Invasive Electrophysiological Study Research Articles

Permanent pacemaker implantation in unexplained syncope patients with borderline sinus bradycardia and electrophysiology study-proven sinus node disease.

BackgroundSignificant sinus bradycardia (SB) in the context of sinus node dysfunction (SND) has been associated with neurological symptoms. The objective was to evaluate the effect of permanent pacing on the incidence of syncope in patients with rather mild degrees of SB, unexplained syncope, and “positive” invasive electrophysiologic testing.MethodsThis was an observational study based on a prospective registry of 122 consecutive mild SB patients (61.90 ± 18.28 years, 61.5% male, 57.88 ± 7.73 bpm) presenting with recurrent unexplained pre and syncope attacks admitted to our hospital for invasive electrophysiology study (EPS). Τhe implantation of a permanent antibradycardia pacemaker (ABP) was offered to all patients according to the results of the EPS. Eighty patients received the ABP, while 42 denied.ResultsThe mean of reported syncope episodes was 2.23 ± 1.29 (or presyncope 2.36 ± 1.20) in the last 12 months before they were referred for a combined EP guided diagnostic and therapeutic approach. Over a mean follow‐up of approximately 4 years (50.39 ± 32.40 months), the primary outcome event (syncope) occurred in 18 of 122 patients (14.8%), 6 of 80 (7.5%) in the ABP group as compared to 12 of 42 (28.6%) in the no pacemaker group (P = .002).ConclusionsAmong patients with mild degree of SB and a history of unexplained syncope, a set of positivity criteria for the presence of EPS defined SND after differentiating reflex syncope, identifies a subset of patients who will benefit from permanent pacing.

Abstract 14047: Novel Noninvasive Risk Stratification Method Using Control-and-stability-theory Applied to 12-lead-ECG Repolarization Patterns in Brugada Type1 Subjects

Background: Brugada syndrome (BrS) risk stratification in asymptomatic subjects and its underlying pathophysiological dynamics is complex. Purpose: This study aims to analyze, from alternative standpoints, superficial 12-lead ECG V2 repolarization patterns (repol.). This method diverges from ECG pattern characterization (patterns, angles, shapes, intervals, waves); it rather exploits nonlinear dynamics and stability of ECG repol. to assess stability driving cardiac dynamics: basal, after flecainide, during RF ablation, after 2nd flecainide test and post procedure. Target: to lower the number of invasive electrophysiology studies, furthering knowledge and applications of control-and-stability-theory applied to ECG. Methods: A stability control closed loop system has been designed to model electrophysiology dynamics of cardiac conduction: ECG segments being the input-output of the system. (Figure). A sequence of V2 repol. have been scanned, digitized and quantitatively processed yielding stability parameters (poles in S-plane). Scanning by Digitizeit - Digital River GmbH. S-plane computation by Microsoft Office, Wolfram Demonstrations Project & Contributors, https://demonstrations.wolfram.com Results: Figure. Conclusions: Based on our data, 1) 12-lead-ECG repol. are associated with increasing stability (parameter values b), denoting underlying nonlinear dynamics, trending to incremental stability from basal to end of procedure.2) The incremental stability associated with all the process phases, from basal to end of procedure, indicates a potential use of this methodology to BrS risk stratification. Unstable repol. may be classified as high VT risk. In conclusion, furthering control-and-stability-theory applied to 12-lead ECGs aims to deeper comprehension of physiological and pathological substrates of malignant arrhythmias, and to focus on noninvasive risk stratification strategies for ICD implantation indication in BrS.

Invasive electrophysiological studies in adult congenital heart disease- evolving use and impact of specialized centre therapy on recurrence of arrhythmia: a nationwird analysis based on 2.433 cases

Abstract Background Arrhythmias are a major contributor to morbidity and mortality in adult patients with congenital heart disease (ACHD). Advances in ablation technology have contributed to improved management and reduction of symptoms in this population. However, only limited data exist on the use and outcome of these technologies in large community-based cohorts of ACHD patients and on the impact of specialized centres on recurrence of arrhythmias. Purpose We performed a retrospective analysis based on data from one of the largest German Health Insurance Companies (approx. 9 million insured members), acquiring real-world data on frequency of invasive electrophysiological studies (EPS) in Germany between 2005 and 2018. ACHD patients were identified based on ICD codes and the spectrum of disease as well as the impact of EPS being performed at specialized ACHD centres was analysed. Results Out of 45,761 eligible ACHD patients in the database, we identified 2,433 EPS performed in 1,706 ACHD (51% female, median age 55.4 years, complexity of CHD mild, moderate and severe in 50.6%, 33.2%,16.2%, respectively). Over the study period the annual number of EPS increased by 207%. The majority of procedures were for supraventricular tachycardias (85.9%). Of these procedures atrial fibrillation accounted for 35.1%, atrial flutter for 29.4% and other supraventricular tachycardias/pre-excitation syndromes for 29.9% of cases. The majority of EPS (64.3%) was performed at non-specialized centres including 40.2% of cases in patients with complex disease. Overall, the re- intervention rate within 12 months of the primary EPS was 14.5%. Whereas in ACHD patients with simple and moderate complexity disease no obvious difference in 12-months re- intervention rate was observed between specialized and non-specialised centres (15.5% vs. 15.0%), in patients with complex disease the reintervention rate was 41.6% higher for non-specialized centres (13.6% vs. 9.6%). Conclusion Our large real- world analysis shows an increasing need for invasive electrophysiological studies in ACHD patients. The vast majority of procedures was performed for supraventricular arrhythmias including in atrial fibrillation and flutter ablation. Re-interventions were frequently required in this unique and anatomically challenging population. Alarmingly, many procedures were performed at non-specialized centres, although current guidelines recommend that interventions in complex patients should remain reserved for experienced high-volume centres. Funding Acknowledgement Type of funding source: None

Genome-wide association study of patients with atrioventricular nodal reentry tachycardia

Abstract Background Supraventricular tachycardias (SVTs) originate from the atria or the area close to the AV node. AV nodal reentry tachycardia (AVNRT) is one of the tachyarrhytmias comprising the group of SVTs. The typical patient is female, young at disease onset, with a structurally normal heart. At present we do not know the etiology of AVNRT. We therefore hypothesized that AVNRT might be caused by changes in the DNA. Methods DNA from purified blood was obtained from patients with AVNRT verified by an invasive electrophysiological study. Patients were recruited from five ablation centers in Denmark and individuals from the general population of Denmark (the BEFUS cohort) served as controls. DNA was subjected to chip genotyping, imputation and analyses in a genome-wide association study (GWAS) setup. Results A GWAS on 1,143 AVNRT patients and 3,004 controls revealed one locus close to the gene MYH6 to reach genome-wide significance for association with AVNRT (P=4.8x10–8). MYH6 encodes the α-isoform of the protein myosin heavy chain important for the contractile units of the heart, the sarcomeres. The gene is predominantly expressed in the atria. Additional subthreshold loci located close to other plausible arrhythmia genes were identified. Conclusion We report the first genetic locus to be associated with AVNRT close to the sarcomere gene MYH6. This is, to our knowledge, the first gene ever associated with AVNRT. Manhattan plot Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Rigshospitalets Forskningspulje - 3 years PhD salary

Big Data and Artificial Intelligence: Opportunities and Threats in Electrophysiology.

The combination of big data and artificial intelligence (AI) is having an increasing impact on the field of electrophysiology. Algorithms are created to improve the automated diagnosis of clinical ECGs or ambulatory rhythm devices. Furthermore, the use of AI during invasive electrophysiological studies or combining several diagnostic modalities into AI algorithms to aid diagnostics are being investigated. However, the clinical performance and applicability of created algorithms are yet unknown. In this narrative review, opportunities and threats of AI in the field of electrophysiology are described, mainly focusing on ECGs. Current opportunities are discussed with their potential clinical benefits as well as the challenges. Challenges in data acquisition, model performance, (external) validity, clinical implementation, algorithm interpretation as well as the ethical aspects of AI research are discussed. This article aims to guide clinicians in the evaluation of new AI applications for electrophysiology before their clinical implementation.

THE EFFECT OF ISOPROTERENOL USE ON ACCESSORY PATHWAY CONDUCTION CHARACTERISTICS IN WOLFF-PARKINSON-WHITE SYNDROME IN CHILDREN

Uncertainty remains regarding the utility of isoproterenol (ISO) testing for risk stratification in children with Wolff-Parkinson-White syndrome (WPW). We hypothesize ISO use during invasive electrophysiology study (EPS) would increase sensitivity and decrease specificity of identifying children who had a life-threatening event (LTE) in a large cohort of children with WPW.

Radiofrequency catheter ablation for supraventricular tachycardia in a paediatric population: characteristics of tachycardia mechanisms in a subpopulation with early onset.

In children, the first episode of supraventricular tachycardia occurs at various ages. The aim of this study is to describe age-specific tachycardia mechanisms, clinical findings, and outcome in a contemporary cohort of paediatric patients with supraventricular tachycardia. Retrospective analysis of 531 consecutive patients with structurally normal hearts under the age of 18 years who underwent invasive electrophysiological study for supraventricular tachycardia. The study population was divided into two groups, early-onset group (n = 57) and late-onset group (n = 474), according to the age of the occurrence of the first tachycardia before or after the age of 12 months. Accessory pathway-mediated tachycardia was more common (82.5 versus 50.1%, p < 0.001) and the proportion of left-sided accessory pathways was more pronounced (74.5 versus 53.7%, p = 0.01) in the early-onset group than in the late-onset group. The antegrade and retrograde refractory periods of the accessory pathways were similar in both groups, but pre-excitation was more common in the early-onset group (50.9 versus 31.9%, p = 0.007). Typical atrioventricular nodal re-entrant tachycardia was more common (36.7 versus 7.0%, p < 0.001) in the late-onset group. There was no difference among the two groups regarding overall outcome. Accessory pathway-mediated re-entrant tachycardia is the most common mechanism of recurrent supraventricular tachycardia in infants with structurally normal hearts who are later referred to an electrophysiological study. These pathways often cause pre-excitation and tend to be located on the left side whereas their refractory period is not different from that of patients with late-onset tachycardia.

State Institution «Romodanov Neurosurgery Institute of the National Academy of Medical Sciences of Ukraine» celebrates the 70th anniversary!

In 2020, State Institution “Romodanov Neurosurgery Institute of NAMS of Ukraine” occupies the glorious anniversary — 70 years since its foundation. By order of the Minister of Health of the USSR No. 439 of July 3, 1950, the structure and staffing of the Kyiv Research Institute of Neurosurgery were approved in the amount of 291 units. The regulations on the Institute were approved by the Ministry of Health of Ukraine on August 4, 1950.Departments of Neuro-oncology, Acute Trauma of the Central and Peripheral Nervous System, Neurovascular Pathology, Restorative Neurosurgery and Pediatric Neurosurgery were established in the structure of the Institute.The Neurosurgery Institute in different years was headed by: O.I. Arutiunov (1951–1964), A.P. Romodanov (1964–1993), Yu.P. Zozulia (1993–2013), E.G. Pedachenko (since February 2013).Today, the Institute’s clinical base consists of 15 specialized departments with 361 beds, where up to 7,000 patients are treated annually. In the out-patient department, from 30,000 to 40,000 patients receive counseling every year. In 15 operating rooms, more than 5,000 operations of the highest complexity are performed per year. Comprehensive examination and treatment of patients are provided by the scientific and diagnostic departments and laboratories.Currently, the Neurosurgery Institute staff amounts for 1,008 employees, including 38 doctors of medicine, 14 professors, and 80 candidates of sciences.Currently, the State Institution “Romodanov Neurosurgery Institute of NAMS of Ukraine” occupies a leading position in the diagnosing and treatment of neurosurgical pathology in Ukraine. The Institute has established and operates scientific schools on neurotrauma, neuro-oncology, vascular pathology of the brain and spinal cord, minimally invasive spinal neurosurgery, neurotransplantation, and neuroimmunology, which are headed and developed by leading specialists of the Institute. Throughout the existence of the Institute, training of scientific personnel is constantly carried out.The prospects for further development of the Neurosurgery Institute are intended in wide implementation of neuromodulation method, the development of gene therapy, the use of invasive electrophysiological studies and modern neuroimaging, the improvement and widespread adoption of endoscopic techniques in the neurosurgical practice, the development and implementation of methods of reconstructive neurosurgery and the treatment of chronic pain syndromes. It is extremely important for Ukraine to create a scientific and practical center for neurotrauma and a modern rehabilitation center on the basis of the Institute.

Noninvasive Localization of Accessory Pathways in Wolff–Parkinson–White Syndrome by Two-Dimensional Speckle Tracking Echocardiography

Background: Two-Dimensional Speckle Tracking Echocardiography (2D-STE) is a non-Doppler echocardiographic modality that allow quantification of myocardial deformity and its timing in 2D grey scale images, and was proved to be beneficial in assessment of dyssynchrony (STAR trial). Objective: To investigate the capability of 2D-STE for localizing Accessory Pathways (APs) in patients with Wolf-Parkinson-White (WPW) Syndrome. Patients and Methods: The prospective study included 15 patients with manifest AP indicated for invasive endocardial mapping and ablation. All patients were assessed by twelve-lead ECG, 2D-STE for the earliest activated site and invasive Electrophysiology study (EPs). Results: Out of the 15 patients with left-sided APs, 2D-STE was able to accurately localize the site of AP in 10 patents (66.6%), while electrocardiogram (ECG) was able to localize the site of AP in 12 patients (80%). Conclusion: 2D-STE has the ability to approximate the location of AP without the pitfalls of Doppler methods. However, ECG still more accurate and reproducible tool.

Defining Left Bundle Branch Block Patterns in Cardiac Resynchronisation Therapy: A Return to His Bundle Recordings.

Left bundle branch block (LBBB) is associated with improved outcome after cardiac resynchronisation therapy (CRT). One historical presumption of LBBB has been that the underlying pathophysiology involved diffuse disease throughout the distal conduction system. The ability to normalize wide QRS patterns with His bundle pacing (HBP) has called this notion into question. The determination of LBBB pattern is conventionally made by assessment of surface 12-lead ECGs and can include patients with and without conduction block, as assessed by invasive electrophysiology study (EPS). During a novel extension of the classical EPS to involve left-sided recordings, we found that conduction block associated with the LBBB pattern is most often proximal, usually within the left-sided His fibres, and these patients are the most likely to demonstrate QRS correction with HBP for resynchronisation. Patients with intact Purkinje activation and intraventricular conduction delay are less likely to benefit from HBP. Future EPS are required to determine the impact of newer approaches to conduction system pacing, including intraseptal or left ventricular septal pacing. Left-sided EPS has the potential to refine patient selection in CRT trials and may be used to physiologically phenotype distinct conduction patterns beyond LBBB pattern.

Loss of ventricular preexcitation during noninvasive testing does not exclude high-risk accessory pathways: A multicenter study of WPW in children

Abrupt loss of ventricular preexcitation on noninvasive evaluation, or nonpersistent preexcitation, in Wolff-Parkinson-White syndrome (WPW) is thought to indicate a low risk of life-threatening events. The purpose of this study was to compare accessory pathway (AP) characteristics and occurrences of sudden cardiac arrest (SCA) and rapidly conducted preexcited atrial fibrillation (RC-AF) in patients with nonpersistent and persistent preexcitation. Patients 21 years or younger with WPW and invasive electrophysiology study (EPS) data, SCA, or RC-AF were identified from multicenter databases. Nonpersistent preexcitation was defined as absence/sudden loss of preexcitation on electrocardiogram, Holter monitoring, or exercise stress test. RC-AF was defined as clinical preexcited atrial fibrillation with shortest preexcited R-R interval (SPERRI) ≤ 250 ms. AP effective refractory period (APERP), SPERRI at EPS , and shortest preexcited paced cycle length (SPPCL) were collected. High-risk APs were defined as APERP, SPERRI, or SPPCL ≤ 250 ms. Of 1589 patients, 244 (15%) had nonpersistent preexcitation and 1345 (85%) had persistent preexcitation. There were no differences in sex (58% vs 60% male; P=.49) or age (13.3±3.6 years vs 13.1±3.9 years; P=.43) between groups. Although APERP (344±76 ms vs 312±61 ms; P<.001) and SPPCL (394±123 ms vs 317±82 ms; P<.001) were longer in nonpersistent vs persistent preexcitation, there was no difference in SPERRI at EPS (331±71 ms vs 316±73 ms; P=.15). Nonpersistent preexcitation was associated with fewer high-risk APs (13% vs 23%; P<.001) than persistent preexcitation. Of 61 patients with SCA or RC-AF, 6 (10%) had nonpersistent preexcitation (3 SCA, 3 RC-AF). Nonpersistent preexcitation was associated with fewer high-risk APs, though it did not exclude the risk of SCA or RC-AF in children with WPW.

P969Improvement of left ventricular ejection fraction in the first week post rhythm restoration as a marker of long-term recovery of arrhythmia-induced cardiomyopathy in a latin american population

Abstract Introduction The incidence of Arrhythmia-Induced Cardiomyopathy (AIC) is presumed to be between 8% and 34%. Its outcome is also not well known and may be linked to multiple factors. However, it has been suggested that a 25% improvement of the Left Ventricular Ejection Fraction (LVEF), during the first week after rhythm restoration could be an indicator of long-term and complete recovery. This fact has not been studied in our country or even in Latin America. Purpose To observe the behavior of the LVEF after restoration of sinus rhythm in patients with systolic dysfunction presumably secondary to AIC, at least in one year of follow-up. Methods We evaluated all patients referred for arrhythmia treatment and having any degree of systolic dysfunction (LVEF less or equal to 50%) and functional class deterioration between January 2015 and September 2018. Restoration of sinus rhythm was accomplished in either by pharmacologic or invasive methods aimed to specific arrhythmias. After the treatment, we proceed with the systolic function evaluation starting one week after rhythm control, and then at one, three, six and twelve months. This evaluation consisted in clinical examination, echocardiographic determination of LVEF, as well as NT-ProBNP and troponin measurements. Results We identified twenty one cases with presumed AIC. Sixteen cases were secondary to atrial flutter, with four others being secondary to atrial fibrillation, and the last one being a consequence of frequent ventricular extrasystoles (VES). Fifteen patients (74%) were male, mean age was 51 years old (4-76 years). All cases of tachycardia had a ventricular rate over 100 beats per minute. The patient with VES, had a 58% burden of ectopic beats. Eighteen of these patients were taken to invasive electrophysiological study and radiofrequency ablation; and three patients received antiarrhythmics as rhythm control strategy. All patients had mid-range to severe systolic dysfunction prior to treatment, with a mean LVEF of 38%±7,5%; 63% of them were in NYHA class III-IV. One week after rhythm restoration, mean LVEF was 54± 6,36%. That was an improvement of 45% in LVEF. Mean LVEF at one and three months was 63± 5,43%, 61± 5,23% at six months and 63± 5,43% at one year. All patients improved their functional class, to NYHA I at the first evaluation post rhythm restoration. We found no differences between troponin and NT-ProBNP levels before and after treatment, except for one patient . Conclusion Appropriately treated AIC seems to have a good prognosis and short-term recovery of LVEF could be a useful indicator of complete normalization in the long-term. To our knowledge, here we detail the results of a relatively large time-series of AIC, and is perhaps the first study in the Latin American region that suggests that early LVEF improvement could predict AIC recovery, but controlled trials should be done in order to confirm these results.

797 Cardiac Invasive Electrophysiology Studies and Radiofrequency Catheter Ablation - Single Centre Experience

797 Cardiac Invasive Electrophysiology Studies and Radiofrequency Catheter Ablation - Single Centre Experience

Real Time Non-Invasive Hemodynamic Assessment of Ventricular Tachycardia

Hemodynamically unstable ventricular tachycardia (VT) is a critical cardiac arrhythmia associated with hemodynamic compromise that requires immediate cardioversion to prevent sudden cardiac death. Since unnecessary cardioverter defibrillators shocks damage the heart and increase the risk of mortality, the discrimination between unstable (i.e. requiring cardioversion) and stable (i.e. not requiring cardioversion) VT is of paramount importance. The aim of this study was to propose and assess non-invasive identification of hemodynamically unstable VT using photoplethysmography (PPG). Seventy-five (n = 75) episodes of VT were recorded in 14 patients undergoing invasive electrophysiological studies for VT catheter ablation. Invasive continuous arterial blood pressure (ABP), PPG and electrocardiogram (ECG) were simultaneously recorded. VTs were classified as unstable if during the first 10 seconds from onset, the mean ABP ( $\overline {P_{VT}}\mathrm { ) was $\overline {P_{VT}}\mathrm { mmHg or if $\text{P}_{\mathrm {VT}}$ dropped more than 30% with respect to a 10 seconds baseline (i.e. ratio $\text{R}_{\mathrm {ABP}} ). Five PPG morphological features were derived and compared to the heart rate from the ECG. PPG markers detected hemodynamically unstable VT with accuracy as high as 86% and were more accurate than the heart rate. The mean absolute slope was the best PPG parameter for classification of $\overline {P_{VT}}\mathrm { mmHg (AUC = 0.85, Sensitivity = 72%, Specificity = 86%) and $\text{R}_{\mathrm {ABP}} (AUC = 0.90, Sensitivity = 83%, Specificity = 89%) and it was automatically selected in the best two-variables logistic regression, for which AUC = 0.94. In conclusion, PPG analysis can accurately identify haemodynamically unstable VTs and has potential to enable optimization of VT therapy and reduce unnecessary and harmful cardioversion shocks.

005 Impact of Continuous Positive Airway Pressure on the Atrial Substrate in Patients With Obstructive Sleep Apnoea and Atrial Fibrillation: The SLEEP-AF Substrate Sub-Study

Obstructive sleep apnoea (OSA) is associated with an increasingly remodeled atrial substrate in atrial fibrillation (AF). Management of OSA has also been linked with improved management outcomes of AF. However, the impact of OSA management on the electrophysiologic atrial substrate has not been evaluated. To determine the impact of OSA management on the atrial substrate in AF. We recruited 24 consecutive patients having catheter ablation for AF with at least moderate OSA (AHI ≥15). Participants were randomised in a 1:1 ratio to receive continuous positive airway pressure (CPAP) or no therapy. At baseline, all participants underwent invasive electrophysiologic study comprising high density right atrial mapping and evaluation of effective refractory periods (ERP). After minimum of 6 months, the electrophysiologic protocol was repeated. Data was blinded and analysed offline. Outcome variables were atrial voltage (mV), conduction velocity (m/s), atrial surface area <1.5mV (%), atrial surface area <0.5mV (%), complex points (%) and atrial ERP (ms). There were no differences in baseline characteristics between groups and electrophysiologic parameters were comparable at baseline. Participants having CPAP were highly compliant (device usage: 79±19%, usage time: 268±91mins) resulting in significant AHI reduction (mean reduction: 31±23). There were no differences in blood pressure or body mass index between groups over time. The table presents data showing that CPAP results in marked reverse atrial remodelling. CPAP therapy results in reversal of atrial remodelling, providing mechanistic evidence advocating for management of OSA in AF.

Case of successful treatment of second-degree AV block in patient with gastroesophageal reflux disease associated with hiatal hernia

Clinical observation of a young patient without an organic pathology of the heart, who repeatedly sought medical help in connection with complaints of episodes of dizziness, lability of blood pressure and pulse numbers, is presented. The medical survey revealed a link between clinical symptoms and progressive retardation of AV conduction (from first-degree AV block to second-degree Mobitz II), and therefore the patient was recommended to be implanted with permanent artificial cardiac pacemaker. To clarify the nature of the conduction disorders, an invasive electrophysiology study was performed, which revealed a proximal AV block due to vagal influences. As the most likely cause of stimulation n. vagus was considered identified in a patient gastroesophageal reflux disease associated with hiatal hernia. Surgical treatment (laparoscopic fundoplication) led to a regression of the clinical and electrocardiographic picture, avoiding the implantation of permanent artificial cardiac pacemaker. The tactic chosen is consistent with the algorithm for managing patients with AV conduction abnormalities (2018 ACC / AHA / HRS Guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay), which involves eliminating potentially reversible causes of bradyarrhythmia before deciding whether to install permanent artificial cardiac pacemaker.

P5556Impact of viral genome detection in endo-myocardial biopsy of arrhythmogenic cardiomyopathy substrate

Abstract Background Arrhythmogenic cardiomyopathy (ACM) is a genetically inherited cardiomyopathy characterized by myocardial fibro-fatty replacement. A pathogenetic role of viral myocardial infections in ACM natural history has been proposed over the years, although no definitive conclusion has been reached yet. Purpose To describe viral genome presence into a cohort of ACM biopsy proven patients (pts) and its impact on clinical features and outcome. Methods A cohort of all ACM pts undergoing an invasive third level evaluation at our institution was enrolled. All pts underwent a cardiac magnetic resonance (MR), an invasive electrophysiological study (EPS) with endo-cavitary electro-anatomical mapping (EAM), and a EAM guided endo-myocardial biopsy (EMB). Viral genome research through molecular biology techniques was performed on all biopsied samples. According to arrhythmic risk evaluation, a trans-catheter ablation (TCA) and/or an internal cardioverter device (ICD) implant was performed. Clinical arrhythmic presentation, MR data, arrhythmia inducibility at EPS, EAM and EMB characteristic, and arrhythmic events at a 12-month follow up visit were retrieved in all pts and compared between the viral genome positive (v+ACM) and negative group (v-ACM). Results Forty-five pts were enrolled in our study (48±13 years; 66% male); the EMB samples of 7 (15%) pts presented a lymphocytic infiltrate and tested positive for viral genome (n=3 B19 Parvovirus; n=2 for Citomegalovirus; n=2 for Ebstein-Bar Virus) [Figure1]. At arrhythmic presentation, complex ventricular arrhythmias (NSVT, SVT and FV) were more frequent in the v+ACM group (86% vs 50%; p=0.039). Both left and right ventricular ejection fraction at MR resulted more depressed in the v+ACM group (44±7 vs 52±2 and 47±2 vs 52±2; p=0.047 and p=0.041). Complex ventricular arrhythmia inducibility at EPS was more frequent in v+ACM (72% vs 34%; p=0.032), while no differences in pathological potentials rate and extension at unipolar and bipolar EAM were found. TCA was performed in 55% and 57% and an ICD was implanted in 29% and 42% in the v+ACM and v-ACM group respectively. No differences in 12-months arrhythmic event rates (39% vs 42%) between the two groups were described. EBM at different magnifications/stains Conclusion In our cohort a viral infection super-imposed to the fibrofatty infiltration was found in 15% of the patients. ACM pts testing positive for viral genome at the EMB had a more severe arrhythmic disease presentation, a more impaired heart function, and a higher rate of complex ventricular arrhythmias at disease presentation, but seemed to respond as well as viral genome negative ACM to ablative and pharmacological treatment

P5690Comparison of two methods to navigate the stereotactic body radiotherapy ablation for ventricular tachycardia, the invasive electrophysiological study and substrate identification

Abstract Purpose To compare two methods used for identifying the arrhythmogenic substrate - invasive electrophysiological study versus PET-CT scar identification. The substrate is then targeted by stereotactic body radiotherapy (SBRT) in patients with previously unsuccessful radiofrequency catheter ablation. Methodology Patients with ischemic cardiomyopathy, LVEF less than 40% and unsuccessful conventional treatment resulting in recurring ventricular tachycardias, were divided into two groups with different methods of obtaining arrhythmogenic substrate. In the group A, invasive electrophysiological mapping was used, while in the group B, scar identification by PET-CT was done, enhanced with non-invasive body surface ecg mapping of all inducible ventricular tachycardias. This target obtained was then attacked with SBRT. We compared the size of the planned target volume (PVT), the SBRT duration, the calculated dose for the esophagus, stomach and lung and the incidence of acute complications. Cohort description Patients in group A were recruited from April 2014 to December 2018, patients in group B from June to December 2018. Group A (8 patients) – mean age 66, NYHA class 2.4, LVEF 29,4%. Group B (6 patients) – mean age 71, NYHA class 2.1, LVEF 25,2%. All patients were men. Results There was a statistically significant difference in PTV – Group A (mean 24.1ml, SD = 3,9), Group B (mean 76.0ml, SD 14.1), p&lt;0,001 (two-sample t-test). There was no difference in the calculated secondary radiation doses acquired by surrounding organs. The most frequent adverse event was acute anorexia, occurring in 4 patients from Group A and in 2 patients from Group B. The anorexia subsided in one week time. One patient from Group B suffered from esophageal ulcer, which developed 6 months after the therapy. Conclusion Using invasive electrophysiology mapping to identify arrhythmogenic substrate for SBRT yields significantly smaller volume of targeted tissue. Despite this finding, we did not find any difference neither in radiation dose delivered to the surrounding organs, nor in the radiation duration.

Wolff-Parkinson-White pattern and risk of sudden death

In this volume of The Journal, Chubb et al report the results of a survey of pediatric cardiac electrophysiologists on the management of patients identified with the Wolff-Parkinson-White (WPW) pattern on electrocardiogram (ECG) with no symptoms. They report that many electrophysiologists are being more aggressive about using invasive electrophysiology studies with subsequent ablation as treatment than the most current guidelines would suggest. The reason this discussion is important for all pediatricians to understand is that recent studies have suggested that pediatric patients with asymptomatic WPW are at substantially higher risk of sudden death than adults with WPW. Studies have also shown that evaluating risk of sudden death using non-invasive approaches is challenging at best. Thus, when pediatric patients with asymptomatic WPW are identified, it is important for them to be referred to a pediatric electrophysiologist for further evaluation and possible ablation of the accessory conduction pathway. Article page 88▸ Management of Asymptomatic Wolff-Parkinson-White Pattern by Pediatric ElectrophysiologistsThe Journal of PediatricsVol. 213PreviewTo determine the present-day approach of pediatric cardiac electrophysiologists to asymptomatic Wolff-Parkinson-White (WPW) pattern and to contrast to both published consensus statements and a similar survey. Full-Text PDF

Diagnostic evaluation and arrhythmia mechanisms in survivors of unexplained cardiac arrest.

Identifying the cause of unexplained cardiac arrest is critical for appropriate management of both survivors and their family members. Aborted cardiac arrests whose cause remains unknown following investigation with a surface ECG, echocardiogram, and coronary angiogram are deemed unexplained. Many of these unexplained arrests are felt to be secondary to concealed forms of cardiac channelopathies and latent or subtle cardiomyopathies. This recognition has led to evaluating a diagnostic role for a series of additional investigations, including advanced imaging, genetic testing, and provocative forms of testing, including sodium channel blockade and treadmill testing. Despite evidence of an improved diagnostic yield through their systematic usage, clinical guidelines have yet to endorse a formal algorithm delineating investigations that must be performed before assigning a label of idiopathic ventricular fibrillation, which has resulted in markedly variables thresholds for concluding this diagnosis. Debate remains regarding the need for an invasive electrophysiology study among these patients, though identification of arrhythmic culprits requiring intracardiac electrograms for diagnostic confirmation have suggested a potential role when an initial comprehensive evaluation is unrevealing. Although progress is being made, the sizeable portion of arrests that remain unexplained despite completion of a comprehensive evaluation highlights an ongoing need for further research and additional tools to help unravel the ongoing mysteries of these near fatal events.