Electrogram-guided Endomyocardial Biopsy Yield in Patients with Suspected Cardiac SarcoidosisAbbas Hoteit MD, Marwan M. Refaat, MDDivision of Cardiology, Department of Internal Medicine, American University of Beirut Medical Center, Beirut, LebanonRunning Title: Electrogram-guided Biopsy in Cardiac SarcoidosisWords: 819 (excluding the title page and references)Keywords: Cardiac Sarcoidosis, Heart Diseases, Cardiovascular Diseases, Cardiac ArrhythmiasFunding: NoneDisclosures: NoneCorresponding Author:Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FAAMAAssociate Professor of MedicineDirector, Cardiovascular Fellowship ProgramDepartment of Internal Medicine, Cardiovascular Medicine/Cardiac ElectrophysiologyDepartment of Biochemistry and Molecular GeneticsAmerican University of Beirut Faculty of Medicine and Medical CenterPO Box 11-0236, Riad El-Solh 1107 2020- Beirut, LebanonUS Address: 3 Dag Hammarskjold Plaza, 8th Floor, New York, NY 10017, USAOffice: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct)Sarcoidosis is a multisystem disease that is characterized by T-cell mediated formation of noncaseating granulomas in affected organs. The disease commonly might involve hilar lymphadenopathy, lungs, liver, spleen, heart, and other organs. The natural course and prognosis of the disease generally depends on the extent of the disease and the organs affected where spontaneous remission occurs in around two-thirds of patient.1 Involvement of the heart is recognized in around 30% of patients and is associated with poor prognosis.2 The presentation of patients with cardiac sarcoidosis varies significantly; it can range from mild to severe disease such as heart failure and fatal arrhythmias. Patients with cardiomyopathies might require implantable cardiac defibrillators or cardiac resynchronization therapy for sudden death prevention.3,4 Cardiac sarcoidosis can either present alongside extracardiac manifestations or isolated.5Diagnosis of cardiac sarcoidosis presents a particular challenge since there is no gold standard diagnostic tool and the presentation is variable.6 There are no disease-specific biomarkers that can reliably be used for diagnosis. Clinicians typically rely on current published guidelines for diagnostic criteria of cardiac sarcoidosis such as those of Heart Rhythm Society (HRS) and the Japanese Ministry of Health and Welfare (JMHW). The revised JMHW criteria provide a diagnosis either through histological evidence on biopsy or through the fulfillment of major and minor criteria that do not include cardiac PET whereas the HRS criteria provide either a definite pathway for diagnosis through histology or a clinical pathway for diagnosis of probable cardiac sarcoidosis that includes both cardiac PET and CMR as criteria.7,8 A definitive diagnosis of cardiac sarcoidosis can be obtained if endomyocardial biopsy can show noncaseating granulomas in the context of suspected cardiac sarcoidosis and other granulomatous diseases are excluded. However, endomyocardial biopsy has a low sensitivity of 20-30% since it is limited by several factors such as technique, sampling, patchy distribution of granulomas, location of lesions, and stage of the disease at the time of biopsy.5 Areas of inflammation and scarring typically show abnormal electrogram morphology, hence, it is thought that electrogram guidance may help in increasing the yield of endomyocardial biopsies. Electrogram guidance would potentially help avoiding normal myocardium during biopsy leading to increased yield and sensitivity.9In their study, Ezzedine et al. assessed the diagnostic yield of electrogram-guided endomyocardial biopsy and investigated association between positive endomyocardial biopsy and prognosis in patients with suspected cardiac sarcoidosis.10 This retrospective observational study included seventy-nine patients between 2011 and 2019 who had suspected cardiac sarcoidosis based on clinical presentation and findings on late gadolinium-enhancement cardiac magnetic resonance and/or cardiac positron emission tomography-computed tomography with N-13 NH3 perfusion imaging and F-18 fluorodeoxyglucose. Biopsy was done in patients suspicious of cardiac sarcoidosis in patients without extracardiac sarcoidosis or those with extracardiac disease but atypical/equivocal findings of cardiac sarcoidosis on imaging and meeting criteria in HRS guidelines as per the routine practice in Mayo Clinic. Mapping of the heart was performed prior to biopsy with partial guidance based on pre-procedural cardiac imaging. In patients with no identifiable abnormalities on electrogram, biopsies were taken from areas corresponding to those with abnormalities on pre-procedural imaging. Collected specimens were processed according to protocol and assessed by a blinded specialist. These specimens were considered positive if there was a combination of non-necrotizing granulomas, interstitial fibrosis, and scatted eosinophils. The study showed that electrogram-guided endomyocardial biopsy was associated with an adequate negative predictive value but low positive predictive value. A diagnosis of probable cardiac sarcoidosis can be made in patients with extracardiac manifestations according to established guidelines whereas in patients with suspected isolated cardiac sarcoidosis this is more difficult and as such biopsies play a more major role here. This study showed that, when guided by electrograms, endomyocardial biopsies had a higher diagnostic yield (41%) than that established in literature around 20-25%. Utilizing both abnormalities seen on both electrograms and on CMR or PET showed the highest diagnostic yield in endomyocardial biopsies. This acts as an important point of consideration for further research because accurate and timely diagnosis is paramount due to the diagnostics challenges and poor prognosis seen in cardiac sarcoidosis.10Previous evidence had shown that a positive endomyocardial biopsy for sarcoidosis was associated with poor prognosis.11However, LVAD and transplantation-free survival was found to be similar regardless of status of endomyocardial biopsy in this study.10 The authors explained that this could be explained by earlier detection of disease, differences in treatment, or more subtle detection of areas of involvement through electrograms. This study was well conducted but has been limited by its nature of being a retrospective observational study. Also, mapping was mostly limited to the right ventricle which may have underestimated the diagnostic yield of biopsies. This study represents the management done in a single tertiary care center which may not represent the same practice in other institutions with different facilities. Further multicenter and prospective studies are warranted to corroborate the data here and assess diagnostic and therapeutic modalities and long-term outcomes in patients.ReferencesStatement on sarcoidosis. Joint Statement of the American Thoracic Society (ATS), the European Respiratory Society (ERS) and the World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) adopted by the ATS Board of Directors and by the ERS Executive Committee, February 1999. Am J Respir Crit Care Med Aug 1999 ;160(2):736-55.Sekhri V, Sanal S, Delorenzo LJ, Aronow WS, Maguire GP. Cardiac sarcoidosis: a comprehensive review. Arch Med Sci Aug 2011; 7(4):546-54.AlJaroudi WA, Refaat MM, Habib RH, Al-Shaar L, Singh M, Gutmann R, Bloom HL, Dudley SC, Ellinor PT, Saba SF, Shalaby AA, Weiss R, McNamara DM, Halder I, London B; for the Genetic Risk Assessment of Defibrillator Events (GRADE) Investigators. Effect of Angiotensin Converting Enzyme Inhibitors and Receptor Blockers on Appropriate Implantable Cardiac Defibrillator Shock: Insights from the GRADE Multicenter Registry. Am J Cardiol Apr 2015; 115 (7): 115(7):924-31.Refaat M, Mansour M, Singh JP, Ruskin JN, Heist EK: Electrocardiographic Characteristics in Right Ventricular Versus Biventricular Pacing in Patients With Paced Right Bundle Branch Block QRS Pattern. J Electrocardiol Mar-Apr 2011; 44 (2): 289-95.Isobe M, Tezuka D. Isolated cardiac sarcoidosis: Clinical characteristics, diagnosis and treatment. Int J Cardiol Mar 2015; 182:132-40.Ahmed AI, Abebe AT, Han Y, Alnabelsi T, Agrawal T, Kassi M, Aljizeeri A, Taylor A, Tleyjeh IM, Al-Mallah MH. The prognostic role of cardiac positron emission tomography imaging in patients with sarcoidosis: A systematic review. J Nucl Cardiol Jul 2021; doi: 10.1007/s12350-021-02681-z. Online ahead of print.Sharma A, Okada DR, Yacoub H, Chrispin J, Bokhari S. Diagnosis of cardiac sarcoidosis: an era of paradigm shift. Ann Nucl Med Feb 2020;34(2):87-93.Ha FJ, Agarwal S, Tweed K, Palmer SC, Adams HS, Thillai M, Williams L. Imaging in Suspected Cardiac Sarcoidosis: A Diagnostic Challenge. Curr Cardiol Rev 2020;16(2):90-97.Liang JJ, Hebl VB, DeSimone CV, Madhavan M, Nanda S, Kapa S, Maleszewski JJ, Edwards WD, Reeder G, Cooper LT , Asirvatham SJ. Electrogram guidance: a method to increase the precision and diagnostic yield of endomyocardial biopsy for suspected cardiac sarcoidosis and myocarditis. JACC Heart Fail Oct 2014;2(5):466-73.Ezzedine FM, Kapa S, Rosenbaum A, Blauwet L, Deshmukh AJ, AbouEzzeddine OF, Maleszewski JJ, Asirvatham SJ, Bois JP, Schirger JA, Chareonthaitawee P, Siontis KC. Electrogram-guided Endomyocardial Biopsy Yield in Patients with Suspected Cardiac Sarcoidosis and Relation to Outcome. J Cardiovasc Electrophysiol Jul 2021; In Press.Ardehali H , Howard DL, Hariri A, Qasim A, Hare JM, Baughman KL, Kasper EK. A positive endomyocardial biopsy result for sarcoid is associated with poor prognosis in patients with initially unexplained cardiomyopathy. Am Heart J Sep 2005 ;150(3):459-63.

A document by Anthony Gebran. Click on the document to view its contents.

Introduction. During left bundle branch area pacing (LBBAP) lead implantation, intermittent monitoring of unipolar pacing characteristics validates LBB capture and can detect septal perforation. We aimed to demonstrate that continuous uninterrupted unipolar pacing from an inserted lead stylet (LS) is feasible and facilitates LBBAP implantation. Methods. Thirty patients (mean age 76 ± 14 years) were implanted with stylet-driven pacing lead (Biotronik Solia S60). In 10 patients (validation-group) conventional, interrupted implantation was performed, with comparison of unipolar pacing characteristics between LS and connector-pin (CP)-pacing after each rotation step. In 20 patients (feasibility-group) performance and safety of uninterrupted implantation during continuous pacing from the LS were analyzed. Results. In the validation-group, LS and CP-pacing impedances were highly correlated (R2=0.95, p<0.0001, bias 12±37Ω). Pacing characteristics from LS and CP showed comparable sensed electrograms and paced QRS morphologies. In the feasibility-group, continuous LS-pacing allowed beat-to-beat monitoring of impedance and QRS morphology to guide implantation. This resulted in successful LBBAP in all patients, after a mean of 1±0 attempts, with mean threshold 0.81 ± 0.4V, median sensing 6.5mV [IQR 4.4-9.5] and mean impedance 624 ± 101Ω, and positive LBBAP-criteria with median paced QRS duration 120ms [IQR 112-152ms] and median pLVAT 73ms [IQR 68-80.5ms]. No septal perforation occurred. Conclusion. Unipolar pacing from the LS allows accurate determination of pacing impedance and generates similar paced QRS morphologies and equal sensed electrograms, compared to CP pacing. Continuous LS pacing allows real-time monitoring of impedance and paced QRS morphology, which facilitates a safe and successful LBBAP lead implantation.

Enhanced detection of atrial arrhythmias by implantable monitors: Have we found what we are looking for?

Is There Rule to the Chaos: Defining Stable Patterns in Atrial Fibrillation

BACKGROUND. Myxomatous mitral valve prolapse (MVP) and mitral-annular disjunction (Barlow disease) are at-risk for ventricular arrhythmias (VA). Fibrosis involving the papillary muscles and/or the infero-basal left ventricular (LV) wall was reported at autopsy in sudden cardiac death (SCD) patients with MVP. METHODS AND RESULTS: Twenty-three patients with VA were enrolled, including five with syncope and four with a history of SCD. Electrophysiological parameters were correlated with VA patterns, ECG inferior negative T wave (nTW), and late gadolinium enhancement (LGE) assessed by cardiac magnetic resonance. Premature ventricular complex (PVC) burden was 12061.9±12994.6 /24 hours with a papillary-muscle type (PM-PVC) in 18 patients (68%). Twelve-lead ECG showed nTW in 12 patients (43.5%). A large Uni<8.3mV area (62.4+/- 45.5 cm2) was detected in the basal infero-lateral LV region in 12 (73%) patients, and in the papillary muscles (2.2+/-2.9 cm2) in 5 (30%) of 15 patients undergoing EAM. A concomitant Bi<1.5 mV area (5.0±1.0 cm2) was identified in 2 patients. A history of SCD, and the presence of nTW, and LGE were associated with a greater Uni<8.3mV extension: (32.8+/-3.1 cm2 vs. 9.2+/-8.7 cm2), nTW (20.1+/-11.0vs.4.1+/-3.8cm2), and LGE (19.2 ± 11.7 cm2 vs. 1.0 ± 2.0 cm2, p=0.013), respectively. All patients with PM-PVC had a Uni<8.3mV area. CONCLUSIONS: Low unipolar low voltage areas can be identified with EAM in the basal infero-lateral LV region and in the papillary muscles as a potential electrophysiological substrate for VA and SCD in patients with MVP and Barlow disease phenotype

Background: β-blockers are first-line therapy in patients with long QT syndrome (LQTS). However, β-blockers had genotype dependent efficacy (LQT1>LQT2>LQT3). Sodium channel blockers have been recommended as add-on therapy for LQT3 patients. However, the effect of sodium channel blockers in all LQT patients remains unknown. Methods: We conducted a systematic electronic search of PubMed, Embase and the Cochrane Library. Fixed effects model was used to assess the effect of sodium channel blockers on QTc, cardiac events (CEs), and the proportion of QTc≥500 ms and QTc≤460 ms in LQTS patients. Results: Pooled analysis of 14 studies with 213 LQTS patients showed that sodium channel blockers significantly shortened QTc by nearly 50 ms (MD -49.43, 95%CI -57.80 to -41.05, P<0.001), reduced the incidence of CEs (OR 0.12, 95%CI 0.04 to 0.32, P<0.001) and the proportion of QTc≥500 ms (OR 0.15, 95%CI 0.09 to 0.26, P<0.001), and increased the proportion of QTc≤460 ms (OR 18.00, 95%CI 7.49 to 43.26, P<0.001). Sodium channel blockers significantly shortened QTc both in LQT3 and non-LQT3 patients, while the QTc shortening effect in LQT3 was superior to that in non-LQT3 (57.39 ms vs. 36.61 ms). Mexiletine, flecainide, and ranolazine all significantly shortened QTc, and the QTc shortening effect by mexiletine was the best (60.70 ms vs. 49.08 ms vs. 50.10 ms). Conclusions: sodium channel blockers can be useful both in LQT3 and non-LQT3 patients. Mexiletine, flecainide and ranolazine significantly shortened QTc in LQTS patients, and the QTc shortening effect by mexiletine was the best.

Background and Objective: Ectopic beats originating from the pulmonary vein (PV) trigger atrial fibrillation (AF). The purpose of this study was to clarify the electrophysiological determinant of AF initiation from the PVs. Methods: Pacing studies were performed with a single extra stimulus mimicking an ectopic beat in the left superior pulmonary veins (LSPVs) in 62 patients undergoing AF ablation. Inducibility of AF, effective refractory period (ERP) and conduction properties within the PVs were analyzed. Results: A single extra stimulus in LSPV induced AF in 20 patients (32% of all patients) at the mean coupling interval (CI) of 172 ms. A CI-dependent anisotropic conduction at the AF onset was visualized in a 3D-mapping. Onset of AF was site-specific with reproducibility in each individual. Mean ERP in LSPV in the AF inducible group was shorter than that in the AF non-inducible group (182 ± 55 ms vs 254 ± 51 ms, P<0.0001). LSPV ERP dispersion was greater in the AF inducible group than in the AF non-inducible group (45 ± 28 ms vs 27 ± 19 ms, P<0.01). Circumferential intra-PV conduction time (IPVCT) exhibited decremental properties in response to shortening of CI, and the prolongation of IPVCT in the AF inducible site was greater than that in the AF non-inducible site (P<0.05) in each individual. Conclusions: Location and coupling interval of an ectopic excitation ultimately determine the initiation of AF from the PVs. ERP dispersion and circumferential conduction delay may lead to anisotropic conduction and reentry within the PVs that initiate AF.

Background: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation following MVS is limited.) CA can be challenging given perivalvular substrate in the setting of mitral annuloplasty or prosthetic valves. Objective: To investigate the characteristics, safety, and outcomes of radiofrequency catheter ablation (CA) in patients with prior mitral valve surgery (MVS) and ventricular arrhythmias (VA). Methods: We identified consecutive patients with prior MVS who underwent CA for VT or PVC between January 2013- December 2018. We investigated the mechanism of arrhythmia, ablation approach, peri-operative complications, and outcomes. Results: In our cohort of 31 patients (77% men, mean age 62.3±10.8 years, left ventricular ejection fraction 39.2±13.9%) with prior MVS underwent CA (16 VT; 15 PVC). Access to the left ventricle was via transseptal approach in 17 patients, and a retrograde aortic approach was used in 13 patients. A combined transseptal and retrograde aortic approach was used in one patient, and a percutaneous epicardial approach was combined with trans-septal approach in 1patient. Heterogenous scar regions were present in 94% of VT patients and scar-related reentry was the dominant mechanism of VT. Clinical VA substrates involved the peri-mitral area in 6 patients with VT and 5 patients with PVC ablation. No procedure-related complications were reported. The overall recurrence-free rate at 1-year was 72.2%; 67% in the VT group and 78% in the PVC group. No arrhythmia-related death was documented on long-term follow-up. Conclusion: CA of VAs can be performed safely and effectively in patients with MVS

Background: During non-selective His bundle (HB) pacing, it is clinically important to confirm His bundle capture vs. right ventricular septal (RVS) capture. The present study aimed to validate the hypothesis that during HB capture left ventricular lateral wall activation time, approximated by the V6 R-wave peak time (V6RWPT), will not be longer than the corresponding activation time during native conduction. Methods: Consecutive patients with permanent HB pacing were recruited; cases with abnormal His-ventricle interval or left bundle branch block were excluded. Two corresponding intervals were compared: stimulus-V6RWPT and native HBpotential-V6RWPT. Difference between these two intervals (delta V6RWPT), diagnostic of lack of HB capture, was identified using receiver operating characteristic (ROC) curve analysis. Results: A total of 723 ECGs (219 with native rhythm, 172 with selective HB, 215 with non-selective HB, and 117 with RVS capture) were obtained from 219 patients. The native HB-V6RWPT, non-selective-, and selective-HB paced V6RWPT were nearly equal, while RVS V6RWPT was 32.0 (±9.5) ms longer. The ROC curve analysis indicated delta V6RWPT > 12 ms as diagnostic of lack of HB capture (specificity of 99.1% and sensitivity of 100%). A blinded observer correctly diagnosed 96.7% (321/332) of ECGs using this criterion. Conclusions: We validated a novel criterion for HB capture that is based on the physiological left ventricular activation time as an individualized reference. HB capture can be diagnosed when paced V6RWPT does not exceed the value obtained during native conduction by more than 12 ms, while longer paced V6RWPT indicates RVS capture.

Impact of Pre-ablation Weight Loss on the Success of Catheter Ablation for Atrial FibrillationAbdul Hafiz Al Tannir BS, Marwan M. Refaat MDDepartment of Internal Medicine, Division of Cardiology, American University of Beirut Medical Center, Beirut, LebanonRunning Title: Pre-ablation Weight Loss and Success of AF AblationDisclosures: NoneFunding: NoneKeywords: Cardiac Arrhythmias, Cardiovascular Diseases, Heart Diseases, Weight Loss, Catheter Ablation, Atrial FibrillationWords: 621 (excluding references)Correspondence:Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FRCPAssociate Professor of MedicineDirector, Cardiovascular Fellowship ProgramDepartment of Internal Medicine, Cardiovascular Medicine/Cardiac ElectrophysiologyDepartment of Biochemistry and Molecular GeneticsAmerican University of Beirut Faculty of Medicine and Medical CenterPO Box 11-0236, Riad El-Solh 1107 2020- Beirut, LebanonFax: +961-1-370814Clinic: +961-1-759616 or +961-1-355500 or +961-1-350000/+961-1-374374 Extension 5800Office: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct)Email: [email protected] the United States, the prevalence of obese individuals has risen 3-fold since 1960, with 1 in every 3 persons being obese. The effect of weight changes on the progression on atrial fibrillation is well-established but the effect of pre-ablation weight loss on the recurrence of atrial fibrillation is not well-studied. Atrial fibrillation is the most frequently encountered cardiac arrhythmia [1]; it currently affects around 2.7 million people in the United States of America and is estimated that 6-12 million people will suffer from this condition by 2050 [2, 3]. Pulmonary vein isolation is the primary target for cardiac ablation; it can be achieved either by radiofrequency (RF) or cryoballoon ablation (CBA) [4, 5]. The FIRE and ICE trial conducted by Kuck et al showed that CBA therapy was associated with significantly fewer recurrence, rehospitalization, and cardioversion rates [6]. Several studies suggest the preferred use of CBA in treating atrial fibrillation in obese patients due to the increased surface area for ablation [4].Obesity has adverse effects on the structure and hemodynamics of the heart and it is a well-established risk factor for the development of atrial fibrillation [3]. A prospective cohort study performed by Pathak et al showed that progressive weight loss in obese and overweight patients resulted in dose-dependent effects on freedom from atrial fibrillation (FFAF) [7]. Similarly, Middeldrop et al, concluded that obesity is associated with the progression of the disease while weight loss is associated with reversal of the progression [8]. Limited data is available regarding the effect of weight loss on the recurrence of atrial fibrillation post-ablation. Current guidelines recommend lifestyle modifications, including a healthy diet and exercise, for overweight and obese patients before ablation [8, 9].The study of Peigh et al. is a retrospective cohort study from 2012-2017; 607 patients met the inclusion criteria. The aim of the study is to assess the impact of patient-directed weight loss 1 year before CBA on FFAP 15 months after ablation. The authors addressed an important topic that is poorly understood. Obese patients have a significantly lower FFAF rate 40-50% than the overall population 60-80%. The study selectively included patients undergoing CBA therapy. The follow-up time was 1-year post-ablation. The study concluded that, with the exception of non-obese patients with persistent atrial fibrillation, weight loss is associated with a significantly increased FFAF while weight gain led to a decrease in FFAF. A similar study assessed the impacted of physician-mediated risk control in patients undergoing RF ablation for atrial fibrillation [10]. A total of 149 patients were included in the prospective cohort study. The study showed a positive association between physician-directed weight loss (≥ 10%) and FFAF in symptomatic obese patients. The study performed by Peigh et al, included though a larger subject group (607) than LEGACY (141); however, the LEGACY is a prospective cohort study that is more suitable to monitor the fluctuation in patients’ variables before ablation.This study was well conducted but has the limitations of retrospective studies; a prospective cohort study would better monitor the variations in patients’ variables pre-ablation. In addition, as the authors stated, asymptomatic atrial fibrillation episodes may go unnoticed.Patients with atrial fibrillation, particularly those who are obese, should be advised to lose weight prior to catheter ablation. Lifestyle modifications should not be limited to patients undergoing ablation; the effect of weight loss on disease progression is well-established. Due to the overgrowing prevalence of atrial fibrillation and obesity worldwide, more studies are encouraged to better understand the ideal lifestyle management in patients. Larger prospective cohort studies should be conducted in order to validate the results. There is also an ongoing randomized clinical trial BAROS (Bariatric Atrial Return of Sinus Trial) [NCT 04050969] which will provide more data on this topic.

Ventricular tachycardia (VT) normally occurs from an abnormal structural substrate. We report a case in which VT was caused by a large tumor in the interventricular septum. Surgical intervention was not an option due to the location of the tumor and its proximity to the coronary arteries. The patient underwent ablation and upgrade to CRT before ultimately receiving a heart transplant.

Automatic identification of VT substrate in the era of ultra-high-density mapping: Do Humans or Machines emerge victorious?Richard G. Bennett, BSc, MBChB,a Timothy G. Campbell, BSc,a Saurabh Kumar, BSc(Med)/MBBS, PhDaaDepartment of Cardiology, Westmead Hospital, Westmead Applied Research Centre, University of Sydney, Australia.Correspondence: Associate Professor Saurabh Kumar, Department of Cardiology, Westmead Hospital, Westmead Applied Research Centre, University of Sydney, Darcy Road, Westmead, New South Wales, Australia, 2145. Phone +612 8890 8140; Fax: +612 8890 8323; email: [email protected]: Timothy Campbell has received speakers’ honoraria for Biosense Webster, Inc. in the last 12 monthsFunding: Dr Saurabh Kumar is supported by the NSW Early-mid Career FellowshipKeywords: Ventricular tachycardia, local abnormal ventricular activities, electroanatomic mapping, catheter ablation, structural heart disease

Introduction: Human atria comprise distinct epicardial layers, which can bypass endocardial layers and lead to downstream centrifugal propagation at the “epi-endo” connection. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of “pseudo-focal” atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs. Methods and Results: We retrospectively analyzed ATs showing centrifugal propagation with post-pacing intervals (PPIs) after entrainment pacing suggestive of a macroreentry. A total of 26 patients had pseudo-focal ATs consisting of 15 perimitral, 7 roof-dependent, and 5 cavotricuspid isthmus (CTI)-dependent flutters. A low-voltage area was consistently found at the collision site and co-localized with epicardial layers like the: (1) coronary sinus-great cardiac vein bundle (22%); (2) vein of Marshall bundle (15%); (3) Bachmann bundle (22%); (4) septopulmonary bundle (15%); (5) fossa ovalis (7%); and (6) low right atrium (19%). The mean missing tachycardia cycle length (TCL) was 67 ± 29 ms (22%) on the endocardial activation map. PPI was 9 [0-15] ms and 10 [0-20] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 25 pseudo-focal ATs (93%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [24/26 (92%) vs. 1/6 (17%); p < 0.001]. Conclusion: Perimitral, roof-dependent, and CTI-dependent flutters with centrifugal propagation are favored by a low-voltage area located at well-identified epicardial bundles. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo-focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.

A document by Mark Davies. Click on the document to view its contents.

Background Transesophageal echocardiography (TEE) is variably performed before atrial fibrillation (AF) ablation to evaluate left atrial appendage (LAA) thrombus. We describe our experience with transitioning to the pre-ablation cardiac computed tomography (CT) approach for the assessment of LAA thrombus during the COVID-19 pandemic. Methods We studied consecutive patients undergoing AF ablation at our center. The study cohort was divided into pre- vs. post-COVID groups. The pre-COVID cohort included ablations performed during 1 year before the COVID-19 pandemic; pre-ablation TEE was used routinely to evaluate LAA thrombus in high-risk patients. Post-COVID cohort included ablations performed during the 1 year after the COVID-19 pandemic; pre-ablation CT was performed in all patients, with TEE performed only in patients with LAA thrombus by CT imaging. The demographics, clinical history, imaging, and ablation characteristics, and peri-procedural cerebrovascular events (CVE) were recorded. Results A total of 637 patients (pre-COVID n=424, post-COVID n=213) were studied. The mean age was 65.6  10.1 years in the total cohort, and the majority were men. There was a significant increase in pre-ablation CT imaging from pre to post-COVID cohort (74.8 vs. 93.9%, p=<0.01), with a significant reduction in TEEs (34.6 vs. 3.7%, p=<0.01). One patient in the post-COVID cohort developed CVE following negative pre-ablation CT. However, the incidence of peri-procedural CVE between both cohorts remained statistically unchanged (0 vs. 0.4%, p=0.33). Conclusion Implementation of pre ablation CT-only imaging strategy with selective use of TEE for LAA thrombus evaluation is not associated with increased CVE risk during the COVID- 19 pandemic.

Background: The endoscopic ablation system (EAS) is an established ablation device for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). The novel X3 EAS is now equipped with a contiguous circumferential ablation mode (RAPID mode). Aim: To determine the feasibility of single-sweep ablation using X3. Methods: Consecutive patients who underwent AF ablation using X3 were enrolled. We assessed the acute procedural data focusing on “Single-sweep PVI” defined as PVI with a single energy application using RAPID mode to complete the circular lesion set, and on “first-pass isolation” defined as successful visually guided PVI after initial circular lesion set. Results: One-hundred AF patients (56% male, age 68±10 years, 66% paroxysmal AF) were analyzed. A total of 379 of 383 PVs (99%) were isolated with X3. Single-sweep isolation and first-pass-isolation were achieved in 214 PVs (56%) and in 362 PVs (95%), respectively. Single-sweep isolation rates varied across PVs with higher rates at the superior PVs (61.2% vs. inferior PVs:49.5%, P=0.0239) and at PVs with maximal ostial diameter <24mm (57.6% vs. >24mm: 36.8%, P=0.0151). The mean total procedure and fluoroscopy times were 43.0±10 and 4.0±2 mins, respectively. In none of the patients an acute thromboembolic event (stroke or transient ischemic attack) or a pericardial effusion/tamponade occurred. A single transient phrenic nerve palsy was observed. Conclusion: The new X3 EAS allows for single-sweep PVI in 56% of PVs. The new RAPID ablation mode leads to an improved rate of first-pass isolation associated with very short procedure times without compromising safety.

Introduction: Conduction system pacing (CSP) has emerged as an ideal physiologic pacing strategy for patients with permanent pacing indications. We sought to evaluate the safety and feasibility of CSP in a consecutive series of unselected patients with congenital heart disease (CHD). Methods: Consecutive patients with CHD in which CSP was attempted were included. Safety and feasibility, implant tools and electrical parameters at implant and at follow-up were evaluated. Results: A total of 20 patients were included (10 with a previous device). Ten patients had complex forms of CHD, 9 moderate defects and 1 a simple defect. His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) were achieved in all patients (10 HBP, 5 LBBP and 5 left ventricular septal pacing). Procedure times and fluoroscopy times were prolongued (126±82 min and 27±30 min, respectively). CSP lead implant times widely varied ranging from 4 to 115 minutes, (mean 31±28 min) and the use of multiple delivery sheaths was frequent (50%). The QRS width was reduced from 144±32 ms at baseline to 116±16 ms with CSP. Implant electrical parameters included: CSP pacing threshold 0.85±0.61V; R wave amplitude 9.8±9.2mV and pacing impedance 735±253 Ohms, and remained stable at a median follow-up of 478 days (IQR 225-567). Systemic ventricle systolic function and NYHA class (1.50±0.51 vs 1.10±0.31; p=0.008) significantly improved at follow-up. Lead revision was required in one patient at day-4. Conclusions: Permanent CSP is safe and feasible in patients with CHD although implant technique is complex.