Lower contact force predicts right pulmonary vein carina breakthrough after ablation index-guided pulmonary vein isolation using high-power short-duration.

INTRODUCTION: Carina breakthrough (CB) at the right pulmonary vein (RPV) can occur after circumferential pulmonary vein isolation (PVI) due to epicardial bridging or transient tissue edema. High-power short-duration (HPSD) ablation may increase the incidence of RPV CB. Currently, the surrogate of ablation parameters to predict RPV CB is not well established. This study investigated predictors of RPV CB in patients undergoing ablation index (AI)-guided PVI with HPSD. METHODS: The study included 62 patients with symptomatic atrial fibrillation (AF) who underwent AI-guided PVI using HPSD. Patients were categorized into two groups based on the presence or absence of RPV CB. Lesions adjacent to the RPV carina were assessed, and CB was confirmed through residual voltage, low voltage along the ablation lesions, and activation wavefront propagation. RESULTS: Out of the 62 patients, 21 (33.87%) experienced RPV CB (Group 1), while 41 (66.13%) achieved first-pass RPV isolation (Group 2). Despite similar AI and HPSD, patients with RPV CB had lower contact force (CF) at lesions adjacent to the RPV carina. Receiver operating characteristic (ROC) curve analysis identified CF < 10.5 g as a predictor of RPV CB, with 75.7% sensitivity and 56.2% specificity (area under the curve: 0.714). CONCLUSION: In patients undergoing AI-guided PVI with HPSD, lower CF adjacent to the carina was associated with a higher risk of RPV CB. These findings suggest that maintaining higher CF during ablation in this region may reduce the occurrence of RPV CB.

Fibroblasts Drive Metabolic Reprogramming in Pacemaker Cardiomyocytes.

BACKGROUND: The sino atrial node (SAN) is characterized by the microenvironment of pacemaker cardiomyocytes (PCs) encased with fibroblasts. An altered microenvironment leads to rhythm failure. Operable cell or tissue models are either generally lacking or difficult to handle. The biological process behind the milieu of SANs to evoke pacemaker rhythm is unknown. We explored how fibroblasts interact with PCs and regulate metabolic reprogramming and rhythmic activity in the SAN. METHODS: Tbx18 (T-box transcription factor 18)-induced PCs and fibroblasts were used for cocultures and engineered tissues, which were used as the in vitro models to explore how fibroblasts regulate the functional integrity of SANs. RNA-sequencing, metabolomics, and cellular and molecular techniques were applied to characterize the molecular signals underlying metabolic reprogramming and identify its critical regulators. These pathways were further validated in vivo in rodents and induced human pluripotent stem cell-derived cardiomyocytes. RESULTS: We observed that rhythmicity in Tbx18-induced PCs was regulated by aerobic glycolysis. Fibroblasts critically activated metabolic reprogramming and aerobic glycolysis within PCs, and, therefore, regulated pacemaker activity in PCs. The metabolic reprogramming was attributed to the exclusive induction of Aldoc (aldolase c) within PCs after fibroblast-PC integration. Fibroblasts activated the integrin-dependent mitogen-activated protein kinase-E2F1 signal through cell-cell contact and turned on Aldoc expression in PCs. Interruption of fibroblast-PC interaction or Aldoc knockdown nullified electrical activity. Engineered Tbx18-PC tissue sheets were generated to recapitulate the microenvironment within SANs. Aldoc-driven rhythmic machinery could be replicated within tissue sheets. Similar machinery was faithfully validated in de novo PCs of adult mice and rats, and in human PCs derived from induced pluripotent stem cells. CONCLUSIONS: Fibroblasts drive Aldoc-mediated metabolic reprogramming and rhythmic regulation in SANs. This work details the cellular machinery behind the complex milieu of vertebrate SANs and opens a new direction for future therapy.

Feasibility of Auto-Quantified Epicardial Adipose Tissue in Predicting Atrial Fibrillation Recurrence After Catheter Ablation.

BACKGROUND: The aim of this study was to build an auto-segmented artificial intelligence model of the atria and epicardial adipose tissue (EAT) on computed tomography (CT) images, and examine the prognostic significance of auto-quantified left atrium (LA) and EAT volumes for AF. METHODS AND RESULTS: This retrospective study included 334 patients with AF who were referred for catheter ablation (CA) between 2015 and 2017. Atria and EAT volumes were auto-quantified using a pre-trained 3-dimensional (3D) U-Net model from pre-ablation CT images. After adjusting for factors associated with AF, Cox regression analysis was used to examine predictors of AF recurrence. The mean (±SD) age of patients was 56±11 years; 251 (75%) were men, and 79 (24%) had non-paroxysmal AF. Over 2 years of follow-up, 139 (42%) patients experienced recurrence. Diabetes, non-paroxysmal AF, non-pulmonary vein triggers, mitral line ablation, and larger LA, right atrium, and EAT volume indices were linked to increased hazards of AF recurrence. After multivariate adjustment, non-paroxysmal AF (hazard ratio [HR] 0.6; 95% confidence interval [CI] 0.4-0.8; P=0.003) and larger LA-EAT volume index (HR 1.1; 95% CI 1.0-1.2; P=0.009) remained independent predictors of AF recurrence. CONCLUSIONS: LA-EAT volume measured using the auto-quantified 3D U-Net model is feasible for predicting AF recurrence after CA, regardless of AF type.

Three-dimensional mapping and superior approach for catheter ablation in patients without inferior vena cava access.

Catheter ablation for tachyarrhythmia via superior approach has been used in patients without possible inferior vena cava access such as in cases of venous occlusion or complex anomaly. Difficulty in catheter manipulation, instability, number of required vascular access, and radiation exposure of operator had been described in the procedure. Application of three-dimensional (3-D) mapping system in catheter ablation via superior approach could navigate the guiding catheter and provide more precise ablation. We reported four cases receiving catheter ablation due to atrioventricular nodal reentry tachycardia, atrial fibrillation, and right ventricular arrhythmia via superior approach facilitated by 3-D mapping system with fewer vascular access and catheters.

Characterization and identification of atrial fibrillation drivers in patients with nonparoxysmal atrial fibrillation using simultaneous amplitude frequency electrogram transform.

INSTRUCTION: We hypothesized that real-time simultaneous amplitude frequency electrogram transform (SAFE-T) during sinus rhythm (SR) is able to identify and characterize the drivers of atrial fibrillation (AF) in nonparoxysmal (NP) AF. METHODS: Twenty-one NPAF patients (85.71% males, mean age 52 years old) underwent substrate mapping during SR (SAFE-T and voltage) and during AF (complex fractionated atrial electrograms [CFAE] and similarity index [SI]). After pulmonary veins isolation, extensive substrate ablation was performed with the endpoint of procedural termination or elimination of all SI sites (>63% similarities). Sites with procedural termination and non-termination sites were tagged for postablation SR analysis using SAFE-T. RESULTS: In 74 CFAE sites identified (average of 3 ± 2 sites per person), 28 (37.84%) were identified as termination sites demonstrating a high SI compared with the non-termination sites (80.11 ± 9.57% vs. 45.96 ± 13.38%, p < .001) during AF. During SR, these termination sites have high SAFE-T values and harbor a highly resonant, localized, repetitive high frequency components superimposed in the low frequency components compared with non-termination sites (5.70 ± 3.04 vs. 1.49 ± 1.66 Hz·mV, p < .001). In the multivariate analysis, the termination sites have higher SAFE-T and SI value (p < .001). CONCLUSION: AF procedural termination sites harbored signal characteristics of repetitive, high frequency component of individualized electrogram during SR, which can be masked by the low frequency fractionated electrogram and are difficult to see from the bipolar electrogram. Thus, SAFE-T mapping is feasible in identifying and characterizing sites of AF drivers.

Insight of electrocardiographic and electrophysiological parameters on the left ventricular function in patients with ventricular arrhythmia from left ventricular summit.

INTRODUCTION: Ventricular arrhythmia (VA) commonly originate from the left ventricular summit (LVS) and results in left ventricular (LV) dysfunction in some patients; however, factors related to LV cardiomyopathy have not been well elucidated. Therefore, this study aimed to investigate the risk factors for LV cardiomyopathy and the outcomes of patients with LVS VA. METHODS: Between 2013 and 2018, a total of 139 patients (60.7% men; mean age 53.2 ± 13.9 years old) underwent catheter ablation for LVS VA in two centers. Detailed patient demographics, electrocardiograms, electrophysiological characteristics, and clinical outcomes were analyzed. LV cardiomyopathy was defined as left ventricular ejection fraction (LVEF) <50%. RESULTS: Acute procedural success was achieved in 92.8% of patients. There were 40 patients (28.8%) with LV cardiomyopathy, and the mean LVEF improved from 37.5 ± 9.3% to 48.5 ± 10.2% after ablation (p < .001). After multivariate analysis, the independent factors of LV dysfunction were wider QRS duration (QRSd) of the VA (odds ratio [OR] 1.02; 95% confidence interval [CI]: 1.00-1.04; p = .046) and the absolute earliest activation time discrepancy (AEAD) between epicardium and endocardium (OR 1.05; 95% CI: 1.00-1.09; p = .048). After ablation, the LV function was completely recovered in 20 patients (50%). The factors for LV dysfunction without recovery included wider premature ventricular complex (PVC) QRSd (OR 1.09; 95% CI: 1.02-1.17; p = .012) and poorer LVEF (OR 0.85; 95% CI: 0.74-0.97; p = .020). CONCLUSION: In patients with VA from the LVS, PVC QRSd and AEAD are factors associated with deteriorating LV systolic function. Catheter ablation can reverse LV remodeling. Narrower QRSd and better LVEF are associated with better recovery of LV function after ablation.

Factors predicting the progression from paroxysmal to persistent atrial fibrillation despite an index catheter ablation.

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.

Harnessing cell reprogramming for cardiac biological pacing.

Electrical impulses from cardiac pacemaker cardiomyocytes initiate cardiac contraction and blood pumping and maintain life. Abnormal electrical impulses bring patients with low heart rates to cardiac arrest. The current therapy is to implant electronic devices to generate backup electricity. However, complications inherent to electronic devices remain unbearable suffering. Therefore, cardiac biological pacing has been developed as a hardware-free alternative. The approaches to generating biological pacing have evolved recently using cell reprogramming technology to generate pacemaker cardiomyocytes in-vivo or in-vitro. Different from conventional methods by electrical re-engineering, reprogramming-based biological pacing recapitulates various phenotypes of de novo pacemaker cardiomyocytes and is more physiological, efficient, and easy for clinical implementation. This article reviews the present state of the art in reprogramming-based biological pacing. We begin with the rationale for this new approach and review its advances in creating a biological pacemaker to treat bradyarrhythmia.

Ablation of atrial fibrillation and dementia risk reduction during long-term follow-up: a nationwide population-based study.

AIMS: This study investigated the epidemiological characteristics of new-onset dementia in patients with atrial fibrillation (AF) and the association of catheter ablation with different subtypes of dementia. METHODS AND RESULTS: We conducted a population-based, retrospective cohort study using data from the Taiwan National Health Insurance Research Database. In total, 136 774 patients without a history of dementia were selected after 1:1 propensity score matching based on age (with AF vs. without AF). A competing risk model was used to investigate the three subtypes of dementia: Alzheimer's disease, vascular dementia, and other/mixed dementia. Inverse probability of treatment weighting (IPTW) was performed to minimize the impact on dementia risk due to the imbalanced baseline characteristics. After a median follow-up period of 6.6 years, 8704 events of new-onset dementia occurred. Among all AF patients developing dementia, 73% were classified as having Alzheimer's disease, 16% as having vascular dementia, and 11% as having other/mixed dementia. The cumulative incidence of dementia in AF patients was higher than those without AF (log-rank test: P < 0.001 for both before and after IPTW). In patients with AF undergoing catheter ablation, the total dementia risk decreased significantly [P = 0.015, hazard ratio (HR): 0.74, 95% confidence interval (CI): 0.58-0.94] after multivariable adjustment, but not for the subtype of vascular dementia (P = 0.59, HR: 0.86, 95% CI: 0.49-1.50). CONCLUSION: Patients with AF have a higher incidence of all types of dementia, including Alzheimer's disease, vascular dementia, and a mixed type of dementia. Alzheimer's disease is less likely to occur in patients with AF undergoing catheter ablation.

Comparison of Long-Term Clinical Outcomes Between Segmental and Circumferential Pulmonary Vein Isolation in Patients Undergoing Repeat Atrial Fibrillation Ablation.

BACKGROUND: Circumferential pulmonary vein isolation (CPVI) has supplanted segmental PVI (SPVI) as standard procedure for atrial fibrillation (AF). However, there is limited evidence examining the efficacy of these strategies in redo ablations. In this study, we investigated the difference in recurrence rates between SPVI and CPVI in redo ablations for PV reconnection.Methods and Results: This study retrospectively enrolled 543 patients who had undergone AF ablation between 2015 and 2017. Among them, 167 patients (30.8%, including 128 male patients and 100 patients with paroxysmal AF) underwent redo ablation for recurrent AF. Excluding 26 patients without PV reconnection, 141 patients [90 patients of SPVI (Group 1) and 51 patients of CPVI (Group 2)] were included. The AF-free survival rates were 53.3% and 56.9% in Group 1 and Group 2, respectively (P=0.700). The atrial flutter (AFL)-free survival rates were 90% and 100% in Group 1 and Group 2, respectively (P=0.036). The ablation time was similar between groups, and there no major complications were observed. CONCLUSIONS: For redo AF ablation procedures, SPVI and CPVI showed similar outcomes, except for a higher AFL recurrence rate for SPVI after long-term follow-up (>2 years). This may be due to a higher probability of residual PV gaps causing reentrant AFL.

Fractal complexity alternations in paroxysmal atrial fibrillation patients with and without recurrence after pulmonary vein isolation.

BACKGROUND: Pulmonary vein isolation (PVI) is a cornerstone therapy for paroxysmal atrial fibrillation (PAF). The variations in nonlinear heart rate variability (HRV) between patients with and without recurrences remain unclear. We aimed to characterize the nonlinear HRV before and after PVI in patients with and without recurrence. METHODS: Twenty-five drug-refractory PAF patients (56.0 ± 9.1 years old, 20 males) who received PVI were enrolled. Holter electrocardiography were performed before, 1-3, and 6-12 months after PVI. After 8.2 ± 2.5 months of follow-ups after PVI, patients were divided into two groups: the recurrence (n = 8) and non-recurrence (n = 17) groups. Linear and nonlinear HRV variables were analyzed, including the Poincaré Plot analysis and the Detrended Fluctuation Analysis (DFA). RESULTS: The non-recurrence group, but not the recurrence group, had decreased high-frequency component (HF), the root mean square of successive RR interval differences (RMSSD), and the Poincaré Plot index SD1 1-3 months after PVI and increased DFAslope2 6-12 months after PVI. The non-recurrence group's LF/HF ratio and DFAslope1 decreased significantly 1-3 and 6-12 months after PVI, respectively, whereas there was no significant change in the recurrence group after PVI. CONCLUSIONS: Significantly reduced vagal tone 1-3 months after PVI, increased long-term fractal complexity 6-12 months after PVI, and decreased sympathetic tone as well as short-term fractal complexity 1-3 and 6-12 months after PVI led to a better AF-free survival after PVI. These findings suggest that neuromodulation and heart rate dynamics play crucial roles in AF recurrence following PVI.

The Role of Large Animal Models in Cardiac Regeneration Research Using Human Pluripotent Stem Cell-Derived Cardiomyocytes.

PURPOSE OF REVIEW: Heart failure leads to high mortality. The failing myocardium cannot often be rescued as heart regeneration is mostly compromised by disease progress. Stem cell therapy is a strategy under development to replace the impaired myocardium for recovery after heart injury. RECENT FINDINGS: Many studies have provided evidence of the beneficial effects of pluripotent stem cell-derived cardiomyocyte (CM) implantation into diseased rodent hearts, but there are still many challenges and limitations to replicating the same effects in large animal models for preclinical validation. In this review, we summarize progress in the use of pluripotent stem cell-derived CMs in large animal models based on three key parameters: species selection, cell source, and delivery. Most importantly, we discuss the current limitations and challenges that need to be solved to advance this technology to the translational stage.

Shared decision making for anticoagulation reduces anxiety and improves adherence in patients with atrial fibrillation.

BACKGROUND: Treatment with oral anticoagulants (OACs) could prevent stroke in atrial fibrillation (AF), but side effects developed due to OACs may cause patients anxiety during decision making. This study aimed to investigate whether shared decision making (SDM) reduces anxiety and improves adherence to stroke prevention measures in patients with AF. METHODS: A one-group pretest-posttest design using a questionnaire survey was applied at the outpatient cardiology clinic between July 2019 until September 2020. A Patient Decision Aid (PDA) tool was used for the completion of the questionnaire survey after health education and counseling. Ten questions were included for patients' recognition of SDM, and a 5-point scoring method was used, where "very much" was scored as 5 points, and "totally not" was scored as 1 point. RESULTS: Fifty-two patients with AF were enrolled. In terms of patients' recognition of SDM, points of more than 4.17 out of 5 were noted, indicating recognition above the level of "very much." The patients' anxiety scores before SDM were 3.56 (1.2), with a decrease of 0.64 points (p < 0.001) to 2.92 (1.3) after SDM. After SDM, the number of patients who decided to take OAC increased from 76.9% to 88.5%, and the 15.4% answering "unclear" decreased to 1.9% (p = 0.006). The patients' anxiety levels after SDM were associated with gender (p = 0.025). CONCLUSIONS: The approach using SDM enhanced our understanding of the pros and cons of OAC treatment and, in patients with AF, decreased anxiety about therapeutic decisions and increased willingness to accept treatment options.

The role of apoptosis in the pathogenesis of osteoarthritis.

PURPOSE: Apoptosis is an important physiological process, making a great difference to development and tissue homeostasis. Osteoarthritis (OA) is a chronic joint disease characterized by degeneration and destruction of articular cartilage and bone hyperplasia. This purpose of this study is to provide an updated review of the role of apoptosis in the pathogenesis of osteoarthritis. METHODS: A comprehensive review of the literature on osteoarthritis and apoptosis was performed, which mainly focused on the regulatory factors and signaling pathways associated with chondrocyte apoptosis in osteoarthritis and other pathogenic mechanisms involved in chondrocyte apoptosis. RESULTS: Inflammatory mediators such as reactive oxygen species (ROS), nitric oxide (NO), IL-1ß, tumor necrosis factor-α (TNF-α), and Fas are closely related to chondrocyte apoptosis. NF-κB signaling pathway, Wnt signaling pathway, and Notch signaling pathway activate proteins and gene targets that promote or inhibit the progression of osteoarthritis disease, including chondrocyte apoptosis and ECM degradation. Long non-coding RNAs (LncRNAs) and microRNAs (microRNAs) have gradually replaced single and localized research methods and become the main research approaches. In addition, the relationship between cellular senescence, autophagy, and apoptosis was also briefly explained. CONCLUSION: This review offers a better molecular delineation of apoptotic processes that may help in designing new therapeutic options for OA treatment.

Comparison of efficacy of pulmonary vein isolation between cryoballoon ablation and high-power short-duration ablation.

BACKGROUND: High-power short-duration (HPSD) and cryoballoon ablation (CBA) has been used for pulmonary vein isolation (PVI). OBJECTIVE: We aimed to compare the efficacy of PVI between CBA and HPSD ablation in patients with paroxysmal atrial fibrillation (PAF). METHODS: We retrospectively analyzed 251 consecutive PAF patients from January 2018 to July 2020. Of them, 124 patients (mean age 57.2 ± 10.1 year) received HPSD and 127 patients (mean age 59.6 ± 9.4 year) received CBA. In HPSD group, the radiofrequency energy was set as 50 W/10 s at anterior wall and 40 W/10 s at posterior wall. In CBA group, 28 mm s generation cryoballoon was used for PVI according the guidelines. RESULTS: There was no significant difference in baseline characteristics between these 2 groups. The time to achieve PVI was significantly shorter in cryoballoon ablation group than in HPSD group (20.6 ± 1.7 min vs 51.8 ± 36.3, P = 0.001). The 6-month overall recurrence for atrial tachyarrhythmias was not significantly different between the two groups (HPSD:14.50% vs CBA:11.0%, P = 0.40). There were different types of recurrent atrial tachyarrhythmia between these 2 groups. Recurrence as atrial flutter was significantly more common in CBA group compared to HPSD group (57.1% vs 12.5%, P = 0.04). CONCLUSION: In PAF patients, CBA and HPSD had a favourable and comparable outcome. The recurrence pattern was different between CBA and HPSD groups.

Application of Ensite™ LiveView function for identification of scar-related ventricular tachycardia isthmus.

INTRODUCTION: Dynamic display of real-time wavefront activation pattern may facilitate the recognition of reentrant circuits, particularly the diastolic path of ventricular tachycardia (VT). OBJECTIVE: We aimed to evaluate the feasibility of LiveView Dynamic Display for mapping the critical isthmus of scar-related reentrant VT. METHODS: Patients with mappable scar-related reentrant VT were selected. The characteristics of the underlying substrates and VT circuits were assessed using HD grid multielectrode catheter. The VT isthmuses were identified based on the activation map, entrainment, and ablation results. The accuracy of the LiveView findings in detecting potential VT isthmus was assessed. RESULTS: We studied 18 scar-related reentrant VTs in 10 patients (median age: 59.5 years, 100% male) including 6 and 4 patients with ischemic and nonischemic cardiomyopathy, respectively. The median VT cycle length was 426 ms (interquartile range: 386-466 ms). Among 590 regional mapping displays, 92.0% of the VT isthmus sites were identified by LiveView Dynamic Display. The accuracy of LiveView for isthmus identification was 84%, with positive and negative predictive values of 54.8% and 97.8%, respectively. The area with abnormal electrograms was negatively correlated with the accuracy of LiveView Dynamic Display (r = -.506, p = .027). The median time interval to identify a VT isthmus using LiveView was significantly shorter than that using conventional activation maps (50.5 [29.8-120] vs. 219 [157.5-400.8] s, p = .015). CONCLUSION: This study demonstrated the feasibility of LiveView Dynamic Display in identifying the critical isthmus of scar-related VT with modest accuracy.

Catheter Ablation in Arrhythmic Cardiac Diseases: Endocardial and Epicardial Ablation.

Arrhythmogenic cardiomyopathy (ACM) is a group of arrhythmogenic disorders of the myocardium that are not caused by ischemic, hypertensive, or valvular heart disease. The clinical manifestations of ACMs may overlap those of dilated cardiomyopathy, complicating the differential diagnosis. In several ACMs, ventricular tachycardia (VT) has been observed at an early stage, regardless of the severity of the disease. Therefore, preventing recurrences of VT can be a clinical challenge. There is a wide range of efficacy and side effects associated with the use of antiarrhythmic drugs (AADs) in the treatment of VT. In addition to AADs, patients with ACM and ventricular tachyarrhythmias may benefit from catheter ablation, especially if they are drug-refractory. The differences in pathogenesis between the various types of ACMs can lead to heterogeneous distributions of arrhythmogenic substrates, non-uniform ablation strategies, and distinct ablation outcomes. Ablation has been documented to be effective in eliminating ventricular tachyarrhythmias in arrhythmogenic right ventricular dysplasia (ARVC), sarcoidosis, Chagas cardiomyopathy, and Brugada syndrome (BrS). As an entity that is rare in nature, ablation for ventricular tachycardia in certain forms of ACM may only be reported through case reports, such as amyloidosis and left ventricular noncompaction. Several types of ACMs, including ARVC, sarcoidosis, Chagas cardiomyopathy, BrS, and left ventricular noncompaction, may exhibit diseased substrates within or adjacent to the epicardium that may be accountable for ventricular arrhythmogenesis. As a result, combining endocardial and epicardial ablation is of clinical importance for successful ablation. The purpose of this article is to provide a comprehensive overview of the substrate characteristics, ablation strategies, and ablation outcomes of various types of ACMs using endocardial and epicardial approaches.

Long-term mortality and cardiovascular outcomes in patients with atrial flutter after catheter ablation.

AIMS: For patients with typical and atypical atrial flutter (AFL) but without history of atrial fibrillation (AF), the long-term cardiovascular (CV) outcomes after catheter ablation for AFL remain unclear. We compared the long-term all-cause mortality and CV outcomes in patients with AFL receiving catheter ablation compared with the results with medical therapy. METHODS AND RESULTS: Atrial flutter patients receiving catheter ablation for typical AFL were identified using the Health Insurance Database, and constituted the 'AFL ablation group'. Patients with typical and atypical AFL but without ablation (AFL without ablation group) were propensity matched to the AFL ablation group. Patients with prior AF diagnosis were excluded. Primary outcomes included all-cause and CV mortality, heart failure (HF) hospitalization, and stroke. The multivariable cox hazards regression model was used to evaluate the hazard ratio (HR) for study outcomes. A total of 3784 AFL patients (1892 patients in each group) was studied. Their mean follow-up durations were 7.85 ± 2.57 years (AFL without ablation group) and 8.31 ± 4.53 years (AFL ablation group). Atrial flutter with ablation patients had lower risks of all-cause mortality (HR: 0.68, P < 0.001), CV deaths (HR: 0.78, P = 0.001), HF hospitalization (HR: 0.84, P = 0.01), and stroke (HR: 0.80, P = 0.01). CONCLUSIONS: Catheter ablation for AFL in patients without prior AF was associated with lower risks of all-cause mortality and CV events compared with AFL patients without ablation during long-term follow-ups.

10-Year Outcomes of Patients With Non-Paroxysmal Atrial Fibrillation Undergoing Catheter Ablation.

BACKGROUND: Radiofrequency catheter ablation (RFCA) is commonly performed in patients with non-paroxysmal atrial fibrillation (AF), but because very long-term follow-up results of RFCA are limited, we investigated the 10-year RFCA outcomes of non-paroxysmal AF.Methods and Results: We retrospectively enrolled 100 patients (89 men, mean age 53.5±8.4years) with drug-refractory symptomatic non-paroxysmal AF who underwent 3D electroanatomic-guided RFCA. Procedural characteristics at index procedures and clinical outcomes were investigated. In the index procedures, all patients had pulmonary vein isolation, 56 (56.0%), 48 (48.0%), and 32 (32.0%) underwent additional linear, complex fractionated atrial electrogram (CFAE) and non-pulmonary vein (NPV) foci ablations, respectively. After 124.1±31.7 months, 16 (16%) patients remained in sinus rhythm after just 1 procedure (3 with antiarrhythmic drugs [AAD]) and after multiple (2.1±1.3) procedures in 53 (53.0%) patients (22 with AAD). Left atrial (LA) diameter (hazard ratio HR 1.061; 95% confidence interval (CI) 1.020 to 1.103; P=0.003), presence of NPV triggers (HR 1.634; 95% CI 1.019 to 2.623; P=0.042) and undergoing CFAE ablation (HR 2.003; 95% CI 1.262 to 3.180; P=0.003) in the index procedure were independent predictors for recurrent atrial tachyarrhythmia. CONCLUSIONS: The 10-year outcomes of single RFCA in non-paroxysmal AF were unsatisfactory. Enlarged LA, presence of NPV triggers, and undergoing CFAE ablation in the index procedure independently predicted single-procedure recurrence. Multiple procedures are required to achieve adequate rhythm control.

Exercise Test for Patients with Long QT Syndrome.

Congenital long QT syndrome (LQTS) causes life-threatening cardiac arrhythmias and is the leading cause of sudden cardiac death in young people. Measurements of QT prolongation during exercise or postural change have been recommended to assist in the diagnosis of LQTS, particularly in those with hidden phenotypes. However, most evidence has come from single-center studies without external validation in an independent cohort. Inter-study heterogeneity leads to significant difficulties in interpreting and applying consistent diagnostic criteria for LQTS. A comprehensive systematic review is critically needed to summarize the evidence and validate the diagnostic performance of QT intervals during exercise or postural change across a variety of studies. In this study, we review cross-sectional and cohort studies evaluating the efficacy and feasibility of exercise tests or postural changes in diagnosing LQTS, and propose possible problems resulting from exercise tests.