SPECIAL SESSION B-IN01:EP Concepts Ignited: Innovative Techniques andTechnologies (1)

Thursday, July 29, 2021

9:30 am - 12:00 pm

B-IN01-01

AUTOMATED LOCALISATION OF FOCALVT ORIGINSUSING IMPLANTED DEVICE EGMS AND CONVOLUTIONALNEURAL NETWORKS

Sofia Monaci MSci, Karli Gillette, Esther Puyol-Antón PhD,Ronak Rajani BM, MD, FRCP, FESC, FSCCT, Gernot Plank PhD,Andrew King PhD and Martin J. Bishop PhD

Background: The success of radiofrequency ablation for thetreatment of focal VT is dependent upon the localisation of itssources, which is highly invasive and time consuming.Objective: To automate focal VT localisation by utilizinginformation from implanted devices EGMs.Methods:A highly detailed 3D torsomodel was used to generatew3000 simulated focal VTs across the LV, and compute standard12-lead ECGs and 16 EGM vectors (from implanted devices) viathe lead field method. These time-series traceswere used to trainconvolutional neural networks (CNNs) to localize the focalsources. A separate dataset of 1000 simulated focal VTs, unseenduring training, was used for testing. Localisation accuracy(using both ECGs and EGMs) of a previously developed CNNarchitecture (Cartesian-based) was compared with our novelCNN algorithm utilizing the universal ventricular coordinate(UVCs) framework, under different parameter scenarios.Results: Implanted device EGMs successfully localized VTsources with localisation errors (8.74 mm) comparable to ECG-based localisation (6.69 mm). Our novel UVC CNN architectureoutperformed the existing Cartesian-based algorithm with errors

4.06 mm (ECGs) and 8.07 mm (EGMs). Overall localisation wasrelatively insensitive to signal noise and changes in bodycompositions (conductivities) within physiological ranges;however, displacements in ECG leads . 5 cm away from theheart, and different implanted device configurations causedprecision to decrease (errors 16-25 mm).Conclusion: EGM recordings from implanted devices may beused to successfully, and robustly, localize focal VT sources, andaid ablation planning.

B-IN01-02

DEEP SEPTAL PACING WITH RAPID LEFT VENTRICULARACTIVATION: A SIMPLIFIED APPROACH WITHOUTCONDUCTION SYSTEM TARGETING

Amrish Deshmukh MD, CCDS, Mary A. Romanyshyn MSN,CRNP, Timothy Bechtol RN, Amlish Gondal MD andPramod M. Deshmukh MD, FHRS

Background: LV septal pacing results in comparablehemodynamics to left bundle, His bundle, or biventricular pacing.Objective: We report the outcomes of a simplified method ofseptal pacing without conduction system targeting that results inrapid LV activation.Methods: In 60patients referred for pacing from11/2019-11/2020,septal pacing was performed with a 3830 lead delivered via areshaped C315 sheath (Medtronic, MN) to any site which allowedstability and a perpendicular orientation of the sheath tip to the rightseptum. The leadwasadvancedor repositioneduntil a pacedQRS,140 ms was achieved. Implant success, complications, andelectrophysiological parameters were assessed.Results: Septal lead implantation was successful in 51/60(85%). Mean age was 72616 years, 18 were women, baselineQRS was 137641 ms with 28% LBBB, 12% RBBB, and 15% RVpaced. Pacing indications were atrioventricular block (47%), RVpacing induced cardiomyopathy (21%), refractory atrial fibrillation(18%) and cardiac resynchronization (14%). Procedural durationwas 476 28 minutes and fluoroscopy time was 156 14 minuteswith a mean of 2 6 1.6 pacing sites trialed. Paced QRS was117 6 15 ms and thresholds were 0.660.5 mV at 0.560.2 ms.Left ventricular activation time measured by stimulus to peak inV5 or V6 was 82616 ms. In patients with prior wide QRS, pacedQRS was 119 6 16 ms compared to baseline 167 6 22 ms(p,0.0001). Implant success was not dependent on basal siteand LBB potentials were rare (5%). There were no complications.In follow up, thresholds remained stable.

S464 Heart Rhythm, Vol. 18, No. 8, August Supplement 2021

Conclusion: Deep septal pacing without conduction systemtargeting is safe, feasible, and results in rapid left ventricularactivation.

B-IN01-03

FOCUSED ELECTRIC FIELD ABLATION: A NOVELABLATION TECHNOLOGY INCREASES ABLATION LESIONDEPTH WITH IMPROVED SAFETY

Yonathan F. Melman MD, PhD, Paul Melman PhD,Henry D. Huang MD, FHRS, Meir Brosh BS andTimothy Larsen MD

Background: RF ablation has limited ability to deliver deeplesions, as most of the energy is dissipated in the first few mm oftissue from thecatheterand lesionexpansionoccursbyconductionof heat. Focused Electric Field (FEF) is a novel technology using aconcave-tipped catheter to create an electric field that falls offslowly with distance, increasing the amount of tissue ablated byresistive heating. FEF technology has the potential to createdeeper lesions while avoiding the risk of steam pops.Objective: To introduce FEF technology and demonstrate itsfeasibility as an ablation tool.Methods: Using an FEF catheter we performed ablation in exvivo porcine left ventricles, using real-time infrared imaging aswell as tissue histology to monitor lesion formation and compareFEF to Thermocool catheters.Results: We tested our FEF catheter by ablating in ex vivoporcine hearts. The FEF catheter was able to create deeperlesions (15.261.1mm deep at 20W compared to 6.161.0mm forThermocool at 40W). Steam pops were less frequent with FEFtechnology (6.7% vs. 37.5%). Real-time thermal imaging showsthat in contrast to an irrigated tip RF catheter which generateshigh temperatures near the catheter tip, FEF generates a moreuniform temperature profile down to depths of over 15mm withfew areas of high temperatures.Conclusion: FEF ablation creates lesions with a more uniformtemperature profile and avoids overheating of tissue thusallowing much deeper lesion formation with a lower risk of steampops. Compared to RF technology, FEFablation has the potentialto allow significantly deeper ablation than current technology withan improved safety margin.

B-IN01-04

SPATIO-TEMPORAL CAMP SIGNALING ANDARRHYTHMIAIN THE INTACT HEART

Jessica Caldwell PhD, Eric I-Ju Lee, Lianguo Wang MD andCrystal M. Ripplinger PhD, FHRS

Background: Cyclic AMP (cAMP) is a key second messengerresponsible for transducing extracellular autonomic signals intodownstream cellular responses. Yet, it is not well known how

cardiomyocyte cAMP signalling, and the resulting functionalresponses, contribute to initiation of arrhythmias in the wholeheart.Objective: To determine if cAMP imaging can be used as anindicator of cellular responses in the intact heart to betterunderstand arrhythmia mechanisms.Methods: CAMPER reporter mice that report cAMP binding bychanges in fluorescent resonance energy transfer (FRET), werecrossed with aMHC-Cre mice for cardiac-specific expression ofan Epac-based cAMP FRET sensor. At 16 weeks, hearts wereexcised and Langendorff-perfused for dual cAMP and Vm

imaging on an integrated whole heart optical imaging system.Results: Across the normal heart, cAMPwas uniformly activatedin response to b-AR stimulation with norepinephrine (NE, 1.5mM). Conversely, cAMP deactivation was slower in the base ofthe heart compared with the apex (n57, p,0.05). Perfusion withforskolin + IBMX (25 mM + 100 mM), to maximally activate cAMPand inhibit phosphodiesterases (PDE), led to a greater change incAMP activity in apical regions vs. the base (n54, p,0.001).Sequential perfusion of forskolin followed by IBMX showed thatapex-base differences only appeared following PDE inhibitionwith IBMX (n57, 5.3 % vs. 9.4 % in DFRET). These data implythat PDE activity is elevated in the apex of the heart compared tothe base. Concurrent FRETand Vm imaging during bolus NE (1.5mM) revealed that the magnitude of basal vs. apical changes inAPD80 corresponded to basal vs. apical changes in cAMPactivity. APD80 returned to baseline at 60s in the apex, comparedto the base where APD80 did not reach baseline, during 140s theimaging protocol (n52). This is similar to the decay kinetics ofcAMP in these regions.Conclusion: Using a novel whole heart optical imagingapproach, we have shown that in the normal mouse heart, thereis spatial heterogeneity of cAMP deactivation, likely due to non-uniform PDE activity. This finding may have importantimplications for electrophysiological responses andarrhythmogenesis during sympathetic activity, particularly inheart failure, where PDE activity is altered.

B-IN01-05

FUNCTIONAL EFFECTS OF GAMMA RADIATION ONHUMAN CARDIOMYOCYTES

Shi Shen, Steven A. Niederer PhD, Steven E. Williams MBChB,PhD, John Whitaker BCH, BM, Paul Bongiorni andStuart Campbell

Background: Stereotactic ablative radiotherapy (SABR) hasrecently been used for treatment of ventricular tachycardia (VT),commonly with 25Gy delivered over a single treatment. However,the anti-arrhythmic effects of SABR on cardiac tissues remainpoorly characterized and the functional effects of radiation oncardiac myocytes are unclear.Objective: We developed an in vitro method to evaluate thebiomechanical effects of radiation on engineered human hearttissues (EHTs).Methods: Thin, decellularized porcine left ventricle strips wereseeded with human induced pluripotent stem cell-derivedcardiomyocytes and human adult cardiac fibroblasts. Theresulting EHTs were cultured for 1 week and exposed to a singledose of 0 Gy (control), 12.5 Gy, or 25 Gy gamma radiation. EHTswere cultured for an additional 2 weeks before passive and activecontractile behavior was assessed. Spontaneous beat frequencywas measured two hours after exposure and then daily for twoweeks.Results: Two weeks after exposure no significant differenceswere observed between control and radiation-treated EHTs.Peak systolic force at 1Hz, time to peak force, time from peakforce to 50% relaxation, passive tissue stiffness, maximum

Special Session S465

Frank-Starling gain, and post-rest potentiation were all similar(Figure, A-F). Spontaneous beating rates were significantlyelevated hours following radiation in a dose-dependent manner,but recovered by two days (Figure, G-H).Conclusion: Short-term mechanical measurement suggestslimited effects of radiation on human EHTs. Additionalelectrophysiological studies are planned, and may clarify themechanisms through which SABR exerts anti-arrhythmic effects.

B-IN01-06

PERSONALIZED APPROACH FOR CARDIACRESYNCHRONIZATION THERAPY (CRT) IMPLANTATIONGUIDED BY REAL-TIME NON-INVASIVE 3DELECTROCARDIOGRAPHIC MAPPING

Chi Kin Au MBChB, Yat Sun Joseph Chan MBBS andBryan P. Yan MD

Background: The optimal approach for CRT implantation is notestablished.Objective: To evaluate the feasibility of CRT implantation underelectrocardiographic mapping guidance.Methods: Thirty consecutive patientswith left ventricular ejectionfraction (LVEF)�35% and conduction delay (9 LBBB and 21 non-LBBB) were recruited. A 252-electrode vest (CardioInsight,Medtronic) was worn by the patient during the procedure tomeasure the total activation time (TAT) when different pacingcombinations of biventricular pacing (BVP), His-bundle pacing(HBP) and/or left bundle branch pacing (LBBP) were tested. Thecombination that resulted in the shortest TATwould be chosen.Clinical response was defined by �1 NYHA class improvementand echocardiographic response by LV end-systolic volumereduction �15% and/or LVEF improvement �10% at 6-monthsfollow-up.Results: Final pacing configurations involved LBBP in 40%, HBPin 33%, BVP in 13% and RV or LV pacing alone in 13% ofpatients. Mean QRS duration shortened from 164618ms to128618ms and LVEF improved from 2666% to 39614% (both p,0.01). Clinical and echocardiographic response rates were80% and 73%, respectively. Super echocardiographic responderrate (final LVEF .45%) was 33%. Mean TAT (57ms vs. 87ms)was significantly lower and TAT reduction (42% vs. 12%) wassignificantly greater with final pacing-configuration compared toBVP, respectively (both p,0.01).Conclusion: Personalized approach for CRT implantation usingreal-time non-invasive electrocardiographic mapping wasfeasible and associated with better resynchronization resultscompared to BVP.

B-IN01-07

AN ARTIFICIAL INTELLIGENCE-BASED MODEL FORPREDICTION OFATRIAL FIBRILLATION FROM SINGLE-LEAD SINUS RHYTHM ECGS ENABLING SCREENING

Fredrik Viberg, Tove Hygrell MD, PhD, Erik Dahlberg MSc,Peter Charlton MEng, PhD, Katrin Kemp Gudmundsdottir MD,PhD, Jonathan Mant MD, PhD, Josef Lindman H€ornlund MSc andEmma Svennberg MD, PhD

Background: Screening for atrial fibrillation (AF) is currentlyrecommended in the ESC guidelines. To identify individuals thatmight benefit most from screening, age cut-offs or addition of co-morbidity/biomarkers are often used. A machine-learning modelcould aid in identifying patterns in normal sinus rhythmECGs thatindicate high risk for having intermittent AF.Objective: The aim of this research project was to study if anartificial intelligence-based model could predict who wouldbenefit from prolonged screening for AF using intermittent ECGsbased on a single sinus rhythm one-lead ECG.Methods: A convolutional neural network model was trained andevaluated using data from three AF screening studies:STROKESTOP I, STROKESTOP II and SAFER. In all threestudies, one-lead intermittent ECG was used for at least twoweeks in order to detect AF. A total of 443,875 ECGs from 13,080patients aged �65 years were included in the analysis. Thetraining set consisted of 247,463 ECGs from 80% of participantsin SAFER and STROKESTOP II. ECGs from the remaining 20%of participants in STROKESTOP II and SAFER and all ECGsfrom STROKESTOP I were included in the validation set for themodel. The area under the ROC curve (AUC) was measured.Sensitivity was set to 75% and specificity was calculated.Results: From a single time-point ECG the artificial intelligence-based algorithm predicted intermittent AF with an AUC of 0.68(95% CI 0.67-0.70) and specificity of 48% (CI 48-49) in the wholevalidation set. In STROKESTOP I the algorithm predicted AFwithan AUC of 0.64 (CI 0.62-0.66) and specificity of 43% (CI 40-46),and similarly in STROKESTOP II with an AUC of 0.63 (CI 0.60-0.66) and specificity of 40% (CI 35-46). Better results were seenin the SAFER study where the age distribution was wider, AUC0.83 (CI 0.81-0.86) and specificity 76% (CI 67-82).Conclusion: An artificial intelligence-enabled network has theability to predict future AF from a sinus rhythm single-lead ECG inan age homogenous group. In a screening program the algorithmmay be used as an interim step to identify individuals that mightbenefit from screening. This would reduce the number ofindividuals requiring prolonged screening and increasefeasibility.

S466 Heart Rhythm, Vol. 18, No. 8, August Supplement 2021

B-IN01-08

LOCAL ABNORMALVENTRICULAR ACTIVITY REVEALSCONDUCTION PROPERTY DIFFERENT TO SYSTOLICACTIVATION DIRECTION USING OMNIPOLARMETHODOLOGY: LAVA FLOW

Karl Magtibay BENG, MASC, Stephane Masse MASC, PE,Ahmed Niri, D. Curtis Deno MD, PhD andKumaraswamy Nanthakumar MD

Background: Sites of local abnormal ventricular activity(LAVA) potentials are thought to be attractive targets forventricular tachycardia (VT) ablation. Though they are thoughtisolated to conduction tracts, due to their discrete nature atLAVA sites, activation in these isolated tracts is not commonlydetermined. Omnipolar methodology (OT) takes advantage ofthe electric field of a wave on the myocardial surface allowingfor determination of activation direction, independent ofadjacent time annotation.Objective:Detection of Conduction Direction at LAVA sites usingomnipolar methodology.Methods: Diseased isolated human hearts (IHH) weremapped using a high-density array of 112 electrodes arrangedin a 14 by 8 grid during pacing. LAVA EGMs with distinctprimary and secondary activations were expertly identifiedfrom each IHH. If there are two discernable activationsseparated by approximately 25 ms, a marker is placedbetween activations. Activation directions for primary andsecondary activations were calculated using OT. Any OTvector that changes its angle by more than 615� wasconsidered to be significant. A total of 141 fractionated bipolarEGMs were included in the analysis.Results:Among the OT cliques that were identified at LAVA sitesfor all 4 IHHs, we observed that an average of 87%6 10% of theOT vectors changed their angle by more than 15� whencomparing the activation direction between their primary andsecondary activations.Conclusion: Discrete directional analysis at LAVA sitesseparate to systolic activation wave is possible usingOmnipolar methodology and allows for conduction direction inLAVA tracts.

B-IN01-09

MULTIPLEX GENOME EDITING FOR THE TREATMENT OFCATECHOLAMINERGIC POLYMORPHIC VENTRICULARTACHYCARDIA

Oliver Moore, Jayso'n Davidson BS, Juwan Copeland,Hannah Campbell, Tarah Word, William Lagor andXander H.T. Wehrens MD, PhD, FHRS

Background: Catecholaminergic polymorphic ventriculartachycardia (CPVT) is an inherited cardiac arrhythmia disorder thatcan cause sudden cardiac death. Variants in the ryanodine receptortype 2 gene (RYR2) cause.60% of CPVT cases. These variantsincrease RyR2 calcium (Ca2+) leak from the sarcoplasmic reticulumthat can trigger ventricular arrythmias. Current therapeutic optionsare partially effective. Previously, our lab showed that using theCRISPR/Cas9 genome editing system targeting a silent restrictionsite could disrupt a disease-causing allele preventing VT in a CPVTmouse model with RyR2-R176Q (RQ).Objective: To develop a single CRISPR/Cas9 vector that can beused to correct one of several CPVT variants.Methods:We designed single guide RNAs (sgRNA) to target theN-terminal RQ and central domain RyR2-R2474S (RS) mutationsites. We cloned vectors with sgRNA targeting RS or RQ, dualguides targeting RS + RQ, and no gRNA as control. We used anin-vitro luciferase assay to determine on and off target editingefficiencies. We generated AAV9 with CRISPR/Cas9 andinjected SC p5 mice. 6 weeks after injection, mice underwentECG stress testing with isoproterenol, caffeine, and programmedelectrical stimulation. Isolated ventricular cardiomyocytes loadedwith Fluo4 dye were analyzed with confocal line scanning.Results:We found by targeting theRQsitewith sgRNA/Cas9, 0/8mice had pacing-induced VT compared to 6/8 control (p50.03).Edited cardiomyocytes showed a significant reduction in Ca2+

spark frequency (p,0.01). When targeting the RS site withsgRNA/Cas9, 0/7 mice had inducible VT compared to 6/7 control(p50.04). The luciferase assay showed similar editing efficiencieswith sgRNAanddual gRNA (D,10%)with preservedspecificity tomutant alleles (.80%). In ongoing experiments, we expect similarefficacies in CPVT mice treated with dual gRNA/Cas9.Conclusion: CRISPR/Cas9 gene editing can treat CPVT byspecifically targeting causative mutation sites in multiple channeldomains, reducing mutant allele expression and preventing Ca2+

leak. Through successful targeting of the mutation sites, we havepromising preclinical data for gene editing as a permanent cure forCPVT.

Special Session S467

SPECIAL SESSION B-IN02:EP Concepts Ignited: Innovative Techniques andTechnologies (2)

Thursday, July 29, 2021

2:00 pm - 4:30 pm

B-IN02-01

A NOVEL EXTRAVASCULAR TEMPORARY PACING LEADSYSTEM: INITIAL RESULTS FROM A 3RD GENERATIONINVESTIGATIONAL LEAD

Martin C. Burke DO, Adrian Ebner MD, Michael Husby MPH, MS,DonE. Scheck BSEE, Angel Cardeno, Alan Marcovecchio BSEE,MSEE and Rick Sanghera BSEE, MBA

Background: The feasibility of extravascular (EV)temporary cardiac pacing has been demonstrated through aleft parasternal skin incision. This novel approach mayprovide clinical advantages over existing device alternativesthat require intravascular, endocardial or epicardialattachment. A custom EV lead, delivery tool and lead anchorsystem under development after refinements to improvedelivery, electrical performance and lead stability isdescribed.Objective: The purpose of this analysis was to evaluate short-term ambulatory electrical performance of a 3rd generation,investigational EV temporary pacing lead.Methods: Ambulatory patients (n56) who underwent atransvenous (TV) permanent pacemaker implant orreplacement were simultaneously implanted with an EVtemporary pacing lead. A custom delivery tool loaded with thelead was used to enter the anterior mediastinum. The lead wasthen secured with a suture collar at the left sternal border.Electrical performance was evaluated through analysis ofcapture thresholds, impedance, and R-wave amplitudes atinsertion and daily, up to 3 days post insertion (n53) or 7 dayspost insertion (n53).Results: Lead insertions were successful with acute capture inall 6 patients treated (83% female, 71 6 5 years, BMI 24.5 63.5 kg/m2). Mean acute measurements, including pacingcapture threshold @ 1.5 ms, impedance and R-waveamplitude were 3.9 V, 832 U, 4.7 mV, respectively. Of the 6patients, four maintained stable lead positions throughout theduration of ambulatory post-op follow up, with thresholdsconsistently below 5.0 volts. Two patients experienced leadinstability, with one lead rotating on the side and anotherpulling back. Both positionally unstable leads showed loss ofcapture at 10 Volts; however, capture @ 5.0 volts from thepulled-back lead was reattained with mild advancement, justprior to explant.Conclusion: A completely extravascular pacing leadprovides effective temporary bradycardia pacing up to 7 dayspost-op, when positional stability is achieved. Furtherdevelopment is underway to improve the Lead Anchor designfor the EV temporary pacing lead in order to gain greaterpositional stability in ambulatory patients with pacemakerindications.

B-IN02-02

DIELECTRIC-BASED TISSUE THICKNESS MEASUREDWITH A RADIOFREQUENCYABLATION CATHETER:INITIAL CLINICAL RESULTS

Larry A. Chinitz MD, FHRS, Chirag Barbhaiya,Davide Fabbricatore, Anneleen Viville, Alex Groenendijk,Tom Haagen, Yitzhak Schwartz MD, Eitan Oren, Matthew Sulkin,Dimitri Buytaert MEng and Tom De Potter MD, PhD

Background: Current algorithms that indicate adequacy ofradiofrequency (RF) lesion formation incorporate parameterssuch as contact force, power, and duration, but omit tissuethickness. A new dielectric-based method for measuring tissuethickness (DTT, Wall Viewer�) at the catheter-tissue interfacehas recently been developed (pre-market). DTT performance inclinically relevant atrial anatomy, such as the cavotricuspidisthmus (CTI), is unknown.Objective: To evaluate the correlation between DTTand tissuethickness measured with intracardiac echocardiography (ICE) insubjects undergoing CTI ablation.Methods: Eight subjects at two centers underwent a CTIablation (NCT03858361 and NCT04438395). Right atrialmaps were created with an electroanatomic mapping system(KODEX-EPD). The DTT algorithm is based on a pre-trainedalgorithm model that incorporates real-time catheter positionand local dielectric tissue interrogation by catheterelectrodes. Prior to ablation, DTT measurements were takenwith an ablation catheter (ThermoCool� SF) along the CTIby blinded operators and compared with tissue thicknessdetermined on stored CTI ICE images after the procedure.Bi-directional CTI block was confirmed with differentialpacing.Results: Average RA mapping time was 23 6 5 min. Acute bi-directional block was confirmed in all subjects. CTI thicknessmeasured with ICE (range 1.3 - 5.0 mm) was compared to DTTtissue thickness at 43 points. There was a significant linearcorrelation between DTTand ICE tissue thicknesses (p, 0.001,slope: 0.73 and r: 0.57). In total, 86.0% (37/43) of DTT values fellwithin 1.5 mm of ICE measurements with the largest deviation of2.1 mm.Conclusion: Clinically relevant atrial tissue thickness wasaccurately measured by a dielectric-based method with acommercially available RF ablation catheter. Real-time tissuethickness measurement may better inform RF dosing toensure lesion transmurality while limiting collateral structuredamage.

B-IN02-03

USING PULSED ELECTRIC FIELDS TO CAUSE FOCALFIBROSIS IN THE INTERVENTRICULAR SEPTUM

Thomas P. Ladas BSE, MD, MSE, PhD, Martin van Zyl MBChB,Nicholas Yick Loong Tan MD, MS, Georgios Christopoulos,Jason A. Tri, Omar Ziad Yasin MD, MS, Adetola Ladejobi MBBS,MPH, Mariam Khabsa, Richard J. Connolly PhD,Christopher V. DeSimone MD, PhD, Ammar M. Killu MBBS,FHRS, Elad Maor MD, PhD and Samuel J. AsirvathamMD, FHRS

S468 Heart Rhythm, Vol. 18, No. 8, August Supplement 2021

Background: Pulse electric fields (PEF) are being investigatedas an alternative ablation modality to traditional radiofrequencyablation for modification of myocardial substrate.Objective: Assess the extent and time course of myocardial scarformation caused by application of PEF at the interventricularseptum.Methods: Four-week survival experiments were performed in 8canines. Energy was delivered using ablation catheters in bipolarconfiguration to apply PEF to the septum. Two animals wereadministered pulses at microsecond pulse widths and sixreceived nanosecond pulses for a total 75-189 J delivered peranimal. MRI studies were performed in 4 of the 8 animals. Scarformation was assessed by measuring late gadoliniumenhancement (LGE) and confirmed by histology.Results: Sites of PEF delivery exhibited myocardial edema ontriple inversion recovery and early scar with some LGE visibleafter 7 days. Lesion volumes were larger for transmuralconfigurations vs. bipolar PEF delivered in a single cardiacchamber (10.76 2.3 cm3 vs. 2.96 1.1 cm3). At 30 days, lesionspredominantly exhibited LGE and total lesion volumes weresimilar for both groups (5.3 6 2.4 cm3 vs. 4.0 6 0.2 cm3).Transmural MRI lesions were achieved when bipolar electrodeswere placed on either side of the septum, and total lesion volumewas dose-dependent. Myocardial fibrosis was identified onhistology. Bipolar configurations entirely within a chamberproduced superficial lesions, even with delivery of higher energy.Conclusion: Application of PEF to the myocardium can causesubstrate modification, including transmural fibrosis. Lesionvolume is dose-dependent for transmural electrodeconfigurations.

B-IN02-04

TRANSHEPATIC ACCESS TO FACILITATE LEADEXTRACTION IN A PATIENT WITH INTERRUPTEDINFERIOR VENA CAVA

James Arthur Mann MD, Syed Rafay Ali Sabzwari MBBS, MD,Shu Cheong Chang MD, Johannes C. von Alvensleben MD,CEPS-P, Martin Runciman MD, Max Mitchell MD,Ozlem Turan MD, Wendy S. Tzou MD, FHRS,Kathryn K. Collins MD, FHRS, CEPS-P andMatthewM. ZipseMD

Background: Unconventional approaches to achievetransvenous pacing may be required in patients with congenitalvascular anomalies and vascular occlusion.Objective: We report a case of a patient with congenitalinterruption of the IVC and multiple venous occlusions requiringtranshepatic access for dual chamber pacing system extractionand re-implantation.Methods: N/AResults: A 21 year old female with congenital heart disease anda right axillary transvenous pacemaker implanted at age 11 forcomplete heart block presented with lead fracture. Her historywas notable for coarctation repair, bicuspid aortic valve andclosure of a large VSD. Vascular access to the heart was limitedby a right subclavian vein occlusion extending to the SVCassociated with indwelling leads, congenital interruption of theIVC, bilateral IJ occlusions, contralateral L subclavian occlusionand R iliac vein occlusion. A plan was made for lead extractionand placement of new leads. Temporary pacing was achievedwith a deflectable decapolar catheter via the left femoral vein tothe azygous vein to the SVC. During extraction leaddislodgement occurred before the mechanical extraction sheathcould be advanced across the subclavian occlusion.Transhepatic accesswas obtained to snare the lead tip and applytraction for sheath advancement. With vascular access to theheart achieved, new RA and RV leads were positioned. Thetranshepatic venotomy was closed with a vascular plug. Thepatient was discharged without complication.Conclusion: Transhepatic venous access is a safe and effectivealternative to more conventional approaches to lead extractionwhen limited by congenital vascular malformations or occlusion.

Special Session S469

B-IN02-05

CATHETER-BASED CARDIOPULMONARY NERVESTIMULATION IMPACTS LEFT VENTRICULARCONTRACTILITYAND RELAXATION: FIRST IN HUMANEXPERIENCE

Steven Richard Mickelsen MD, CEPS, Christian Marin MD,Adrian Ebner MD and Michael Cuchiara

Background: There are limited strategies addressing thereversible hypoperfusion and fluid retention observed in acutedecompensated heart failure (ADHF). Aberrant autonomic reflexphysiology is believed to contribute to clinical decompensation.Our previous work demonstrated catheter-basedcardiopulmonary nerve stimulation (CPNS) can increase cardiaccontractility.Objective: To evaluate short-term safety and feasibility of a novelCPNS System (Cardionomic, Inc. New Brighton, MN).Methods: Subjects (n57) undergoing a catheterizationprocedure or ICD/CRT implant were studied. After indexprocedure, the investigational CPNS neuromodulation catheterwas delivered to the right PA. Stimulus sequences were usedto evoke cardiac responses. Changes in LV contractility(LV dP/dt max), LV relaxation (LV dP/dt min), arterial bloodpressure, and HR were measured with and without stimulationover a period of 1-3 hours.Results: No adverse events occurred over the course of thestudy. All subjects (100%) exhibited increased contractility withCPNS (average stimulation time 5 102 sec). The increase inLV contractility was substantial 58% [6, 173%]. LV relaxation11% [-11, 70%], arterial pulse pressure 20% [4, 30%] andmean arterial pressure 7% [-1, 16%] also increased while HRwas relatively unchanged 0% [-10, +8%].Conclusion: CPNS to increase cardiac contractility is feasibleand likely safe. Heart rate neutral changes in LV contractility,relaxation, and arterial blood pressure were reproducible overthe short period of testing. Additional and longer-term studiesare required to assess the impacts on clinical heart failureendpoints.

B-IN02-06

REAL-LIFE PERFORMANCE, LONG-TERM ROBUSTNESS,AND ABSENCE OF RACE BIAS IN THE ARTIFICIALINTELLIGENCE ENHANCED ELECTROCARDIOGRAM FORTHE DETECTION OF LEFT VENTRICULAR SYSTOLICDYSFUNCTION

David Harmon, Michal Shelly BSc, Anna Svatikova MD, PhD,Demilade A. Adedinsewo MBChB, Rickey E. Carter PhD,Peter A. Noseworthy MD, FHRS, Suraj Kapa MD, FHRS,Francisco Lopez-JimenezMD,MSc, Paul A. FriedmanMD, FHRSand Zachi Itzhak Attia MSEE, PhD

Background: We previously reported on the application ofartificial intelligence (AI) to a standard ECG (AI-ECG) todetect left ventricular systolic dysfunction (LVSD). This toolremains promising for a rapid, inexpensive, point of carescreening strategy for patients with previously undiagnosedLVSD. Some AI models require ongoing re-training, and haveracial bias.Objective:We assessed the AI-ECG for detecting EF�40%withrespect to race and ethnicity, time, and ECG rhythm over a fullyear after the model was developed, in the absence of retrainingto assess its robustness.Methods: ECGs acquired in 2019 at Mayo Clinic in Minnesota,Arizona, and Florida with an echocardiogram performed within14 days were analyzed (n544,986 unique patients). The areaunder the receiver operating characteristics curve (AUC) wascalculated for test performance among racial and ethnicgroups, various rhythms and conduction disturbances, andover time.Results: For the complete cohort, the model had an AUC of0.903, similar to the AUC in the derivation cohort (AUC5 0.90 forEF�40%). Accuracy was stable over time. AUCwas similar for allracial and ethnic groups with the lowest (AUC50.90) for white-non-Hispanic patients and highest (AUC50.93) for AmericanIndian/Native Alaskan patients. Patients with an ECG of “normalsinus rhythm” exhibited an AUCof 0.91 for detecting EF�40%. Allother ECG rhythms or ECG diagnoses had AUCs between 0.79and 0.91.Conclusion: The ability of the AI-ECG to detect LV dysfunction isstable over time in the absence of re-training and robust withrespect to multiple variables, including patient race and ethnicity,time of year, and variations in ECG rhythm and conductiondisturbances.

B-IN02-07

LOCALIZATION OF OUTFLOW TRACTPREMATURE VENTRICULAR BEATS ORVENTRICULAR TACHYCARDIA IN SURFACEELECTROCARDIOGRAMS USING A CONVOLUTIONALNEURAL NETWORK

S470 Heart Rhythm, Vol. 18, No. 8, August Supplement 2021

Shadi Kalantarian MD, MPH, Sean Abreau,Edward P. Gerstenfeld MD, FHRS, Geoffrey H. Tison MD, MPHand Melvin M. Scheinman MD, FHRS

Background: ECG based algorithms for localization ofoutflow tract (OT) premature ventricular complexes(PVCs) have variable sensitivity and specificity.Machine learning may identify visually imperceptibleECG changes and augment predictive accuracy, especially inearly disease stages.Objective: To compare a Convolutional Neural Network (CNN)with manual PVC localization of left vs. right ventricular (RV vs.LV) OT PVC.Methods: All patients with successful ablation ofRV-LV OT from 1/2013-1/2020 were included if they hadat least one standard 12-lead ECG recorded with aclinical PVC before ablation. PVC origin was defined bythe site of successful ablation excluding LV summit,aorto-mitral continuity and para-hisian PVCs. Successwas defined as absence of the targeted PVC for the 24 hrpost procedure monitoring. We compared CNNperformance to 3 OT PVC localization algorithms (Table1). Patient-level ECG data were split into Training,Validation and Test Datasets in a ratio of approximately7:1:2. Results are reported as averaged across 10random splits of the data and model initializations forrobustness.Results: 308 ECGs (86 RVOT, 43 LVOT, 179 sinus) from75 patients were used for CNN development. CNNclassified RVOT PVC with similar sensitivity toalgorithms but with higher specificity (Table 2). ForLVOT PVC, CNN specificity was higher, and sensitivitywas higher than all but one of the manual algorithms.The CNN area under the receiver operatingcharacteristic curve for LVOTand RVOTwere 0.929 and 0.914,respectively.Conclusion: A CNN can achieve higher specificityat similar or higher sensitivity compared tomost published algorithms to differentiate right from left OTPVCs.

B-IN02-08

PULSED FIELD ABLATION AND HEAT GENERATION:ELECTRODE-TISSUE TEMPERATURE ANALYSIS FROMTHE PULSED AF TRIAL

Atul Verma MD, FHRS, Lucas V.A. Boersma MD, PhD,David E. Haines MD, FHRS, Francis E. Marchlinski MD, FHRS,Hugh Calkins MD, FHRS, Prashanthan Sanders MBBS, PhD,FHRS, Douglas L. Packer MD, FHRS, Andrea Natale MD,FHRS, Gerhard Hindricks MD, Karl-Heinz Kuck MD, FHRS,John D. Hummel MD, FHRS, Lars M. Mattison PhD,Brian T. Howard BS, MS, PhD and Bradley R. Wilsmore BS,MB, MBBS, PhD, CCDS, CEPS-A

Background: Pulsed Field Ablation (PFA) is anemerging alternative energy source to thermal-basedablation. PULSED AF is a first-in-human study evaluating thesafety and efficacy of PFA for pulmonary vein (PV) isolation,but the thermal effects of PFA on human myocardial tissueare unknown.

Objective:Quantify the electrode temperature rise following PFAenergy application in PULSED AF patients.Methods: Patients (n520) undergoing first-time PV isolationwere treated with PFA using a circular, over-the-wirecatheter. Electrode temperature was recorded from all 9electrodes for 1 second following each PFAapplication. Thermocouples were located on the tissue sideof the gold electrodes to provide tissue-interfacetemperatures.Results: Acute PV isolation was achieved in 100% of PVswithout PFA system related serious adverse events.Different PFA levels showed the following temperature rises:1.7 6 1.6�C (1200 V), 1.9 6 2.0�C (1400 V) and 3.0 6 3.0�C(1500 V) (r250.9). Electrode temperature rise at the 1500 Vvaried slightly across all four veins with temperature risesof 3.2 6 2.8�C (LSPV) 3.6 6 3.7�C (LIPV) 2.9 6 2.7�C(RSPV) 2.8 6 3.0�C (RIPV). In patents with esophagealtemperature monitoring, no appreciable changes wereobserved (n58).Conclusion: This is the first electrodetemperature analysis associated with PFA. PFA onlycauses a limited temperature rise followingdelivery confirming the primarily non-thermal nature of lesioncreation.

B-IN02-09

A MACHINE LEARNING BASED APPROACH FOR REALTIME RHYTHM TRACKING

Pratik Shah, Nathan Angel PhD, Xinwei Shi PhD andDerrick Chou PhD

Background: Conventional activation mapping is achieved instable rhythms by annotating local activation timescompared to a reference EGM. Efficiently mappingquasi stable rhythms such as short bursts of AT during SRor AF may be of interest, but traditional mappingapproaches are unable to adapt to such transitoryevents. Real-time, auto-identification of uniquerhythms during transient conditions can facilitateadaptive mapping of multiple rhythms during a singleacquisition.

Special Session S471

Objective: Demonstrate the accuracy of a novel hybrid machinelearning (ML) approach to classify various cardiac rhythms inreal-time.Methods: Unipolar CS EGMs from 24 subjects labeledas sinus, AFL, AF, or paced rhythms were collectedand downsampled. Each CS EGM was transformed to awavelet scalogram. Scalogram images were used totrain (80%) and validate (20%) a Convolutional NeuralNetwork (Fig. 1, A). The performance was evaluatedfor classification accuracy and positive predictivevalue (PPV).Results: A total of 2559 EGM data segments (1-secduration), each comprised of 3 CS channels were analyzed.Examples of CS morphologies and their waveletrepresentation are presented in Fig. 1, B. The hybrid MLmethod achieved 99.2% classification accuracy over allrhythm types with an average processing time of 80ms foreach data segment. PPV for SR, AF, and AFL was 100% and97% for paced rhythms.Conclusion: When trained and compared to clinicallydetermined rhythms, this ML method successfullyclassified SR, AFL, AF, and paced rhythms accurately atreal-time rates. Clinically, this method may enablemapping systems to automatically adapt to rhythmchanges and track transient rhythms during continuousacquisition.

B-IN02-10

USING HOLTER MONITOR TO RECORD SKINSYMPATHETIC NERVE ACTIVITY

Xiao Liu MD, Joselyn Ricafrente RN, Mary E. Leier NP,Harrison Dinh PA, Thomas H. Everett BEng MS, PhD, FHRS andPeng-Sheng Chen MD, FHRS

Background: neuECG is a new method to simultaneouslyrecord ECG and skin sympathetic nerve activity (SKNA). Theavailable equipment for neuECG recording is expensive and notfully portable.Objective: To test the hypothesis that Bittium Faros 180, a small(4.8 x 2.9 x 1.2 cm) Holter monitor, can be used to recordneuECG in ambulatory outpatients.Methods: We placed conventional ECG patch electrodes onthe chest of 5 female outpatients (39617 years old). Theelectrodes were connected to Biomation ME6000(sampling rate 10,000 Hz) and Faros (sampling rate 1,000Hz) during orthostatic testing (from supine to 3-minstanding, then sitting). The ME6000 signals werebandpass filtered 500-1000 Hz while the Faros signals werehigh pass filtered at 300 Hz to display the SKNA. The sameoriginal signals were bandpass filtered 0.05-150 Hz todisplay ECG.Results: The total recording time was 18.8619.7 minutes/patient. As shown in Panel A, these two devices recordedsimilar patterns of nerve activities. While the amplitude of theSKNA was lower in Faros than in ME6000, they track eachother over time (Panel B) with good correlations (Panel C,each dot is 1-min). For all 5 patients studied, the averageSKNA (aSKNA) at supine, 1, 2 and 3 min after standing up andafter sitting down were 1.0260.34, 1.4360.37, 1.1860.12,1.1960.28 and 1.2060.18 mV for ME6000 and were0.9460.05,1.0560.10, 1.0160.09, 0.9960.08, 0.9860.09 mVfor Faros 180, respectively. The r values averaged 0.774(N55, P,0.001 for all).Conclusion: Holter monitors with sampling rate of1000 Hz can be used to record neuECG. It will enablethe direct measurements of SKNA in ambulatoryoutpatients to study the neural mechanisms of cardiacarrhythmias.

S472 Heart Rhythm, Vol. 18, No. 8, August Supplement 2021