cause mortality. Results: Among the 227 patients with a median age of 64.3 years, 97 (42.7%) experienced AF recurrence and 55 (24.2%) died during the follow‐up period. The median LVEF was 40% for early CA and 38% for delayed CA (p =.053). Early CA significantly reduced AF recurrence (HR = 0.25 [0.15–0.42], p <.001), however, the timing of procedure did not affect all‐cause mortality (p =.16). These findings were consistent regardless of AF subtype or the burden of comorbidities, as assessed by the CHA2DS2‐VASc score. Conclusion: The timing of CA of AF appears to be an important factor in patients with HF. Early CA reduced AF recurrence, although it does not impact all‐cause mortality. We found similar results regardless of AF subtype or burden of comorbidities. [ABSTRACT FROM AUTHOR]

Introduction: Inappropriate sinus tachycardia (IST) is a common condition with frequently not tolerated beta‐blockers or ivabradine and a high rate of complication in ablation strategy; we describe an alternative anatomical approach of sinus node (SN) modulation. Methods: This retrospective study describes a case series of 6 patients from two centers diagnosed with symptomatic IST undergoing SN ablation. Results: The mean age was 40.6 ± 13.9 years; five of the six patients were female, 100% of patients reported heart palpitations, and 66% reported dizziness, the average heart rate (HR) on a 24‐h Holter was 93.2 ± 7.9 bpm. HR during the first stage of a stress test using a standard Bruce protocol was 150 ± 70 bpm, The average HR on 24‐h Holter postablation was 75 ± 5.6 bpm, the sinus rate HR during stage 1 of a Bruce protocol exercise stress test was 120 ± 10 bpm. Conclusion: This is the first case series reporting the acute and long‐term results of a novel anatomical approach for SN modulation to treat IST targeting the arcuate ridge (AR) under intracardiac echography (ICE) guidance. The novel anatomic ICE‐guided catheter ablation approach aimed to identify the earliest activation at the AR with an extension of RF lesions toward its septal region seems effective and safe to modulate the SN in symptomatic patients with IST refractory to medical treatment. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 69-year-old female who underwent an electrophysiological study due to recurrent supraventricular tachycardia (SVT). It highlighted the occurrence of a wide complex tachycardia (WCT) and explored the mechanism behind its transformation following a premature ventricular complex (PVC). Treatment discussed involved radiofrequency ablation targeting the base of the triangle of Koch, which successfully eliminated SVT inducibility and potentially the NFV pathway.

Background: Severe first‐degree atrioventricular (AV) block may produce symptoms similar to heart failure due to AV dyssynchrony, a syndrome termed AV dromotropathy. According to guidelines, it should be considered for permanent pacemaker implantation, yet evidence supporting this treatment is scarce. Objectives: This study aimed to determine the impact of AV‐optimized conduction system pacing (CSP) in patients with symptomatic severe first‐degree AV block and echocardiographic signs of AV dyssynchrony. Methods: Patients with symptomatic first‐degree AV block (PR > 250 ms), preserved left ventricular ejection fraction, narrow QRS, and AV dyssynchrony were included in the study. In a single‐blind cross‐over design, patients were randomized to AV sequential CSP or backup VVI pacing with a base rate of 40 bpm. We compared exercise capacity, echocardiographic parameters, and symptom occurrence at the end of 3 months of each period. Results: Fourteen patients completed the study. During the AV‐optimized CSP compared to the backup pacing period, patients achieved a higher workload on exercise test (147.2 ± 50.9 vs. 140.7 ± 55.8 W; p =.032), with a trend towards higher peak VO2 (23.3 ± 7.1 vs. 22.8 ± 7.1 mL/min/kg; p =.224), and higher left ventricular stroke volume (LVSV 74.5 ± 13.8 vs. 66.4 ± 12.5 mL; p <.001). Symptomatic improvement was recorded, with fewer patients reporting general tiredness and 71% of patients preferring the AV‐optimized CSP (p =.008). Conclusions: AV‐optimized CSP could improve symptoms, exercise capacity and LVSV in patients with severe first‐degree AV block. [ABSTRACT FROM AUTHOR]

Introduction Methods and Results Conclusion Pacemaker‐mediated tachycardia is a known arrhythmia in patients with dual chamber pacemakers and defibrillators and intact ventriculoatrial (VA) conduction. We report a case of pacemaker‐mediated reentrant arrhythmia (PMRA) in a patient with an atrioventricular (AV) synchronous leadless pacemaker.A 91‐year‐old female presented with 2:1 AV conduction and received an AV synchronous leadless pacemaker. She had atrial mechanical sense‐ventricular paced beats between heart rates of 80–100 bpm more than 80% of the time. She was found to have a new cardiomyopathy and was referred for placement of biventricular pacemaker. At the time of device implantation, her electrocardiogram showed ventricular pacing with a short RP interval and superiorly directed P waves. Changes in the ventricular pacing rate resulted in changes in the atrial rate. Following device placement, her heart rate decreased to the lower rate limit of her pacemaker. The atrial mechanical sense impulse most likely was generated by a retrograde conducted P wave resulting in near incessant PMRA.PMRA may occur in patients who receive an AV synchronous leadless pacemaker with intact VA conduction and sinoatrial node dysfunction. Due to the lower rates of PMRA, this arrhythmia may be underrecognized. Interventions for and implications of PMRA need further investigation. [ABSTRACT FROM AUTHOR]

Introduction: The presence of low‐voltage zones (LVZs) in the left atrium (LA) is associated with the recurrence of atrial fibrillation (AF) following pulmonary vein isolation (PVI). However, there is variability and conflict in the data regarding predictors of LVZs as reported in previous studies. The objective of this study was to identify predictors for the presence of LVZs in a cohort of patients with persistent AF. Methods: The study prospectively enrolled 439 patients with persistent AF who were scheduled for ablation. Voltage map of the LA was collected using a multipolar catheter. An LVZ was defined as an area of ≥3 cm2 exhibiting a peak‐to‐peak bipolar voltage of <0.5 mV. Results: The mean age of the cohort was 65.3 ± 8.6 years and 26.4% were female. Additionally, 25.7% had significant LVZs, most frequently located in the anterior wall of the LA. Multivariable analysis identified the following independent predictors for LVZ: advanced age (OR [odds ratio] = 1.08, 95% CI [confidence interval] = 1.03–1.13, p =.002); female sex (OR = 4.83, 95% CI = 2.66–8.76, p <.001); coronary artery disease (CAD) (OR = 3.20, 95% CI = 1.32–7.77, p =.01) and enlarged LA diameter (OR = 1.10, 95% CI = 1.04–1.17, p =.001). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the final model was 0.829. Conclusion: Approximately 25% of the patients with persistent AF had LVZs. Advanced age, female sex, CAD, and a larger LA were independent predictors for LVZs with the model demonstrating a very good AUC for the ROC curve. These findings hold the potential to be used to tailor the ablation procedure for the individual patient. [ABSTRACT FROM AUTHOR]

Introduction: Catheter ablation of ectopy originating from the vicinity of the His bundle can be challenging. Methods and Results: We report a case of a 33‐year‐old man with narrow QRS ectopy with preferential conduction from a para‐Hisian origin to the proximal left fascicles, which was successfully eliminated by radiofrequency ablation in the right coronary cusp, guided by ultrahigh‐resolution mapping of the His bundle, bundle branch, and fascicular electrograms. Conclusion: Some narrow QRS ectopy may originate from the vicinity of the conduction system, instead of the "true" conduction system, and have concealed connections from its origin to the conduction system. [ABSTRACT FROM AUTHOR]

Introduction: Postoperative atrial fibrillation (POAF) is common following open heart surgery, and is associated with significant morbidity. Medications used for ventricular rate control of POAF may not be effective in controlling rapid ventricular rates during the postoperative period because of increased sympathetic tone. The purpose of this study was to develop nonpharmacologic rate control of POAF by atrioventricular node (AVN) fat pad stimulation using clinically available temporary pacing wires in the canine sterile pericarditis model. Methods: We studied 10 sterile pericarditis dogs in the closed‐chest state on postoperative days 1−3. The AVN fat pad stimulation (amplitude 2–15 mA; frequency 20 Hz; pulse width 0.03–0.2 ms) was performed during sustained POAF (>5 min). We measured ventricular rate and inefficient ventricular contractions during sustained POAF and compared it with and without AVN fat pad stimulation. Also, the parameters of AVN fat pad stimulation to achieve a rate control of POAF were measured over the postoperative days. Results: Eleven episodes of sustained POAF were induced in 5/10 sterile pericarditis dogs in the closed‐chest state on postoperative days 1−2. During POAF, the AVN fat pad stimulation decreased the ventricular rate from 178 ± 52 bpm to 100 ± 8 bpm in nine episodes. Nonpharmacologic rate control therapy successfully controlled the ventricular rate and eliminated inefficient ventricular contractions during POAF for the duration of the AVN fat pad stimulation. The AVN fat pad stimulation output remained relatively stable over the postoperative days. Conclusion: During sustained POAF, nonpharmacologic rate control by AVN fat pad stimulation effectively and safely controlled rapid ventricular rates throughout the postoperative period. [ABSTRACT FROM AUTHOR]

Introduction: The relationships between baseline tissue local impedance (LI), contact force (CF), atrial fibrosis, and atrial rhythm are uninvestigated in a clinical setting. We compared the relationship of LI and CF between atrial fibrillation (AF) and sinus rhythm (SR) accounting for the effects of atrial fibrosis as assessed by bipolar voltage and LI. Methods: Patients undergoing persistent AF ablation were recruited. LI was recorded referenced to patient blood pool (LIr) and concurrent to changes in CF, with data collected at the same locations in AF and SR. Results: Twenty patients were recruited. 109 locations were sampled obtaining 1903 data points (SR: 966, AF: 937). CF correlated strongly with LI (repeated measures correlation = 0.64). The relationship between CF and LIr was logarithmic. Rhythm and CF had a significant main (both p <.0005) and interaction effect (p =.022) on tissue LI: AF demonstrated higher LIr values than SR for similar CF. Bipolar voltage had no effect on the relationship of CF to LIr in either rhythm. Assessing fibrosis using LIr showed an interaction effect with CF for LIr in SR and AF, (SR: p <.0005, AF: p =.01), with increased fibrosis showing lesser change in LIr per gram of CF. Conclusions: CF and rhythm significantly affect the measured LIr of LA myocardium. Optimal catheter‐tissue coupling may be better achieved with higher levels of CF and in AF rather than SR. Atrial fibrosis, as assessed by LIr but not bipolar voltage, affected the CF–LI relationship. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 62-year-old female patient with irregular tachycardia. Topics discussed include the differential diagnoses of narrow QRS tachycardias such as atrial flutter and orthodromic reciprocating tachycardia, the results of the 12-lead electrocardiogram administered to the patient, and the clinical implications of regularly irregular tachycardia.

Introduction: Cather ablation (CA) is a well‐recognized treatment alternative for atrial fibrillation (AF) patients despite more than 20% ablation‐treated patients suffering from AF recurrence. The underlying mechanism of AF recurrence postablation is probably associated with high cardiac parasympathetic activity, which can be assessed with deceleration capacity (DC) of heart rate. Given that the relationship between DC and AF recurrence is still controversial, this systematic review and meta‐analysis was performed to investigate the characteristics of DC in patients with and without AF recurrence, evaluating the prognostic value of DC in AF patients after CA. Methods: A literature search was systematically performed in the Embase, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases until October 01, 2023. The observational studies reporting either the pre‐ and postablation DC in both recurrence and non‐recurrence groups or the ratios based on DC for predicting AF recurrence were mainly included. Weighted mean differences (WMD) or odds ratios (OR) based on DC would be calculated with a random‐effect model, if heterogeneity estimated with the I 2 index and Q statistic was significant (I² > 50% or p < .05); otherwise, a fixed‐ effect model would be utilized. Results: A total of eight observational studies involving 914 AF patients treated with radiofrequency or cryoballoon ablation were included in this study. Ablation‐treated patients with AF recurrence had the higher DC postablation in relation to those without recurrence (WMD, 1.00; 95% confidence interval [CI], 0.33–1.67; p < .01), which was present up to 3 months of follow‐up (WMD, 1.54; 95% CI, 1.11–1.96; p < .01), whereas there was no statistical significance in DC before ablation between recurrence and non‐recurrence groups (WMD, 0.34; 95% CI, −0.12 to 0.79; p = .15). The high DC postablation was a risk factor for AF recurrence in ablation‐treated patients (OR, 2.17; 95% CI, 1.44–3.25; p < .01). Conclusion: The high DC postablation was associated with the risk of AF recurrence, suggesting that DC may act as a prognostic indicator in AF patients treated with CA. [ABSTRACT FROM AUTHOR]

Introduction: Through systematic scientific rigor, the CLOSE guided workflow was developed and has been shown to improve pulmonary vein isolation durability. However, this technique was developed at a time when using power‐controlled ablation catheters with conventional power ranges was the norm. There has been increased adoption of a high‐power and very high‐power short‐duration ablation practice propelled by the availability of the temperature‐controlled radiofrequency QDOT MICRO catheter. Methods: There are fundamental differences in biophysics between very high‐ powered temperature guided ablation and conventional ablation strategy that may impact patient outcomes. The catheter's design and ablation modes offer flexibility in technique while accommodating the individual operator's clinical discretion and preference to deliver a durable, transmural, and contiguous lesion set. Results: Here, we provide recommendations for 3 different workflows using the QDOT MICRO catheter in a step‐by‐step manner for pulmonary vein isolation based on our cumulative experience as early adopters of the technology and the data available in the scientific literature. Conclusions: With standardization, temperature‐controlled ablation with the QDOT MICRO catheter provides operators the flexibility of implementing different ablation strategies to ensure durable contiguous pulmonary vein isolation depending on patient characteristics. [ABSTRACT FROM AUTHOR]

Introduction: Atrio‐esophageal fistula after esophageal thermal injury (ETI) is one of the most devastating complications of available energy sources for atrial fibrillation (AF) ablation. Pulsed field ablation (PFA) uses electroporation as a new energy source for catheter ablation with promising periprocedural safety advantages over existing methods due to its unique myocardial tissue sensitivity. In preclinical animal studies, a dose‐dependent esophageal temperature rise has been reported. In the TESO‐PFA registry intraluminal esophageal temperature (TESO) changes in a clinical setting are evaluated. Methods: Consecutive symptomatic AF patients (62 years, 67% male, 61% paroxysmal AF, CHA2DS2Vasc Score 2) underwent first‐time PFA and were prospectively enrolled into our registry. Eight pulse trains (2 kV/2.5 s, bipolar, biphasic, x4 basket/flower configuration each) were delivered to each pulmonary vein (PV). Two extra pulse trains per PV in flower configuration were added for wide antral circumferential ablation. Continuous intraluminal esophageal temperature (TESO) was monitored with a 12‐pole temperature probe. Results: Median TESO change was statistically significant and increased by 0.8 ± 0.6°C, p <.001. A TESO increase ≥ 1°C was observed in 10/43 (23%) patients. The highest TESO measured was 40.3°C. The largest TESO difference (∆TESO) was 3.7°C. All patients remained asymptomatic considering possible ETI. No atrio‐esophageal fistula was reported on follow‐up. Conclusion: A small but significant intraluminal esophageal temperature rise can be observed in most patients during PFA. TESO rise over 40°C is rare. The clinical implications of the observed findings need to be further evaluated. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 67-year-old woman referred for ablation of atrial flutter, exploring the mechanism behind double atrial potentials recorded in the coronary sinus (CS) during the procedure. It discusses the complex anatomy of the CS and its connections to the left atrium (LA), examining how previous ablation procedures can alter the electrical activation pattern, leading to the manifestation of double atrial potentials in the CS electrode during atrial flutter.

Introduction: Pulmonary vein isolation (PVI) with thermal energy is characterized by concomitant ablation of the surrounding ganglionated plexi (GP). Pulsed‐field ablation (PFA) selectively targets the myocardium and seems associated with only negligible effects on the autonomic nervous system (ANS). However, little is known about the dynamic effects of PFA on the GP immediately after PVI. This study sought to investigate the degree and acute vagal modulation induced by the FarapulseTM PFA system during PVI compared with single‐shot thermal ablation. Methods: A total of 76 patients underwent first‐time PVI with either FarapulseTM PFA (PFA group, n = 40) or cryoballoon ablation (thermal ablation group, n = 36) for paroxysmal atrial fibrillation (AF). The effect on the ANS in the two groups was assessed before and after PVI with extracardiac vagal stimulation (ECVS). To capture any transient effects of PFA on the ANS, in a subgroup of PFA patients ECVS was repeated at three predefined timepoints: (1) before PVI (T0); (2) immediately after PVI (T1); and (3) 10 min after the last energy application (T2). Results: Despite similar baseline values, the vagal response induced by ECVS after PVI almost disappeared in the thermal ablation group but persisted in the PFA group (thermal group: 840 [706–1090] ms, p <.001 compared to baseline; PFA group: 11 466 [8720–12 293] ms, p =.70 compared to baseline). Intraprocedural vagal reactions (defined as RR increase >50%, transitory asystole, or atrioventricular block) occurred more frequently with PFA than thermal ablation (70% vs. 28%, p =.001). Moreover, heart rate 24 h post‐PVI increased more with thermal ablation than with PFA (16.5 ± 9.0 vs. 2.6 ± 6.1 beats/min, p <.001). In the subgroup of PFA patients undergoing repeated ANS modulation assessment (n = 11), ECVS demonstrated that PFA determined a significant acute suppression of the vagal response immediately after PVI (p <.001 compared to baseline), which recovered almost completely within 10 min. Conclusion: PVI with the FarapulseTM PFA system is associated with only transitory and short‐lasting vagal effects on the ANS which recover almost completely within a few minutes after ablation. The impact of this phenomenon on AF outcome needs to be further investigated. [ABSTRACT FROM AUTHOR]

Introduction: Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source‐sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. Methods: This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. Results: Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi‐atrial macro‐reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13‐month follow‐up. Conclusion: A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets. [ABSTRACT FROM AUTHOR]

Introduction: Measurement of the spatial ventricular gradient (SVG), spatial QRST angles, and other vectorcardiographic measures of myocardial electrical heterogeneity have emerged as novel risk stratification methods for sudden cardiac death and other adverse cardiovascular events. Prior studies of normal limits of these measurements included primarily young, healthy, White volunteers, but normal limits in older patients are unknown. The influence of race and body mass index (BMI) on these measurements is also unclear. Methods: Normal 12‐lead electrocardiograms (ECGs) from a single center were identified. Patients with abnormal cardiovascular, pulmonary, or renal history (assessed by International Classification of Disease [ICD‐9/ICD‐10] codes) or abnormal cardiovascular imaging were excluded. The SVG and QRST angles were measured and stratified by age, sex, and race. Multivariable linear regression was used to assess the influence of age, BMI, and heart rate (HR) on these measurements. Results: Among 3292 patients, observed ranges of SVG and QRST angles (peak and mean) differed significantly based on sex, age, and race. Sex differences attenuated with increasing age. Men tended to have larger SVG magnitude (60.4 [46.1–77.8] vs. 52.5 [41.3–65.8] mv*ms, p <.0001) and elevation, and more anterior/negative SVG azimuth (−14.8 [−25.1 to −4.3] vs. 1.3 [−9.8 to 10.5] deg, p <.0001) compared to women. Men also had wider QRST angles. Observed ranges varied significantly with BMI and HR. SVG and QRST angle measurements were robust to different filtering bandwidths and moderate fiducial point annotation errors, but were heavily affected by changes in baseline correction. Conclusions: Age, sex, race, BMI, and HR significantly affect the range of SVG and QRST angles in patients with normal ECGs and no known cardiovascular disease, and should be accounted for in future studies. An online calculator for prediction of these "normal limits" given demographics is provided at https://bivectors.github.io/gehcalc/. [ABSTRACT FROM AUTHOR]

Background: Substrate‐based ablation can treat uninducible or hemodynamically instability scar‐related ventricular tachycardia (VT). However, whether a correlation exists between the critical VT isthmus and late activation zone (LAZ) during sinus rhythm (SR) is unknown. Objective: To demonstrate the structural and functional properties of abnormal substrates and analyze the link between the VT circuit and abnormal activity during SR. Methods: Thirty‐six patients with scar‐related VT (age, 50.0 ± 13.7 years and 86.1% men) who underwent VT ablation were reviewed. The automatic rhythmia ultrahigh resolution mapping system was used for electroanatomic substrate mapping. The clinical characteristics and mapping findings, particularly the LAZ characteristics during SR and VT, were analyzed. To determine the association between the LAZ during the SR and VT circuits, the LAZ was defined as five activation patterns: entrance, exit, core, blind alley, and conduction barrier. Results: Forty‐five VTs were induced in 36 patients, 91.1% of which were monomorphic. The LAZ of all patients was mapped during the SR and VT circuits, and the consistency of the anatomical locations of the LAZ and VT circuits was analyzed. Using the ultrahigh resolution mapping system, interconversion patterns, including the bridge, T, puzzle, maze, and multilayer types, were identified. VT ablation enabled precise ablation of abnormal late potential conduction channels. Conclusion: Five interconversion patterns of the LAZ during the SR and VT circuits were summarized. These findings may help formulate more precise substrate‐based ablation strategies for scar‐related VT and shorter procedure times. [ABSTRACT FROM AUTHOR]

Introduction: Atrial fibrillation (AF) is a risk factor for reduced cerebral blood flow (CBF) and cognitive dysfunction, even in stroke‐free patients. We aimed to test the hypothesis that CBF and hippocampal blood flow (HBF), measured with arterial spin labeling magnetic resonance imaging (MRI), improve after catheter ablation of AF to achieve sinus rhythm (SR). Methods: A total of 84 stroke‐free patients (63.1 ± 9.1 years; paroxysmal AF, n = 50; non‐paroxysmal AF, n = 34) undergoing AF catheter ablation were included. MRI studies were done before, 3 months, and 12 months after the procedure with CBF and HBF measurements. Results: Baseline CBF and HBF values in 50 paroxysmal AF patients were used as controls. Baseline CBF was higher in patients with paroxysmal AF than with non‐paroxysmal AF (100 ± 32% vs. 86 ± 28%, p =.04). Patients with non‐paroxysmal AF had increased CBF 3 months after AF ablation (86 ± 28% to 99 ± 34%, p =.03). Differences in CBF and HBF were greater in the group with AF restored to SR (p <.01). Both CBF and HBF levels at 12 months were unchanged from the 3 months level. Successful rhythm control by catheter ablation was an independent predictor of an increase in CBF > 17.5%. The Mini‐Mental State Examination score improved after ablation (p =.02). Conclusion: SR restoration with catheter ablation was associated with improved CBF and HBF at 3 months, maintenance of blood flow, and improved cognitive function at 12 months. [ABSTRACT FROM AUTHOR]

Introduction: To investigate the optimal range of quantitative ablation index (AI) value during superior vena cava (SVC) electrical isolation by radiofrequency catheter ablation (RFCA). Methods: First, in a development cohort of patients with atrial fibrillation (AF), the RFCA with 40 W was performed to complete SVC isolation guided by the conduction breakthrough point from the right atrium to SVC. Then, the range of AI value was calculated by offline analysis on different segments of SVC. Lastly, for the validation of AF patients, the safety and effectiveness of SVC isolation with the optimized target range of AI value were evaluated with an additional adenosine test. Results: A total of 101 patients with AF were included in the study (44 patients in the development cohort/57 in the validation cohort). The segmental ablation strategy was applied in 70% of the patients. According to the offline analysis of the AI values in the development cohort, the target AI value range was set as 350–400. The success rate of SVC isolation in the validation cohort was significantly higher than that in the exploration cohort (100% vs. 90.9%, p =.02), and no complications occurred in the exploration cohort. During the adenosine test, the recovery rate of electrical conduction in SVC was significantly lower than that in the pulmonary vein (3.5% vs. 17.5%). Conclusion: The target AI value with a range from 350 to 400 is safe and effective for high‐power RFCA to complete SVC isolation. [ABSTRACT FROM AUTHOR]

Background: Pacing for vasovagal syncope is established. Two pacing algorithms are available. The rate‐drop‐response (RDR‐Medtronic) is triggered by falling heart rate acting with modified rate‐hysteresis. The closed loop stimulation or system (CLS‐Biotronik) is triggered by impedance changes in the right ventricle reflecting falling volume and rising contractility. These are very different physiologically. Both algorithms carry favorable reports in clinical use. Methods: A randomized‐controlled superiority trial is proposed to compare the two algorithms for the control of vasovagal syncope in patients for whom pacing is indicated by current guidelines in North America and Europe. Available recent evidence may be seen as supporting superiority of CLS. No comparison between the two algorithms has been made. In this trial, patients will be centrally randomized to one or other algorithm on a 1:1 basis. Two‐hundred‐seventy‐six patients in each group will be recruited. Sample size is determined using a confidence interval of 95%, a power of 90%, and a drop‐out rate of 10% to detect an 11% difference between CLS and RDR. Recurrent symptom comparison will be made by an independent committee. The Co‐primary endpoints will be recurrent syncope burden compared with that in 24‐months preimplant, and occurrence of syncope in 24‐months follow‐up. Each outcome will be compared between the two algorithms. Secondary endpoints will be program and drug therapy changes over 24‐months follow‐up and quality of life by questionnaire at baseline,1 and 2 years. Results and Conclusions: These are anticipated to clarify the device algorithm choice and, therefore, to improve patient care. [ABSTRACT FROM AUTHOR]

Introduction: Improved sinus rhythm (SR) maintenance rates have been achieved in patients with persistent atrial fibrillation (AF) undergoing pulmonary vein isolation plus additional ablation of low voltage substrate (LVS) during SR. However, voltage mapping during SR may be hindered in persistent and long‐persistent AF patients by immediate AF recurrence after electrical cardioversion. We assess correlations between LVS extent and location during SR and AF, aiming to identify regional voltage thresholds for rhythm‐independent delineation/detection of LVS areas. (1) Identification of voltage dissimilarities between mapping in SR and AF. (2) Identification of regional voltage thresholds that improve cross‐rhythm substrate detection. (3) Comparison of LVS between SR and native versus induced AF. Methods: Forty‐one ablation‐naive persistent AF patients underwent high‐definition (1 mm electrodes; >1200 left atrial (LA) mapping sites per rhythm) voltage mapping in SR and AF. Global and regional voltage thresholds in AF were identified which best match LVS < 0.5 mV and <1.0 mV in SR. Additionally, the correlation between SR‐LVS with induced versus native AF‐LVS was assessed. Results: Substantial voltage differences (median: 0.52, interquartile range: 0.33–0.69, maximum: 1.19 mV) with a predominance of the posterior/inferior LA wall exist between the rhythms. An AF threshold of 0.34 mV for the entire left atrium provides an accuracy, sensitivity and specificity of 69%, 67%, and 69% to identify SR‐LVS < 0.5 mV, respectively. Lower thresholds for the posterior wall (0.27 mV) and inferior wall (0.3 mV) result in higher spatial concordance to SR‐LVS (4% and 7% increase). Concordance with SR‐LVS was higher for induced AF compared to native AF (area under the curve[AUC]: 0.80 vs. 0.73). AF‐LVS < 0.5 mV corresponds to SR‐LVS < 0.97 mV (AUC: 0.73). Conclusion: Although the proposed region‐specific voltage thresholds during AF improve the consistency of LVS identification as determined during SR, the concordance in LVS between SR and AF remains moderate, with larger LVS detection during AF. Voltage‐based substrate ablation should preferentially be performed during SR to limit the amount of ablated atrial myocardium. [ABSTRACT FROM AUTHOR]

Background: Atrial tachycardia (AT) is a commonly encountered rhythm disorder in patients with underlying atrial scar. The role of atrial late activation mapping during sinus rhythm to predict the critical isthmus (CI) of AT has yet to be systematically evaluated. We aimed to investigate the relationship between the functional substrate mapping (FSM) characteristics and the CI of reentrant ATs in patients with underlying atrial low‐voltage areas. Methods: Patients with history of left AT who underwent catheter ablation with 3D mapping using high‐density mapping were enrolled. Voltage map and isochronal late activation mapping were created during sinus/paced rhythm to detect deceleration zones (DZ). Electrograms with continuous‐fragmented morphology were also tagged. After induction of AT, activation mapping was performed to detect CI of the tachycardia. Atrial tachyarrhythmia (ATa) recurrence was defined as detection of atrial fibrillation or AT (≥30 s) during the follow‐up. Results: Among 35 patients [mean age: 62 ± 9, gender: 25 (71.5%) female] with left AT, a total of 42 reentrant ATs induced. Voltage mapping during sinus rhythm revealed low‐voltage area of 37.1 ± 23.8% of the left atrium. The mean value of bipolar voltage, EGM duration, and conduction velocity during sinus rhythm corresponding to CI of ATs were 0.18 ± 0.12 mV, 133 ± 47 ms, and 0.12 ± 0.09 m/s, respectively. Total number of DZs per chamber was 1.5 ± 0.6, which were located in the low‐voltage zone (<0.5 mV) detected by high‐density mapping. All CIs of reentry were colocalized with DZs detected during FSM. The positive predictive value of DZs to detect CI of inducible ATs is 80.4%. Freedom from ATa after the index procedure was 74.3% during a mean follow‐up of 12.2 ± 7.5 months. Conclusion: Our findings demonstrated the utility of FSM during sinus rhythm to predict the CI of AT. DZs displayed continuous‐fragmented signal morphology with slow conduction which may guide to tailor ablation strategy in case of underlying atrial scar. [ABSTRACT FROM AUTHOR]

An editorial focuses on advancements in predicting the site of origin for outflow tract ventricular arrhythmias (OT-VAs), crucial for successful catheter ablation procedures. It highlights the challenges posed by the anatomical complexity of OT-VAs, which can arise from various structures within the heart's outflow tracts, such as the right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT).

Introduction: Torsades de Pointes (TdP) is a potentially lethal polymorphic ventricular tachydysrhythmia associated with and caused by prolonged myocardial repolarization. However, prediction of TdP is challenging. We sought to determine if electrocardiographic myocardial repolarization heterogeneity is necessary and predictive of TdP. Methods: We performed a case control study of TdP at a large urban hospital. We identified cases based on a hospital center electrocardiogram (ECG) database search for tracings from 1/2005 to 6/2019 with heart rate corrected QT (QTc) > 500, QRS < 120, and heart rate (HR) < 60, and a subsequent natural language search of electronic health records for the terms: TdP, polymorphic ventricular tachycardia, sudden cardiac death, and relevant variants. Controls were drawn in a 2:1 ratio to cases from a similar pool of ECGs, and matching for QTc, heart rate, sex, and age. We abstracted historical, laboratory, and ECG data using detailed written instructions and an electronic database. We included a second blinded data abstractor to test data abstraction and manual ECG measurement reliability. We used General Electric (GE) QT Guard software for automated repolarization measurements. We compared groups using unpaired statistics. Results: We included 75 cases and 150 controls. The number of current QTc prolonging medications and serum electrolytes were substantially the same between the two groups. We found no significant difference in measures of QT or T wave repolarization heterogeneity. Conclusion: Electrocardiographic repolarization heterogeneity is not greater in otherwise unselected patients with QTc prolongation who suffer TdP and does not appear predictive of TdP. However, previous observations suggest specific repolarization characteristics may be useful for defined patient subgroups at risk for TdP. [ABSTRACT FROM AUTHOR]

Introduction: Variability of the bipolar atrial electrogram amplitude may affect voltage maps created during ablation procedures, and thus also the extent of ablations. Therefore, the aim of the study was to assess the beat‐to‐beat electrogram amplitude variability in the left atrium in patients undergoing atrial fibrillation ablation. Methods: In 11 patients undergoing ablation for atrial fibrillation, 362 mapping points were collected in two series. At each point, three consecutive beats were recorded and verified including the bipolar electrogram amplitude, contact force (CF), and orientation of the catheter tip. The repeatability and reproducibility of obtained measurements between consecutive beats and series were assessed by the Pearson correlation coefficient (r), the Bland‐Altman test, repeatability coefficient (RC), relative standard deviation (RSD), and concordance correlation coefficient (CCC). Results: A total of 1086 beats were analyzed. The correlation coefficient for bipolar atrial electrogram amplitude for the first two beats, and for the first and the third beats were 0.94 and 0.86, respectively. The average of differences between the first two beats and between the first and the third beats were 0.06 and 0.13 mV with 95% limits of agreement (LoA) within ±0.98 and ±1.74 mV, respectively. For CF values ≤5 and ≥20 g, the 95% LoA were narrower compared to other CF ranges and were ±0.49 and ±0.71 mV from the average value, respectively. When the analyzes were performed within the predefined ranges of bipolar electrogram amplitude: 0.05–1; 1–2; 2–3 mV, the 95% LoA were within ±0.33, ±0.98, and ±0.84 mV from the average value, respectively. RC and RSD were 1.41 mV and 20.8%, respectively. For repeated measurement between series, CCC ranged from 0.67 to 0.71 and the 95% LoA were within ±2.7 to 2.9 mV from the average value. Conclusion: Bipolar atrial electrogram amplitude recorded at a given site during ablation procedures is variable to an extent that may be clinically relevant. The magnitude of the observed variability is greater during remapping. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 33-year-old female with recurrent episodes of wide‐QRS tachycardia. Topics include responsive to intravenous adenosine referred to the arrhythmia center for undergoing an electrophysiological study (EPS); and constant P‐QRS intervals during WQR not supporting the hypothesis of isorhythmic competition with an accelerated idioventricular rhythm (AIVR).

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: 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]

Introduction: Multielectrode mapping (MEM) and automated point collection are important enhancements to substrate mapping in ventricular tachycardia ablation. The effects of tissue contact and respiration on electrogram voltage with differing depolarization wavefronts with MEM catheters are unclear. Methods: Bipolar and unipolar voltages were collected from control (n = 5) and infarcted (n = 7) animals with a multispline MEM catheter. Electro‐anatomic maps were created in sinus rhythm, and right and left ventricular pacing. Analysis was performed across three collections: standard settings (SS), respiratory‐phase gating (RG), and electrode‐tissue proximity (TP). Comparison was made to scar detected by cardiac MRI (cMRI). Results: Compared to SS and RG acquisition, median bipolar and unipolar voltages were higher using TP, regardless of the depolarization wavefront. In infarct animals, bipolar voltages were 30.7%–50.5% higher for bipolar and 8.7%–13.8% higher on unipolar voltages with TP, compared to SS. The effect of RG on bipolar and unipolar voltages was minimal. Percentage of local abnormal ventricular activities was not impacted by acquisition settings or wavefront direction in infarct animals. Compared with cMRI defined scar, all three acquisition settings overestimated scar area using standard voltage‐based cutoffs. RG improved the low voltage area concordance with MRI by 1.6%–5.1% whereas TP improved by 5.9%–8.4%. Conclusions: High density voltage mapping with a MEM catheter is influenced by point collection settings. Tissue contact filters reduced low voltage areas and improved agreement with cMRI fibrosis in infarcted ovine hearts. These findings have critical implications for optimizing filter settings for high density substrate mapping in the left ventricle. [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]

Background: It remains unclear why some patients with the same heart rate during an atrial fibrillation (AF) have subjective symptoms, whereas others do not. We assessed the hypothesis that different responses of arterial and left atrial blood pressures to rapid stimulation may be associated with the symptoms of AF. Methods: A total of 110 patients who underwent catheter ablation for paroxysmal AF were retrospectively studied. Asymptomatic AF was defined as a European Heart Rhythm Association score of Ⅰ for AF‐related symptoms. The left atrial pressure (LAP) was measured during sinus rhythm (SR), in 10 pacing per minute (ppm) increments from 100 ppm to the Wenckebach block rate in high right atrial pacing. Results: Asymptomatic AF was observed in 19/110 patients (17%). Patients with symptomatic AF showed higher E/e′ ratio and gradual LAP increase that was dependent on the pacing rate. Patients with asymptomatic AF had decreased LAP at 100 ppm compared that at SR, and thereafter, LAP gradually increased depending on the pacing rate. The rate of LAP change compared to that at SR was significantly lower in patients with asymptomatic AF than that in patients with symptomatic AF. The rate of LAP change was independently associated with AF symptoms. Conclusion: Patients with asymptomatic AF showed lower E/e′ ratio and decreased LAP at 100 ppm to rapid stimulation, followed by a steady increase in LAP afterwards. Factors other than left ventricular diastolic dysfunction may be involved in AF symptoms. [ABSTRACT FROM AUTHOR]

An editorial is presented which discusses the challenges in addressing perimitral atrial tachycardia (PMAT) during catheter ablation for atrial fibrillation (AF) and the common practice of performing empirical mitral isthmus block as an adjunctive therapy. The STAR AF II trial's findings, indicating no reduction in AF recurrence with empirical linear ablation, prompt the exploration of better methods for creating durable mitral isthmus block.

The article describes a case of a male patient who was hospitalized due to symptomatic palpitations. Topics mentioned include the mechanism of a narrow QRS tachycardia with different atrial sequence during ventricular pacing, the atrial activation sequences of ventriculoatrial conduction, and the rare existence of atrioventricular nodal reentrant tachycardia with retrograde activation.

Introduction: Cardiac surgery may influence occurrence and persistence of atrial fibrillation (AF). In patients with a history of cardiac surgery and postoperative pacemaker or implantable cardioverter defibrillator implantation we attempted to quantify AF characteristics and investigate factors that influence AF recurrence. Methods: In 426 patients (319 male; age: 73 SD: 9 years) with a history of cardiac surgery (364 CABG; 69 mitral valve; 57 aortic valve and 59 combination procedures) the heart rhythm history (mean: 351 days SD: 54 days) was reconstructed and investigated for AF recurrence patterns. Results: AF developed and subsequently recurred in 75% of patients (n = 320). The mean AF burden in these patients was 0.21 (21% of the total observed time spent in AF) and 4085 episodes of AF were observed and analyzed. AF episodes spontaneously terminated within 24 h (n = 2509), 48 h (n = 700), 72 h (n = 279), and 1 week (n = 31). The probability of spontaneous conversion to sinus rhythm (SR) decreased with time spent in AF and plateaued after approximately 7 days. Patient age, LVEF and presence of coronary artery disease significantly influenced the probability of spontaneous conversion to SR. Type of cardiac surgery also significantly influenced AF episode characteristics. Conclusion: AF episodes are common in patients with a history of cardiac surgery. Spontaneous conversion to SR diminishes with increasing time spent in AF and is influenced by AF characteristics and several patient‐related factors. Continuous monitoring can provide detailed information about AF recurrence that may immensely improve our understanding and influence the clinical management of AF. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to evaluate whether device measured amplitudes of atrial electrogram (AEGM) would change when measured in sinus rhythm (SR) transitioning to paroxysmal atrial fibrillation (AF) from previous steady SR, and significance of such change. Methods: From the IMPACT trial's database we selected two groups; (A) those who developed AF (n = 164), and (B) propensity‐matched control (n = 459) who stayed in SR during continuous Home Monitoring (HM) to compare AEGMs amplitudes at baseline SR and transition phase. Results: During 420.0 ± 349.2 days (mean ± SD) from first postenrollment HM transmission to AF event transmission in Group A, and corresponding 515.3 ± 407.0 days in Group B, baseline and transition AEGM amplitude were 2.88 ± 1.146 and 2.74 ± 1.186 mV, respectively, for Group A (p =.1), and 2.88 ± 1.155 and 2.79 ± 1.145, respectively, for Group B (p <.005). Comparison of differences of AEGM amplitude, 0.14 ± 1.072 mV in Group A and 0.09 ± 0.893 mV in Group B were insignificant (p =.3). Age, sex, and hypertension identified as confounders had no association to AEGM changes (p = NS). Conclusions: Independent of age, sex, and hypertension, AEGMs amplitudes decline over a long period of time in patients with defibrillators and substrate for AF. The significance of such change remains unclear as it occurs whether patients develop AF or not, but raises a possibility of progressive atrial myopathy that patients with substrate for AF may be predisposed to. [ABSTRACT FROM AUTHOR]

Background: Unfortunately, some patients with long QT syndrome (LQTS) experience breakthrough cardiac events (BCEs) despite maximal therapy. Small studies have shown that refractory LQTS cases may benefit from intentional permanent atrial pacing (IPAP). As such, we sought to determine the genotype‐specific utilization and efficacy of IPAP in a single‐center LQTS registry. Methods and Results: In this retrospective study, electronic medical records from 1065 patients diagnosed with LQTS were used to identify individuals that received IPAP. Pre‐ and post‐IPAP heart rate, heart rate‐corrected QT (QTc) values, annual BCE rate, and IPAP‐related complications were compared between genotypes. BCEs were defined as LQTS‐associated syncope/seizures, sustained ventricular arrhythmia (VA)‐terminating ICD therapies, and sudden cardiac arrest/death. Overall, 52 out of 1065 LQTS patients received adjunctive IPAP therapy (77% female; median age 18.5 [interquartile range, 1–35.5] years; 73% with prior VA). Over an average IPAP follow‐up of 121 ± 82 months, the average heart rate increased from 65.8 ± 20.4 bpm to 78.9 ± 17.1 bpm; (p <.01) and the average QTc decreased from 533.4 ± 66.6 to 488.3 ± 52.4 ms; (p <.01). The mean BCE rate dropped from 0.88 to 0.19 per patient‐year (p =.01), driven by a marked decrease in the LQT2 cohort (1.01 BCE/year to 0.02 BCE/year; p =.003). No serious IPAP‐related complications were observed. Conclusion: In high‐risk LQTS patients, namely those with recalcitrant LQT2, IPAP appears to be a safe and efficacious adjunct therapy. The beneficial effects of IPAP may stem from attenuating the QTc and circumventing a pause‐dependent trigger. Whether IPAP might obviate the need for an ICD in some instances warrants further study. [ABSTRACT FROM AUTHOR]

Introduction: Patients undergoing evaluation for an inherited arrhythmia syndrome undertake a series of ambulatory investigations including 24‐h Holter monitor, exercise treadmill testing (ETT), and others. Patch monitors may simplify the evaluation, providing accurate arrhythmia evaluation and QT assessment. Methods and Results: Patients referred for evaluation of an inherited arrhythmia syndrome underwent standard investigations, including 12‐lead electrocardiography (ECG), 24‐h Holter monitoring, ETT, along with supplemental monitoring using a 7‐day ECG patch monitor. Heart rates (HR), corrected QT intervals (QTc), and ectopic burden were compared across monitoring modalities. Among 35 patients that wore the patch monitor, the median age was 39 years (54% male). There was intermediate correlation between resting HR across modalities (r =.58–.66) and poor correlation of peak HR (r =.27–.39). There was intermediate correlation between resting QTc intervals across modalities (r =.72–.77) but negligible correlation between QTc intervals at peak HR across modalities (r = −.01 to −.06). There was good correlation in PAC and PVC ectopic burden across the Holter and patch monitor. Conclusion: Patch monitors may simplify the evaluation of patients for an inherited arrhythmia syndrome and provide resting QT assessment over time. However, QTc interval comparison at peak HRs remains variable, and may be limited by the single‐lead ECG vector when using the patch monitor. Apart from QTc intervals at peak HR, patch monitors demonstrated good correlation with the ECG and Holter monitor for other parameters. [ABSTRACT FROM AUTHOR]

Introduction: High‐power short‐duration (HPSD) ablation is a novel strategy using contact force‐sensing catheters optimized for power‐controlled radiofrequency ablation for atrial fibrillation (AF). This study investigates the outcomes of HPSD (50 W delivered for up to 15 s, Lesion Size Index of 5–6) compared to standard‐power standard‐duration (SPSD) (20–25 W until 400–500 gram seconds, up to 60 s) and temperature‐controlled noncontact (TCNC) (20‐40 W up to 60 s of ablation) settings. Methods: We studied consecutive cases of patients with AF undergoing pulmonary vein isolation with TCNC, SPSD, and HPSD between January 7th, 2013 and January 11th, 2019. Procedural data collected include time to isolate the left (LPVT) and right pulmonary veins (RPVT), total ablation time (TAT), and radiofrequency ablation delivery time (RADT). Clinical data collected include sinus rhythm maintenance postprocedure. Results: One hundred and seventy‐one patients were studied (44 TCNC, 51 SPSD, 76 HPSD). RADT was shorter when comparing HPSD to SPSD (25 vs. 41 min; p <.01), HPSD to TCNC (25 vs. 76 min; p <.01), and SPSD to TCNC groups (41 vs. 76 min; p <.01). TAT, LPVT, and RPVT were reduced between HPSD versus SPSD, HPSD versus TCNC, and SPSD versus TCNC groups, respectively (p <.01). There was no difference in sinus rhythm maintenance by Kaplan–Meier survival analysis (log rank test p =.12), after 3 or 12 months between groups overall, and when stratified by AF type, left atrial volume, CHA2DS2‐VASc score, or left ventricular ejection fraction. Conclusion: AF ablation with HPSD reduced procedure times with similar sinus rhythm maintenance compared to SPSD and TCNC. [ABSTRACT FROM AUTHOR]