Reflections from the Book of the Dead: Weighing the Impact of Epicardial Fat on Atrial Fibrillation Vulnerability T. Jared Bunch MDDepartment of Medicine, School of Medicine, University of Utah, Salt Lake City, UtahAddress for correspondence: T. Jared Bunch, M.D.University of Utah School of Medicine Department of Internal Medicine Division of Cardiovascular Medicine 30 North 1900 East, Room 4A100 Salt Lake City, UT 84132 Phone: 801-213-2387 E-mail: jared.bunch@hsc.utah.edu

We previously introduced the Inverse Solution Guidance Algorithm (ISGA) methodology using a Single Equivalent Moving Dipole model of cardiac electrical activity to localize both the exit site of a re-entrant circuit and the tip of a radiofrequency (RF) ablation catheter. The purpose of this study was to investigate the use of ISGA for ablation catheter guidance in an animal model. Ventricular tachycardia (VT) was simulated by rapid ventricular pacing at a target site in eleven Yorkshire swine. The ablation target was established using three different techniques: a pacing lead placed into the ventricular wall at the mid-myocardial level (Type-1), an intracardiac mapping catheter (Type-2), and an RF ablation catheter placed at a random position on the endocardial surface (Type-3). In each experiment, one operator placed the catheter/pacing lead at the target location, while another used the ISGA system to manipulate the RF ablation catheter starting from a random ventricular location to locate the target. The average localization error of the RF ablation catheter tip was 0.31 ± 0.08 cm. After analyzing ~35 cardiac cycles of simulated VT, the ISGA system’s accuracy in locating the target was 0.4 cm after 4 catheter movements in the Type-1 experiment, 0.48 cm after 6 movements in the Type-2 experiment, and 0.67 cm after 7 movements in the Type-3 experiment. We demonstrated the feasibility of using the ISGA method to guide an ablation catheter to the origin of a VT focus by analyzing a few beats of body surface potentials without electro-anatomic mapping.

Introduction: The sinoatrial node (SAN) should be identified before superior vena cava (SVC) isolation to avoid SAN injury. However, its location cannot be identified without restoring sinus rhythm. This study evaluated the usefulness of the anatomically defined SAN by comparing it with the electrically confirmed SAN (e-SAN) and aimed to establish a safe and more efficient anatomical reference for SVC isolation than the previously reported reference of the roof of the right superior pulmonary vein (RSPV roof). Methods and Results: The e-SAN was identified as the earliest activation site in the electro-anatomical map obtained during sinus rhythm. The anatomically defined SAN, the cranial edge of the crista terminalis (CT) visualized with intracardiac echocardiography (CT top), and the RSPV roof were tagged on one map. The distance from the e-SAN to each reference was measured. Among 81 patients, the height of the e-SAN from the CT top was −3.5 ± 10.3 mm. The e-SAN existed below 10 mm above the CT top in 78 (96%) patients and below the RSPV roof in 77 (95%) patients. A longer SVC sleeve was measured from 10 mm above the CT top compared to the RSPV roof (28.7 ± 11.2 vs. 22.5 ± 11.3 mm, p <0.001). Faster heart rate predicted an e-SAN location higher than the CT top (adjusted OR [95% CI]; per 10 bpm increase: 1.6 [1.15–2.22], p <0.01). Conclusion: The CT top is useful in predicting the upper limit of the e-SAN and can provide a useful reference for SVC isolation.

Introduction Ventricular arrhythmias (VAs) are a major cause of morbidity and mortality in patients with heart disease. Recent studies evaluated the effect of renal denervation (RDN) on the occurrence of VAs. We conducted a systematic review and meta-analysis to determine the efficacy and safety of this procedure. Methods and results A systematic search of the literature was performed to identify studies that evaluated the use of RDN for the management of VAs. Primary outcomes were reduction in the number of VAs and implantable cardioverter-defibrillator (ICD) therapies. Secondary outcomes were changes in blood pressure and renal function. Ten studies (152 patients) were included in the meta-analysis. RDN was associated with a reduction in the number of VAs, ATP (antitachycardia pacing), ICD shocks and overall ICD therapies of 3.53events/patient/month (95%CI=-5.48 to -1.57), 2.86events/patient/month (95%CI=-4.09 to -1.63), 2.04events/patient/month (95%CI=-2.12 to -1.97), and 2.68events/patient/month (95%CI=-3.58 to -1.78), respectively. Periprocedural adverse events occurred in 1.23% of patients and no significant changes were seen in blood pressure or renal function. Conclusions In patients with refractory VAs, RDN was associated with a reduction in the number of VAs and ICD therapies, and was shown to be a safe procedure. KEYWORDS: Renal denervation, ventricular arrhythmias, implantable cardioverter-defibrillator, antitachycardia pacing, ICD shocks.

Abstract poster

We congratulate Kar et al. on their elegant study evaluating ex-vivo temperature profiles and the resulting thermal injury formation on the epiesophageal surface during radiofrequency (RF) ablation. In addition to being the first study to detail temperature profiles inclusive of the epiesophageal surface during RF ablation, we believe that the results add further concern to the use of temperature sensing technology in the quest to reduce esophageal injury. Three recent clinical trials have evaluated the efficacy of luminal esophageal temperature (LET) monitoring and found either no benefits, or signals of harm. On the other hand, two pilot RCTs suggest benefits of active cooling, and a large RCT, the IMPACT study, further confirms this benefit by finding an 83% reduction in esophageal lesion formation using an active cooling device. With no degradation in ablation efficacy, as well as a reduction/elimination of the need for fluoroscopy and reports of shortened procedure time with active cooling technology, the data of Kar et al., combined with growing clinical data, suggest that continued use of LET monitoring may be unjustified.

Introduction: The subcutaneous-ICD (S-ICD) and its electrode were developed to avoid long-term complications of transvenous leads in the vasculature. Methods: We report a case of unexpected, inappropriate S-ICD shocks due to oversensing of high amplitude, non-physiologic, electrical noise artifacts that were not preceded by high impedance alerts or sensing electrogram noise detections. Results: Following explant, high-magnification, X-ray imaging of the S-ICD electrode demonstrated partial fracture of the distal sensing conductor located near a short radius bend in the electrode at the electrode-header interface. Conclusions: Clinicians should be aware of a potential for fatigue failure fracture of the S-ICD electrode. Recommendations for systematic S-ICD follow-up and troubleshooting are discussed.

High power, short duration ablation: at least for the right pulmonary vein carina, maybe not so fastGustavo S. Guandalini, MD a and Francis E. Marchlinski, MD aa Section of Cardiac Electrophysiology, Hospital of the University of Pennsylvania, Philadelphia, PACorresponding author: Dr. Francis E. Marchlinski, Division of Cardiovascular Medicine, Electrophysiology Section, Hospital of the University of Pennsylvania, 3400 Spruce Street, 9 Founders Pavilion, Philadelphia, Pennsylvania 19104. E-mail: Francis.Marchlinski@pennmedicine.upenn.edu.The authors have no conflicts to disclose.Word count: 1,170.This research was supported by the Richard T and Angela Clark Innovation Fund in Cardiovascular Medicine.

Introduction: Presence of preferential pathway conduction is mostly detected as fractionated presystolic potentials preceding the QRS onset during premature ventricular contractions (PVCs) and late potentials during sinus rhythm (SR), but the electrophysiologic mechanisms and significance of these potentials have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was 3-dimensionaly visualized by coherent mapping with the conduction velocity vector. Methods: Five PVCs (2 from the left coronary cusp, 2 from the commissure of the left and right coronary cusps, and 1 from the pulmonary artery) in 4 patients for which a fractionated presystolic potential during the PVCs and late potential during SR were recorded at the successful ablation site were reviewed, and 3-dimensional coherent activation maps with the conduction velocity vector during the PVCs and SR were reconstructed. Results: At the successful ablation site, an “M”-shaped discrete presystolic-potential and “W”-shaped discrete late-potential were recorded in all patients. The configuration of the flipped electrogram of the presystolic-potential nearly matched that of the electrogram exhibiting the late-potential. We created coherent activation maps annotating the onset of the presystolic potentials during the PVCs, and the offset of the late potentials during SR, which suggested bidirectional conduction of the preferential pathway connecting the PVC origin to the myocardium. Conclusion: In this case series, the M-shaped presystolic potential and W-shaped late potential were reversely matched. These reverse potentials, and the coherent activation vector maps during PVCs and SR suggested bidirectional conduction of the preferential pathway in opposite directions.

Introduction: We aimed to investigate whether a modified implantation method facilitating a fully open umbrella can reduce the pericardial effusion/pericardial tamponade (PE/PT) rate after left atrial appendage closure (LAAC) with the LAmbre device compared with the conventional method (CM) in patients with non-valvular atrial fibrillation (NVAF). Methods and results: Patients with NVAF who received either isolated LAAC or combined catheter ablation and LAAC using the LAmbre device at the First Affiliated Hospital of Wenzhou Medical University from January 2018 to December 2019 were enrolled. CM was used for device implantation in the initial 59 patients, while a modified method (MM) was used in the remaining 165 patients. Successful implantation was achieved in 98.3% of patients in the CM group and in 98.8% in the MM group. A higher rate of a fully open umbrella (98.8% vs 69%, P<0.001), less requirement for recapture (46% vs 62.1%, P=0.036), and a lower incidence of delayed PE/PT (1.2% vs 8.6%, P=0.005) were found in the MM group compared with in the CM group. All of the five delayed PT events occurred in patients with combined treatment. An umbrella that was not fully open was the only factor associated with delayed PE/PT events in a multivariable Cox model. Conclusions: LAAC with the LAmbre device using an MM significantly increases the rate of a fully open umbrella and decreases the requirement for recapture and the incidence of delayed PE/PT. This method is more effective in patients with combined treatment.

Why Does Catheter Ablation of Premature Ventricular Contractions

The excellent review by Houmsse and Daoud of techniques and methods utilized to protect the esophagus from injury during atrial fibrillation (AF) ablation appropriately concludes that considering the ease of use, minimal side effects, and low costs associated with esophageal protection devices, compelling evidence exists for use of esophageal protection as routine care for AF ablation. Some additional data are available which would warrant inclusion in further consideration of this topic. Three recent studies have demonstrated the inability of LET monitoring to protect the esophagus, whereas meta-analysis of three studies of manual cooling using direct liquid instillation suggests that this approach significantly reduced high-grade lesion formation (OR of 0.39, 95% CI 0.17 to 0.89). Moreover, three studies using a commercially available cooling device FDA cleared for thermal regulation have shown reductions in esophageal lesion severity without degradation in ablation efficacy.

Background: Catheter ablation is highly effective for AVNRT. Generally junctional rhythm(JR) is an accepted requirement for successful ablation however there is a lack of detailed prospective studies to determine the characteristics of JR and the impact on slow pathway conduction. Methods: Multicentre prospective observational study evaluating the impact of individual radiofrequency(RF) applications in typical AVNRT(Slow/Fast). Characteristics of JR during ablation were documented and detailed testing was performed after every RF application to determine outcome. Procedural success was defined as ≤1 AV nodal echo. Results: Sixty-seven patients were included(mean age 53±18years, 57% female and a history of SVT 2.9±4.7years). RF(50w,60degrees) ablation for AVNRT was applied in 301 locations with JR in 178(59%). Successful slow pathway modification was achieved in 66(99%) patients with slow pathway block in 30(46%). Success was associated with JR in all patients. Success was achieved in 6 patients with RF<10 seconds. There was no significant difference in the CL of JR during RF between effective(587±150ms) vs ineffective (611±193ms,p=0.4) applications. Inadvertent JA-block with immediate termination of RF was observed in 19(28%) patients with AVNRT no longer inducible in 14(74%). Freedom from SVT was achieved in 66(99%) patients at a mean follow up of 15±6 months. Conclusion: In this prospective study, JR was required during RF for acute success in AVNRT. Cycle length of JR during RF was not predictive of success. Unintended JA block during faster JR was associated with slow pathway block. RF applications as short as 10s resulting in junctional rhythm may be successful in some patients.

Rate dependent exit block across the pulmonary veins has been previously described immediately following catheter ablation. We report the case of rate dependent PV block seen at repeat ablation 7 years after the index procedure. To our knowledge, this is the first report of chronic rate dependent exit block (i.e. Rate dependent exit block discovered 7 years after circumferential PV antral isolation). We believe that, as with CTI ablation, rate independent pulmonary vein isolation should be confirmed.

Introduction:Stand-alone substrate ablation without baseline ventricular tachycardia (VT) induction and activation mapping has become a standard VT ablation strategy. We sought to evaluate the influence of baseline VT inducibility and activation mapping on ablation outcomes in patients with structural heart disease (SHD) undergoing VT ablation. Methods:This is a single center, observational and retrospective study including consecutive patients with SHD and documented VT undergoing ablation. Baseline VT induction was attempted before ablation in all patients and VT activation mapping performed when possible. Ablation was guided by activation mapping for mappable VTs plus substrate ablation for all patients. Ablation outcomes and complications were evaluated. Results: 160 patients were included (203 VT ablation procedures) and were classified in 3 groups according to baseline VT inducibility: group 1 (non inducible, n=18), group 2 (1 VT morphology induced, n=53), and group 3 (>1VT morphology induced, n=89). VT activation mapping was possible in 35%. After a median follow-up of 38.5 months, baseline inducibility of >1VT morphology was associated with a significant incidence of VT recurrence (42% for group 3 vs. 15.1% for group 2 and 5.6% for group 1, Log-rank p<0.0001) and activation mapping with a lower rate of VT recurrence (24% vs. 36.3%, Log-rank p=0.035). Independent predictors of VT recurrences and mortality were baseline inducibility of >1VT morphology (HR 12.05 IC 95% 1.60-90.79, p=0.016) and LVEF<30% (HR 2.43 IC 95% 1.45-4.07, p=0.001), respectively. Complications occurred in 11.2% (5.6% hemodynamic decompensation). Conclusions:Baseline VT inducibility and activation mapping may add significant prognostic information during VT ablation procedur

Background: Contrast computed tomography (CT) is a useful tool for the detection of intracardiac thrombi. We aimed to assess the accuracy of the late-phase prone-position contrast CT (late-pCT) for thrombus detection in patients with persistent or long-standing persistent atrial fibrillation (AF). Methods: Early and late-phase pCT were performed in 300 patients with persistent or long-standing AF. If late-pCT did not show an intracardiac contrast defect (CD), catheter ablation (CA) was performed. Immediately prior to CA, intracardiac echocardiography (ICE) from the left atrium was performed to confirm thrombus absence and the estimation of the blood velocity of the left atrial appendage (LAA). For patients with CDs on late-pCT, CA performance was delayed, and late-pCT was performed again after several months following oral anticoagulant alterations or dosage increases. Results: Of the 40 patients who exhibited CDs in the early phase of pCT, six showed persistent CDs on late-pCT. In the remaining 294 patients without CDs on late-pCT, the absence of a thrombus was confirmed by ICE during CA. In all six patients with CD-positivity on late-pCT, the CDs vanished under the same CT conditions after subsequent anticoagulation therapy, and CA was successfully performed. Furthermore, the presence of residual contrast medium in the LAA on late-pCT suggested a decreased blood velocity in the LAA (≤ 15 cm/s) (sensitivity = 0.900 and specificity = 0.621). Conclusions: Late-pCT is a valuable tool for the assessment of intracardiac thrombi and LAA dysfunction in patients with persistent or long-standing persistent AF before CA.

Using an Accelerated Junctional Rhythm to Predict the Success and Safety of Slow AV Nodal Pathway Ablation G. Neal Kay MD

Background: Data related to electrophysiologic characteristics of atypical atrial flutter (AFL) following atrial fibrillation (AF) ablation and its prognostic value on repeat ablation success are limited. Methods: We studied consecutive patients undergoing a repeat LA ablation for either recurrent AF or atypical AFL, following 3 months after index AF ablation, between January 2012 and July 2019. The demographics, procedural data, complications, and 1-year arrhythmia-free survival rates were recorded for each subject after the first repeat ablation. Results: Of the total 336 included patients, 102 underwent a repeat ablation for atypical AFL and 234 for recurrent AF. The mean age was 63.7  10.7 years, and 72.6 % of patients were male. The atypical AFL cohort had significantly higher LA diameters (4.6 vs. 4.4 cm, p=0.04) and LA volume indices (LAVi; 85.1 vs. 75.4 ml/m2, p=0.03) compared to AF patients at repeat ablation. Atypical AFLs were roof-dependent in 35.6% and peri-mitral in 23.8% of cases. Major complications at repeat ablation occurred in 0.9 % of the total cohort. Arrhythmia-free survival at one year was significantly higher in the recurrent atypical AFL than the recurrent AF cohort (75.5 vs. 65.0 %, p=0.04). Conclusion: In our series, roof-dependent flutter is the most common form of atypical atrial flutter post AF ablation. Patients developing atypical AFL after index AF ablation have greater LA dimensions than patients with recurrent AF. The success rate of first repeat ablation is significantly higher among patients with recurrent atypical AFL compared to recurrent AF after index AF ablation.