Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Atrial fibrillation is common. Cardioversion to restore sinus rhythm is successful in over 90% of cases, but reversion to atrial fibrillation within a year occurs in the majority. Although predictors of maintenance of sinus rhythm following cardioversion have been described, to our knowledge no study has looked specifically at the population of patients undergoing first elective cardioversion for atrial fibrillation. Purpose We aimed to examine the demographic, clinical, and echocardiographic parameters that predict the maintenance of sinus rhythm to one year following first elective cardioversion, with the goal of generating a prediction tool to aid patient selection for the procedure. Methods Coding data was used to identify all patients who had undergone elective cardioversion at two centres in central New Zealand over a five-year period. Those with previous cardioversion were excluded. A range of demographic, clinical, and echocardiographic variables were collated, and univariate followed by multivariate analysis conducted to identify predictors of maintained sinus rhythm at one year, evidenced by documented recurrence of arrhythmia in the clinical record. Results 287 patients underwent first elective cardioversion across both sites, restoring sinus rhythm in 86% with 39% in sinus rhythm at one year. Atrial flutter (66 patients) had higher rates of successful cardioversion (96%), and maintained sinus rhythm (64%) than atrial fibrillation (83% and 32%), whilst cardioversion in one centre (52% vs. 31%) and the absence of paroxysmal symptoms (41% vs. 26%) were both associated with higher likelihood of maintained sinus rhythm at one year. Only the presence of atrial flutter (OR 1.34, P<0.001), and cardioversion in one of the centres (OR 1.19, P=0.002) increased the odds of maintained sinus rhythm at one year in multivariate analysis. A range of other demographic (age, gender, BMI), clinical (duration of symptoms, antiarrhythmics, renal function), and echocardiographic (left atrial volume, left ventricular ejection fraction, mitral valve dysfunction) variables failed to predict restoration and maintenance of sinus rhythm. Conclusion In patients undergoing first elective cardioversion, the presence of atrial flutter and site of cardioversion both predict maintained sinus rhythm at one year. A range of other demographic, clinical, and echocardiographic variables shown elsewhere to predict sinus rhythm after cardioversion fail to do so in this study. This negative outcome likely reflects low numbers of patients in sinus rhythm at one year following first cardioversion, significant population heterogeneity, and small effect size of contributor variables. Overcoming this would require a substantially larger dataset, something that could be overcome through the use of a national dataset for patients undergoing cardioversion.

BACKGROUND The risk of heart block during radiofrequency ablation of atrioventricular (AV) nodal reentrant tachycardia and septal accessory pathways is minimized by rapidly ceasing ablation in response to markers of risk, such as atrioventricular dissociation, fast junctional rhythm, PR interval prolongation, or 2 consecutive atrial or ventricular depolarizations. Currently this is done manually. OBJECTIVES The objectives of this study were to build and test a control system able to monitor cardiac rhythm and automatically terminate ablation energy when required. METHODS The device was built from off-shelf componentry. Preclinical testing involved real-time input of electrogram/electrocardiogram data from 209 ablation procedures (20 patients) over slow (n = 19) and fast (n = 1) AV nodal pathways. The device response speed was compared with the human response speed. The device's ability to prevent heart block was tested in 5 sheep. First-inhuman testing was then performed in 12 patients undergoing AV nodal reentrant tachycardia ablation. RESULTS Risk conditions necessitating shutoff of ablation (200 total; 111 predinical and 89 first-in-human) were detected by the device with 100% sensitivity and 94% specificity, automatically terminating ablation while still allowing successful ablation in all patients. Device shutoff of ablation was always faster than human response (median difference 1.24 seconds). In each of 5 sheep, 40 consecutive attempts to cause heart block by ablating over the His bundle were unsuccessful because of automatic shutoff in response to rhythm change. CONCLUSION Automated shutoff of ablation dose to the AV node in response to markers of the risk of heart block is feasible with high accuracy as well as faster response than human response. The system may improve the safety of ablation near the AV node by preventing heart block.

This month's highlights from the subspecialty journals over the past month span several important topics in cardiovascular medicine.The experience with a first-in-human radiofrequency ablation catheter with a camera is described in Circulation: Arrhythmia and Electrophysiology.In Circulation: Genomic and Precision Medicine, a clinical and genetic risk model for atrial fibrillation is described.A large observational registry suggests that revascularization of severe ischemia by stress cardiac magnetic resonance imaging is associated with greater survival in Circulation: Cardiovascular Imaging.Outcomes associated with intravascular ultrasound-guided left main revascularization are reported in Circulation: Cardiovascular Interventions.Performance metrics for machine-learning models are assessed in Circulation: Cardiovascular Quality and Outcomes.Last, the impact of remote visits on management of heart failure during the COVID pandemic is reported in Circulation: Heart Failure.

Background: Activated Clotting Time (ACT) guided heparinization is the gold standard for titrating unfractionated heparin (UFH) administration during atrial fibrillation (AF) ablation procedures. The current ACT target (300 s) is based on studies in patients receiving a vitamin K antagonist (VKA). Several studies have shown that in patients receiving Direct Oral Anticoagulants (DOACs), the correlation between ACT values and UFH delivered dose is weak. Objective: To assess the relationship between ACT and real heparin anticoagulant effect measured by anti-Xa activity in patients receiving different anticoagulant treatments. Methods: Patients referred for AF catheter ablation in our centre were prospectively included depending on their anticoagulant type. Results: 113 patients were included, receiving rivaroxaban (n = 30), apixaban (n = 30), dabigatran (n = 30), and VKA (n = 23). To meet target ACT, a higher UFH dose was required in DOAC than VKA patients (14,077.8 IU vs. 9565.2 IU, p < 0.001), leading to a longer time to achieve target ACT (46.5 min vs. 27.3 min, p = 0.001). The correlation of ACT and anti-Xa activity was tighter in the VKA group (Spearman correlation ρ = 0.53), compared to the DOAC group (ρ = 0.19). Despite lower ACT values in the DOAC group, this group demonstrated a higher mean anti-Xa activity compared to the VKA group (1.56 ± 0.39 vs. 1.14 ± 0.36; p = 0.002). Conclusion: Use of a conventional ACT threshold at 300 s during AF ablation procedures leads to a significant increase in UFH administration in patients treated with DOACs. This increase corresponds more likely to an overdosing than a real increase in UFH requirement.

Laser balloon (LB) has emerged as an interesting strategy for pulmonary vein isolation in paroxysmal atrial fibrillation (AF). A third-generation LB has recently been developed, allowing a continuous ablation set. We aimed to compare the results from our center’s experience with second and third-generation LBs to a cohort of matched patients who had undergone radiofrequency ablation (RFA) with contact-force catheters. This retrospective monocenter case-control study included our first 50 LB paroxysmal AF ablations (26 second and 24 third-generation LB) and 50 RFA controls, matched on age, sex and left atrial dilation. The two groups had similar baseline parameters. LB procedures were significantly shorter than RFA (129 (110–160) vs. 160 (119–198) min, p = 0.007). During AF ablation, two major complications occurred in each group. At the one-year follow-up, AF recurrence was diagnosed in 7 (14%) of the LB group vs. 14 (28%) of the RFA group (p = 0.14). Moreover, we observed that third-generation LB procedures were associated with shorter laser applications (22 (19–29) vs. 69 (55–76) min, p < 0.001) and procedural durations (111 (100–128) vs. 151.5 (128.5–167) min, p < 0.001) compared to second-generation LB procedures. In the context of the major increase in the number of AF ablations, LB demonstrated consistent results in terms of clinical success, complications and also reduced procedure durations compared to RFA.

Background: A multielectrode saline-irrigated radiofrequency (RF) balloon catheter with an integrated camera system was designed to perform single-shot pulmonary vein (PV) isolation. To optimize ablation, simultaneous circumferential RF energy can be delivered, albeit with power output that is tailored to individual electrodes based on direct visualization of tissue-electrode contact. In a first-in-human multicenter clinical trial, we studied the feasibility, performance, safety, and efficacy of PV isolation using this novel ablation catheter to treat atrial fibrillation. Methods: AF-FICIENT-I was a prospective, 5-center, single-arm study. After transseptal puncture, the RF balloon was positioned over the wire at each pulmonary (PV) ostium using a 13.3F sheath. RF energy was titrated based on visual contact (6–10 W; up to 60 seconds per ablation). Electrical PV isolation was confirmed using either, (1) sensing mini-electrodes situated on the RF balloon itself or (2) a circular mapping catheter. Patients were clinically assessed for recurrent atrial arrhythmias lasting >30 s over 12 months, after a 3-month blanking period. Results: Six operators performed de novo PV isolation in 99 patients (95 paroxysmal/4 persistent; age, 58±11; men, 67.7%). Median times, including procedure, fluoroscopy, ablation (time from first RF to last RF application), and balloon (time elapsing between catheter introduction to removal from the body) times, were 85 (interquartile range, 62–118), 14 (interquartile range, 9–23), 31 (interquartile range, 20–53), and 43 minutes (interquartile range, 32–70), respectively. The 12-month Kaplan-Meier estimates of freedom from any atrial arrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) or atrial fibrillation alone were 77.5% (95% CI, 67.6%–84.7%) and 84.1% (95% CI, 74.9%–90.1%), respectively. There were no device-related serious adverse events. Conclusions: The novel RF balloon catheter allowed visually guided, directional titration of ablative energy to safely isolate PVs with short procedure times. Registration: URL: https://www.anzctr.org.au ; Unique identifier: ACTRN12615001340527.

OBJECTIVES The aim of this study was to assess the long-term efficacy and outcomes of retrograde venous ethanol ablation in treating ventricular arrhythmias (VAs). BACKGROUND Retrograde coronary venous ethanol ablation (RCVEA) can be effective for radiofrequency ablation (RFA)-refractory VAs, particularly those arising in the LV summit (LVS). METHODS Patients with drug and RFA-refractory VAs were considered for RCVEA after RF failure attempts. Intramural coronary veins (tributaries of the great cardiac, anterior interventricutar, lateral cardiac, posterotaterat, and middle cardiac) were mapped using an angioplasty wire. Ethanol infusion was delivered in veins with appropriate signals. RESULTS Of 63 patients (age 63 +/- 14 years; 60% men) with VAs (71% extrasystote, 29% ventricular tachycardia, 76% LVS origin), RCVEA was performed in 56 patients who had suitable vein branches. These were defined as those amenable to cannulation and with intramural signals that preceded those mapped in the epicardium or endocardium and had better matching pace maps or entrainment responses. Seven patients had no suitable veins and underwent RFA. In 38 of 56 (68%) patients, the VAs were successfully terminated exclusively with ethanol infusion. In 17 of 56 (30%) patients, successful ablation was achieved using ethanol with adjunctive RFA in the vicinity of the infused vein due to acute recurrence or ethanol-induced change in VA morphology. Overall, isolated or adjuvant RCVEA was successful in 55 of 56 (98%) patients. At 1-year follow-up, 77% of patients were free of recurrent arrhythmias. Procedural complications included 2 venous dissections that led to pericardial effusions. CONCLUSIONS RCVEA offers a significant tong-term effective treatment for patients with drug and RF-refractory VAs. (C) 2020 by the American College of Cardiology Foundation.

OBJECTIVES This study systematically evaluated mechanisms of atrial tachycardia (AT) by using ultra-high-resolution mapping in a large cohort of patients. BACKGROUND An incomplete understanding of the mechanism of AT is a major determinant of ablation failure. METHODS Consecutive patients with >= 1 AT (excluding cavotricuspid isthmus-dependent flutter) were included. Mapping was performed with a 64-pole mapping catheter. The AT mechanism was defined based on activation mapping and confirmed by entrainment in selected cases. RESULTS A total of 132 patients were included (60 +/- 12 years; 31 [23%] female; 111 [84%] previous atrial fibrillation [AF] ablation; 5 [4%] previous left atriotomy). One hundred four (94%) of the 111 post-AF ablation AT patients had substrate-based ablation during the index AF ablation. A total of 214 ATs were mapped, with complete definition of the AT mechanism in 206 (96%). A total of 129 (60%) had anatomic macro-re-entry (circuit diameter 44.2 +/- 9.6 mm), 57 (27%) had scar-related localized re-entry (circuit diameter 25.8 +/- 12.2 mm), and 20 (9%) had focal AT. Fifty-eight (45%) patients had multiple ATs (27 [20%] dual-loop re-entry; 60 [43%] sequential AT) with complex and highly variable transitions between AT circuits. A total of 116 (90%) of 129 macro-re-entrant ATs, 56 (98%) of 57 localized AT, and 20 (100%) of 20 focal ATs terminated after radiofrequency ablation. After a mean follow-up of 13 +/- 9 months, 57 (46%) patients experienced recurrence of AT. CONCLUSIONS Among patients with AT in the context of previous atrial interventions, particularly post-AF ablation patients, multiple complex AT circuits are common. Despite complete delineation of arrhythmia circuits using ultra-high-resolution mapping and high acute ablation success rates, long-term freedom from AT is modest. (C) 2020 by the American College of Cardiology Foundation.

Aims Our study assesses the value of electrograms (EGMs) characteristics to identify a ventricular tachycardia (VT) isthmus entrance in patients with post-infarct VT. Post-infarct VTs are mostly due to a re-entrant circuit. A pacemapping (PM) approach is able to localize the VT isthmus during sinus rhythm. Limited data are available about the role of local EGMs in defining VT isthmus location. Methods and results Twenty consecutive patients (70% male) referred for post-infarct VT catheter ablation were included in the present study. The VT isthmus was defined according to the PM method. At each recording site, 10 characteristics of the local EGM were assessed to predict the location of the VT isthmus entrance. In total, 924 EGMs were acquired, of which 127 were located in the VT isthmus entrance. Logistic regression analysis showed that bipolar voltage, number of EGM positive peaks, and sQRS interval were independently associated with VT isthmus entrance location. The ROC curve best fitted the model at the cut-off 0.1641 (sensitivity 72%, specificity 75.2%, positive predictive value 31.3%, negative predictive value 94.4%, area under the curve 0.78, P < 0.001). Based upon these results, we developed an algorithm implemented in an automatic calculator to determine the likelihood that an EGM is located at a VT isthmus entrance. Conclusion Our study suggests that three EGM characteristics: bipolar voltage, number of positive peaks, and sQRS interval can successfully identify a VT isthmus entrance in post-infarct patients.

Atrial tachyarrhymia is a frequent complication after mitral valve surgery. Atrial incisions can create re-entry pathways around anatomic and surgically created obstacles. We describe the long term incidence and type of atrial arrhythmias after mitral valve replacement (MVR). We collected 10 years of patients who went MVR in a tertiary center from the local region. Records were reviewed for incident atrial tachyarrhythmia during follow-up after a three month blanking period. A total of 245 patients were identified who underwent MVR. Persistent atrial fibrillation (AF) was present in 98 patients pre operatively, 97 of these remained in AF long term, one had a maze procedure and achieved sinus rhythm. Post operative incisional atrial flutter and atrial tachycardia each occurred in one patient. 109 had no pre-existing atrial arrhythmia. Of these 27 had incident atrial tachyarrhythmia (20 atrial fibrillation, 7 atrial flutter) over an average follow-up of 42 months. A Kaplan-Meier curve was constructed showing freedom from incident arrhythmia 91% at one year and 83% at 5 years. Freedom from permanent arrhythmia was 94% and 87% respectively. Six of the seven patients with atrial flutter had electrocardiograms potentially consistent with incisional flutter, all of these had their MVR performed via right atrial incision. One of these patients was formally identified as incisional flutter and went on to have a successful ablation. Atrial tachyarrhythmia occurs commonly after MVR. Incisional flutter may be under-recognized and type of incision may influence arrhythmia outcomes. Further research is needed.

Ventricular tachycardia commonly involves intramural reentry circuits that can also give rise to ventricular fibrillation. Identification of these channels is key to their effective ablation, but the capacity to map intramural pathways and substrate directly is limited. This chapter reviews experimental methods that have been used to reconstruct three-dimensional electrical activity across the ventricular wall in normal and diseased hearts and provides a critical analysis of resultant findings. Intramural extracellular mapping has provided important insights into the effects of ventricular myocyte architecture on normal activation spread. While extracellular mapping has provided extremely valuable information about intramural activation, it has proved much more difficult to characterize repolarization using this approach. Intramural access is the main constraint on recording intracellular potentials and optical mapping. The chapter briefly considers how the ventricular wedge preparation has been used to address this problem and then summarizes optical methods for recording intramural electrical activity in the intact ventricular wall.

Endocardial access to the left ventricle (LV) for catheter ablation of ventricular tachycardia is challenging when mechanical aortic and mitral valves are present. A case of ventricular transseptal access to the LV has been reported in this setting [(1)][1]. This image reviews such an approach, with

Background: Ventricular tachycardia (VT) can be difficult to manage medically and radiofrequency ablation can improve symptoms, cardiac function and mortality. It can also reduce device therapy and reliance on potentially toxic anti-arrhythmic medications. It can be undertaken for both structural and idiopathic VT. Method: We retrospectively reviewed patients who underwent VT ablation at Wellington Regional Hospital over a 3-year period from December 2014. Results: Sixty-three procedures were performed on 51 patients with the following characteristics:Tabled 1n (%)Average age (y)60Male sex38 (75)Aetiology Structural31 (61) Idiopathic20 (39)Severely impaired left ventricular function15 (29)Implantable cardioverter defibrillator in situ22 (43)Symptoms Palpitations49 (96) Syncope18 (35) Cardiac arrest13 (25)Medications Beta blockers41 (80) Calcium channel blocker9 (18) Amiodarone19 (37) Class 1 antiarrhythmic drugs10 (20) Emergent/acute14 (27) General anaesthesia2 (4) Open table in a new tab The primary operator considered the procedure acutely successful in 45 patients (69%). Eight required multiple procedures to achieve this outcome. According to arrhythmia burden on Holter monitor or implantable device at follow-up, 18 (30%) had complete abolition and 18 (30%) partial improvement/modification. Thirty-eight patients (75%) reported symptomatic improvement and eight were able to stop amiodarone. Left ventricular ejection fraction improved in four patients. There were very few complications, with two femoral haematomas, one femoral pseudoaneurysm, and two pericardial effusions. All patients were alive at 30 days. Conclusion: Radiofrequency ablation for VT is a safe procedure with reasonably efficacy, providing a viable treatment option for many patients with difficult-to-manage arrhythmias.

A 73-year-old patient with an arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) was referred for ventricular tachycardia (VT) ablation. The procedure was performed with a combined endocardial and percutaneous epicardial approach, using the CARTO3 mapping system. After the clinical

We report a case of recurrent focal atrial tachycardia (AT) which mechanisms could be resolved by using noninvasive electrocardiographic imaging (ECGI) reconstructing epicardial potentials and rapid high‐density endocardial contact mapping (Rhythmia™, Boston Scientific, Natick, MA, USA). ECGI demonstrated focal activity from the anterior of the left superior pulmonary vein antrum, although Rhythmia™ showed focal activity from the high anterior left atrium with the 2 nd focus originating from the site where identical to the focus on the ECGI map with slightly delay (by 8 ms). Elimination of the AT by radiofrequency applications for both of the endocardial focuses indicated the dual endocardial exits from an epicardial focus.

AF is a heterogeneous rhythm disorder that is related to a wide spectrum of etiologies and has broad clinical presentations. Mechanisms underlying AF are complex and remain incompletely understood despite extensive research. They associate interactions between triggers, substrate and modulators including ionic and anatomic remodeling, genetic predisposition and neuro-humoral contributors. The pulmonary veins play a key role in the pathogenesis of AF and their isolation is associated to high rates of AF freedom in patients with paroxysmal AF. However, ablation of persistent AF remains less effective, mainly limited by the difficulty to identify the sources sustaining AF. Many theories were advanced to explain the perpetuation of this form of AF, ranging from a single localized focal and reentrant source to diffuse bi-atrial multiple wavelets. Translating these mechanisms to the clinical practice remains challenging and limited by the spatio-temporal resolution of the mapping techniques. AF is driven by focal or reentrant activities that are initially clustered in a relatively limited atrial surface then disseminate everywhere in both atria. Evidence for structural remodeling, mainly represented by atrial fibrosis suggests that reentrant activities using anatomical substrate are the key mechanism sustaining AF. These reentries can be endocardial, epicardial and intramural which makes them less accessible for mapping and for ablation. Subsequently, early interventions before irreversible remodeling are of major importance. Circumferential pulmonary vein isolation remains the cornerstone of the treatment of AF, regardless of the AF form and of the AF duration. No ablation strategy consistently demonstrated superiority to pulmonary vein isolation in preventing long term recurrences of atrial arrhythmias. Further research that allows accurate identification of the mechanisms underlying AF and efficient ablation should improve the results of PsAF ablation.