Recurrent ICD Research Articles

Ablation of right ventricular endocavitary arrhythmias

Abstract Background The right ventricular moderator band-papillary muscle (RV MB-PM) complex has a rich subendocardial network of purkinje fibers which can lead to ventricular arrhythmias (VA)1. Catheter ablation of such arrhythmias is procedurally challenging and there remains limited studies on long-term procedural success. Purpose We aimed to systematically study RV MB-PM complex VA. Methods A single center retrospective study from January 2013 to December 2023 identified 3249 patients who underwent VA ablation. The RV MB-PM complex was targeted in 47 patients. Acute success was defined as suppression of the targeted VA >=30 minutes post ablation. Long-term success was defined as the absence of symptoms, total PVC burden <5% or improvement in EF in patients presenting with isolated PVCs and as freedom from appropriate ICD therapy in patients presenting with malignant PVCs inducing VF, sustained VT or VT storm. Results Mean age was 51.9 ± 16.7 years and 64% were male. 40 (85%) patients had VA targeted from the MB and 7 (15%) from the PM complex (2 anterior, 2 inferior and 3 septal PM). 34 (72%) had no underlying structural heart disease, 3 (6%) ischemic cardiomyopathy and 10 (21%) non-ischemic cardiomyopathy. No patient had delayed gadolinium enhancement in the RV MB-PM complex. VA were inducible in 42 (89%) of patients and activation mapping was used in 9 (19%), pace mapping in 5 (11%) and a combination of activation and pace mapping used in 33 (70%) patients. Intracardiac echocardiography was used in all cases. Pre-QRS duration was 34.0 ± 10.4 ms. Radiofrequency ablation was used in 37 (78.7%) cases, cryotherapy in 4 (8.51%) cases and a combination of the 2 energy sources in 6 (12.8%) cases. In all cases, acute peri-procedural success was achieved. 24 (51.1%) patients presented with isolated PVCs and were followed up for 4.72 ± 3.55 years after their index procedure. 3 patients underwent repeat catheter ablation targeting the same PVC focus but all patients had long term success with a PVC burden of 16.1 ± 12.5% prior to ablation and 2.40 ± 2.44% at last follow-up. 16 patients underwent ablation for recurrent ICD shocks after initially presenting with PVC induced VF. Patients were followed up for 3.22 ± 2.09 years and 14 (88%) patients remained free from ICD therapy. 7 patients had MB ablation for sustained VT and were followed up for 4.06 ± 3.77 years. 5 (71%) patients remained free from ICD therapy. A purkinje potential was seen in 8% (2/24) cases of isolated PVCs and in 39% (9/23) cases of PVC induced VF or VT (p=0.13). Conclusions RV MB-PM VA commonly present with malignant VF and a purkinje potential is more likely to be seen in these cases suggesting different VA mechanisms to isolated PVCs and catheter ablation is an effective long-term strategy.

Risk factors for first and recurrent ICD therapy in primary and secondary prevention patients with an implantable cardioverter defibrillator

Abstract Introduction Implantable cardioverter-defibrillators (ICD) are used to prevent sudden cardiac death in patients with elevated risk of life-threatening arrhythmia. Medical treatment of heart disease and the population of ICD carriers have changed since the pivotal studies 20 years ago, sparking a need for improved ICD candidate selection and identification of risk factors for ICD therapy. Purpose This study aimed to examine risk factors associated with incident and recurrent ICD shock. Methods This single-center, prospective registry-based study examined patients with ICD for primary or secondary prevention (PP, SP) implanted between January 2010 and January 2020. Outcomes were appropriate (ADC) and inappropriate (IADC) ICD shock. Supplementary analyses for the risks of recurrent shock were conducted if incident therapy occurred. Results Overall, 2997 patients were analyzed (median follow-up 6.5 years, mean age 63.8 years±12.7, 20% female, 27% CRT-D carriers and 47.8 % SP). A total of 386(13%) and 85(2.8%) experienced ADC and IADC, respectively and 143(37%) and 17(20%) recurrent therapies, respectively. Event rates were 2.6(2.4-2.9) [PP 1.7 (1.4-2.0); SP 3.7(3.3-4.2)] and 0.5 (0.4-0.7) [PP 0.4(0.2-0.5); SP 0.7(0.5-0.9)] per 100 person-years for incident ADC and IADC, respectively. For recurrent ADC and IADC, event rates were 14.6(12.3-17.2) [PP 14.1(10.1-19.2); SP 14.7(11.9-17.8)] and 2.9(1.3-5.4) [PP 2.6(0.5-7.7); SP 3.0(1.1-6.6)], respectively. Figure 1 shows cumulative incidences for PP and SP. Females had a lower risk of incident ADC (HR 0.68 [95% CI 0.50;0.92] p=0.01) overall and when SP (HR 0.66 [95% CI 0.45;0.97] p=0.04), as did CRT-D overall (HR 0.60 [95% CI 0.45;0.82] p=0.001) and in SP (HR 0.42 [95% CI 0.24;0.74] p=0.003). Previous revascularization was associated with a lower risk of incident IADC (HR 0.58 [95% CI 0.36;0.94] p=0.03) overall and in SP (HR 0.51 [95% CI 0.28;0.93] p=0.03). Left ventricular ejection fraction (LVEF) <35 and BMI >30 in SP patients were associated with increased risk of incident ADC and IADC respectively (HR 1.38 [95% CI 1.04;1.84] p=0.03) and HR 2.48 [95% CI 1.16;5.32] p=0.02). Association with higher risk of recurrent ADC was only seen in BMI <18.5 for SP patients (HR 87.37 [95% CI 8.43;905.72] p<0.001), no associations for recurrent IADC were observed. No interactions between SP/PP and risk factors, except for BMI>30 on IADC (p for interaction=0.01) occurred. PP (HR 0.38 [95% CI 0.16;0.89] p=0.02) and SP (HR 1.77 [95% CI 1.04;3.03] p=0.03). Conclusion This large single-center study found higher rates of incident and recurrent ICD shock in SP versus PP. Female sex and CRT-D were associated with lower risk of ADC, previous revascularization with increased risk of IADC. BMI>30 and reduced LVEF were associated with increased risk of incident ADC and IADC respectively. Further contemporary studies are needed to cast light on the clinical implications of risk factors.

Stellate Ganglion Ablation by Conventional Radiofrequency in patients with Electrical Storm.

We report a series of patients with Electrical Storm (ES) who underwent bilateral stellate ganglion ablation by using conventional radio frequency (RFA). The procedure was done with fluoroscopic guidance using the COSMAN™ 1A RF Generator and a 22G RF needle (5 cm length and 5 mm active tip). Six patients, four male and two female (mean age 55 ± 7 years and mean LVEF-42 ± 21%) with ES underwent the procedure under fluoroscopic guidance. All patients experienced recurrent ICD shocks or required multiple external defibrillation shocks. There were no procedural complications. All patients survived free of ES at discharge. At a mean follow-up of 22 ± 8months, all were alive free of ES but two patients received appropriate shocks for VT and one patient had VT terminated by ATP. This small series of cases is a proof of concept that neuromodulation by conventional RFA targeting bilateral stellate ganglia appears safe, feasible, and effective in treating selected unstable patients with ES.

Long-term success of a multi-electrode substrate mapping and ablation strategy versus a classic single tip mapping and ablation strategy for ventricular tachycardia ablation in patients with ischemic cardiomyopathy.

Over the past years, mapping and ablation techniques for the treatment of ventricular tachycardia (VT) have evolved rapidly. High Density (HD) substrate mapping is now routine and pre-procedural imaging is increasingly used. The additional value of these techniques for long-term VT-free survival is not clear. We compared baseline and procedural characteristics, procedural success, safety and outcome of mapping and ablation of ventricular tachycardia in patients with ischemic heart disease between two groups. (1) Low Density (LD) group: VT mapping and ablation with a 4mm single tip catheter (2) HD group: HD substrate mapping with the Pentaray (Biosense Webster, USA) or HD Grid (Abbott, USA) catheter and ablation with a 4mm single tip catheter. VT ablation was performed in 133 patients (71 patients in LD group and 62 patients in HD group). The median follow-up was 5.0 years in LD group and 2.0 years in HD group. One-, two-, and five-year VT recurrence rates were 47%, 56%, and 65% in the LD group versus 39%, 50%, and 55% in the HD group (log-rank test for VT recurrence p=.70). One-, two-, and five-year ICD shock recurrence rates were 14%, 18%, and 24% in the LD group versus 8%, 15%, and 19% in the HD group (log-rank test for ICD-shock p=.79). All-cause mortality, cardiac (non-arrhythmic), and arrhythmic death, were similar in both groups. Severe procedural complications (tamponade, stroke, or procedural death) occurred in four patients (5%, 1 vascular, 3 tamponade) in the LD group versus two patients (3%, both tamponade) in the HD group (NS). In univariate and multivariable analysis, only a higher LVEF was significantly associated with VT-free survival. HD mapping was not significantly associated with VT-free survival. Anterior infarct location and age were significantly associated with ICD recurrent shock in both univariate and multivariable analyses. In patients with ischemic cardiomyopathy, a HD substrate mapping, and ablation strategy did not lead to higher VT-free survival and shock-free survival compared to a single tip mapping and ablation strategy. In this study, only LVF is an independent predictor for VT recurrence. Anterior infarct location and age predict recurrent ICD shocks.

Prognosis of patients undergoing catheter ablation of arrhythmic storm in patients with and without history of previous ICD interventions

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation (CA) improves prognosis in patients with electrical storm (ES). However, its effectiveness and timing in patients with ventricular tachycardia and appropriate ICD therapies remain a matter of debate. Purpose Our aim was to investigate whether patients with history of discrete ventricular tachycardia episodes had different clinical features and outcome compared to patients with ES as first arrhythmic occurrence. Methods We enrolled 57 consecutive patients undergoing CA for ES and collected clinical, echocardiographic and electroanatomic mapping data. The primary end point was a composite of death from any cause and recurrences of sustained VT or ventricular fibrillation, appropriate ICD therapy, or ES. Results During a median follow up of 39 months, 28 patients (49%) met the primary end point of arrhythmic recurrence or death from any cause. There were no significant differences between clinical, electrocardiographic and echocardiographic parameters in the two groups. Regarding ICD therapies, patients with who met the primary end point had a higher number of ATP/shock episodes preceding the ES event: 15 (52%) vs 25 (89%), p=0.002. At Cox regression analysis, NIDCM, previous ATP and/or shock and ≥3 ATP were associated with arrhythmic recurrences and/or death. At multivariate analysis, ≥3 ATP was the only predictor that met statistical significance for the primary end point: HR was 30.41, CI 4.42 – 209.12, p=0.001. When dividing our population in patients and without ventricular arrhythmias (VAs) with appropriate device intervention before ES, thoses with VAs arrhythmias before ES had a higher percentage of presence of late potentials (80% vs 55%, p=0.041) and a greater unipolar scar (59.2±41.6 vs 30.2±21.6, p=0.001). At univariate analysis the presence of late potentials was associated with ventricular arrhythmias before ES (OR 3.33, CI 1.03-10.84, p=0.045). Conclusions CA in patients with a long arrhythmia history, recurrent ICD therapies and presence of late potentials at electroanatomic mapping, may yield worse outcomes and therefore our results support an early referral for CA of VT to improve prognosis in these subjects.

PO-03-145 BETA BLOCKERS IN PATIENTS WITH LONG QT SYNDROME: MOVING AWAY FROM ONE-SIZE-FITS-ALL?

Experts in the field recommend using nadolol at 1mg/kg/day and propranolol at 2-3mg/kg/day for patients with long QT syndrome (LQTS), but there are no available studies defining the most effective dose. In our experience, most but not all patients tolerate beta blocker at full dose. To describe our institutional experience with utilizing exercise stress testing (EST) in the subset of LQTS patients who did not tolerate standard beta-blocker dosing. We queried our Inherited Arrhythmia Registry and identified patients with LQTS who were on "submaximal" nadolol/propranolol doses (defined as < 1mg/kg/day for nadolol and < 2mg/kg/day for propranolol) and who had at least one follow up appointment. For those patients, we have devised a practical approach for demonstrating sufficient beta blockade effect by assessing for heart rate (HR) blunting at maximal exercise, which was defined as at least 15-20% decrease from maximal HR. Of 166 patients with LQTS, 51 (53% females, 53% probands) were on “submaximal” beta blocker therapy at time of last follow up and formed our study cohort. Median age at diagnosis and QTc were 15.8 yrs (range: 0.1-50.9 yrs) and 484 ms (400-610 ms) respectively. In terms of LQTS type: 24 had LQT1, 22 had LQT2, 2 had LQT5, 1 had LQT1 + LQT2, 1 had LQT3, and 1 patient had a VUS in CALM3 gene. Cardiac events included: cardiac arrest in 4 (8%) prompting ICD implantation, bradycardia-induced Torsades de Pointes in 2 (4%) prompting pacemaker implantation, recurrent cardiac syncope prompting sympathectomy in 2 (4%) and cardiac syncope in 10 (20%). The distribution of beta blocker dose is shown in Figure 1A and % predicted peak HR on EST as a function of beta blocker dose is shown in Figure 1B. EST data was available in 37 (73%) patients and demonstrated that HR blunting can be achieved with “submaximal” doses. Over a median follow up of 6.3 years and while on intentional “submaximal” beta blocker therapy, 1 (2%) patient had recurrent appropriate ICD shocks prompting referral for sympathectomy, and no patient (0/34, 0%) with adequate HR blunting had a cardiac event. In our institutional LQTS experience, adequate heart rate blunting may be achieved with "submaximal" beta blocker dose. EST may be a useful modality to devise an individualized treatment plan and titrate beta blocker dose to effect, especially in those that cannot tolerate the recommended guideline directed dose.

PO-04-185 SAFETY AND EFFICACY OF BEDSIDE ULTRASOUND-GUIDED SYMPATHETIC BLOCKADE BY PROXIMAL INTERCOSTAL BLOCK IN PATIENTS WITH ELECTRICAL STORM

Electrical storm (ES) patients (pts) who fail standard therapies have a high mortality rate. Previous studies report effective management of ES with bedside, ultrasound-guided percutaneous stellate ganglion block (SGB) as single injection or continuous infusion of local anesthetics. SGB can be technically challenging by the presence of other catheters and support devices in the anatomical area. We report our experience with sympathetic blockade administered by the regional anesthesiology team via the alternative proximal intercostal block (PICB) (Figure 1A-C). This technique targets an area typically free of catheters and support devices, and may pose less strict requirements for anticoagulation interruption, along with lower risk of focal neurologic side effects. To describe safety and efficacy of PICB in patients with refractory ES. We reviewed our institutional data on ES pts who underwent PICB between 1/2019-10/2022 to analyze procedural safety, short and long-term outcome. Total of 12 pts with ES underwent PICB during this period (Table 1). Five pts initially had left SGB, but 2/5 required PICB due to need for prolonged infusion and rotating site of infusion catheter. Three pts underwent PICB due to lack of efficacy of SGB alone. Sympathetic blockade efficacy appeared higher when left SGB was combined with PICB with response rate of 71.4%. Among ten pts who presented with recurrent ICD shocks (Figure 1D), nine had no further ICD shock after PICB until discharge, heart transplant, or death (P=0.01). There was no procedure-related complication or focal neurologic symptoms. Overall, 8 (66.7%) pts had VT ablation, 9 (75%) pts survived to discharge, 2 (16.7%) pts underwent heart transplantation, 1 (8.4%) patient had ventricular assist device implanted as a bridge to transplant, and 2 (16.7%) pts died. During median of 168 +/- 148.5 days follow up on those pts who survived to discharge without heart transplant, 71.4% remain free of any VT recurrence. In patients with refractory ES, continuous PICB provided safe and effective sympathetic block with no incidence of block-related focal neurologic symptoms. In our series, overall PICB efficacy was 66.7% and the combination of PICB and left SGB appeared complementary. The potential benefits of bilateral sympathetic blocks or block combinations should be carefully weighed against patient- and technique-specific risks and side effects. Larger studies are needed to compare these treatment techniques.

Abstract 13833: Cardiac Sympathetic Denervation in Patients With Ventricular Tachycardia or Electrical Storm: A 6 Months Follow-Up

Introduction: Cardiac sympathetic denervation (CSD) is considered in the management of patients with refractory ventricular arrhythmias or storm. It has been shown to decrease the burden of ventricular arrhythmias and the ICD shocks acutely in previous studies, however, follow-up data is still limited. Hypothesis: The purpose of this study is to evaluate ventricular tachycardia (VT) recurrence within a 6-month period after CSD. Methods: We analyzed all patients who underwent CSD at the University of Florida hospital between 2011 to 2017. The primary outcome was the recurrence of sustained VT at 6 months. The burden of ICD shocks, the need for VT ablation/redo ablation, and cardiovascular-related mortality in the first 6 months were also reported. Results: A total of 29 patients with CSD were included (9 patients had left CSD and 20 patients had bilateral CSD, mean age 60.1±11.5, 86 % male, and EF 27.3±15.4% by 2D-echocardiography), 13 (44.8%) of them presented with VT storm and 15 (51.7%) had prior VT ablation. One patient had cardiovascular-related mortality by 1 month and 7 patients by 6 months. The rate of VT recurrence was 31% by 1 month and increased to 35% by 6 months. By the end of the follow-up period, 17 (58.6%) patients remained free of recurrent ICD shocks and VT ablation was needed in 12 (41.4%) patients, 6 of them were redo-ablations. We further divided patients based on the underlying heart disease including ischemic heart disease (HD) and non-ischemic HD and there was no difference in the rate of VT recurrence at 6 months (p=0.18). There was also no difference in the primary outcome between left only CSD and bilateral CSD (P=0.98). Conclusions: Our data show that CSD showed benefit in VT recurrence rate at 6 months post-procedure. Reduction and freedom of ICD shocks were noted in patients with refractory VT or electrical storm. These benefits were independent of the underlying heart disease etiology. More studies with a longer follow-up period are warranted to confirm these results and follow long-term outcomes.

Real-world evaluation of follow up strategies after implantable cardiac-defibrillator therapies in patients with ventricular tachycardia (REFINE-VT)

Abstract Introduction Implantable cardiac-defibrillators (ICD) can prevent sudden cardiac death but the risk of recurrent ventricular arrhythmia (VA) and ICD therapies persists. Established strategies to minimize such risks include medication optimization, device reprogramming or ventricular tachycardia (VT) catheter ablation (CA). However, the timing and choice of these strategies at ICD follow-up may not be as consistent in the real-world as the regulated conditions of clinical trials. Furthermore, whether these decisions at follow-up are influenced by the type of arrhythmia, ICD therapy or patient characteristics remain unclear. Purpose We evaluated ICD follow-up strategies in patients with ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM) to refine the outpatient management of these complex patients and ultimately improve overall patient outcome. Methods REFINE-VT is a retrospective study of 514 patients with ICD/CRT-D who attended ICD follow-up between June 2018 to September 2019 at the University Hospital Coventry &amp; Warwickshire (UHCW) tertiary cardiology department. All follow-ups were face-to-face. Patients were divided into 2 groups according to the absence or presence of sustained VA (e.g. &amp;gt;30 seconds of VT and/or appropriate ICD therapy), described as “negative event” and “positive event” groups respectively. The type of strategy employed in response to a positive event were categorized into 4 groups: (1) Medication change only (2) Device programming +/− medication (3) Referral for VT CA (4) No intervention Results 514 consecutive patients with ICD (52%) or CRT-D (48%) were analysed. Overall mean age was 67±14 years with 79% male patients. ICM was diagnosed in 329 (64%) patient and NICM in 185 (36%). 437 (85%) patients had no significant VA and/or ICD therapy referred to as the negative group. A total of 77 patients (15%) suffered VA and/or ICD therapies, of whom 22 patients (26%) experienced a second event. 31% (n=24) of this positive event group received no preventative strategy (Table 1). We observed an inconsistent approach to the choice of strategies across different types of arrhythmias and ICD therapies. E.g. the odds of intervening were significantly higher if ICD shock was detected compared to anti-tachycardia pacing (OR 8.4, 95% CI 1.7–39.6, p=0.007). Even in patients with two events, the rate of referral for VT ablation and escalation of antiarrhythmics were similarly as low as patients with a single event (Table 2). Conclusion This is the first contemporary study that has evaluated how strategies that reduce the risk of recurrent ICD events are executed in a real-world population. We have demonstrated that the decision to intervene and choices of strategy remain inconsistent and partially biased by the type of arrhythmia and ICD therapy at follow-up. This supports the need for an evidence-driven multi-disciplinary VT clinic to refine and standardize our approach to this heterogeneous population. Funding Acknowledgement Type of funding sources: None.

NON-INVASIVE CARDIAC RADIOABLATION FOR RECURRENT VENTRICULAR TACHYCARDIA: INITIAL RESULTS AND INSIGHTS

<h3>BACKGROUND</h3> Non invasive cardiac radio-ablation (RA) has emerged as an alternative to escalating anti arrhythmic drugs (AADs) in patients who are unwilling or unable to undergo catheter ablation (CA) for recurrent ventricular tachycardia (VT). We present our initial experience of treating 9 patients on a compassionate use basis and offer insights into programme development and delivery in Canada. <h3>METHODS AND RESULTS</h3> Twenty four patients have been referred to the programme since August 2019. We have treated 9 patients with RA as 12 patients declined and another three underwent emergent CA for VT storm. Of the 15 patients who did not receive RA, 10 are now deceased (67%). Following RA one patient (11%) deceased at 11 months due to respiratory infection. Although highly selective, clinical characteristics between those receiving and not receiving RA are similar. Patients undergoing RA are medically stabilised and receive echo, CT and PET scanning similar to patients undergoing CA. All 9 patients underwent non invasive EP study (NIPS) under light sedation administered by a single IV cannula without complication. VT is induced using the ICD in situ and mapped using the CardioInsight ECGi system. Targets for RA are identified combining the ECGi data with the contemporaneous imaging data. This analogue process involves Cardiac EP/ Imaging, Radiation Oncologists and Medical Physicists. The median time to RA from NIPS is 12 working days (IQR 8, 20). A single fraction of 25 Gy is targeted using 4D-CT with an average on beam time of 15 minutes. All patients receive Rivaroxaban 20 mg for thirty days post RA. Thus far 1 patient (11%) has suffered pneumonitis requiring a 4 week course of oral corticosteroids, but there have been no other adverse events attributable to RA. Post RA 8 patients (89%) experienced an immediate reduction in VT burden as recorded by their ICD. As compared to the 6 months prior to RA, there was a greater than 90% reduction in VT requiring ICD therapy (ATP or shocks) and at 9 months only 1 patient (11%) has suffered recurrent ICD shocks. The majority of patients (67%) have had antiarrhythmic drug therapy reduced or withdrawn post RA. <h3>CONCLUSION</h3> Non invasive cardiac radioablation appears safe, well tolerated and effective in the short term for those unwilling or unable to receive catheter ablation for recurrent VT. Several opportunities remain to improve logistics, targeting and availability of the procedure to improve outcomes for this cohort of patients in Canada.

B-PO03-183 SURVIVAL FOLLOWING THORACOSCOPIC SYMPATHECTOMY FOR REFRACTORY VENTRICULAR TACHYCARDIA

Several studies have reported ventricular tachycardia (VT) outcomes after thoracoscopic sympathectomy (TS) for refractory VT. However, less is known about overall survival following TS. To assess survival following TS for refractory VT. We retrospectively evaluated all patients with a previously implanted ICD that underwent at least one TS for the treatment of refractory VT at Emory Healthcare between February 2015 and April 2020. Baseline characteristics and clinical outcomes were evaluated by chart review. The primary endpoint was overall survival and the secondary endpoint was survival free of recurrent ICD shocks. We identified 41 patients with a mean age of 60.7 ± 13.5 years, of which 33 (80.5%) were male. Thirty-six patients (87%) had bilateral sympathectomy. Twelve (29.3%) patients had ischemic heart failure (CHF) and 21 (51.2%) with non-ischemic CHF. They had failed on average 2.15 ± 1.01 antiarrhythmics. Thirty-two (78%) patients underwent unsuccessful VT ablation with an average of 1.52 ± 0.89 attempts. Mean duration of follow-up was 39.3 ± 4.3 months. Overall survival at 36 months post-TS was 75.6% (Figure). Recurrent ICD shocks occurred in 46.3% at 12 months after TS. Mean shock-free survival was 11.4 ± 2.18 months. Survival at 3 years following thoracic sympathectomy for refractory VT was 75.6%, with 46.3% recurrent ICD shocks at 12 months. These data suggest that TS is a safe adjunct to refractory VT management in this challenging group of patients.

Expert consensus on acute management of ventricular arrhythmias - VT network Austria.

The Arrhythmia Working Group of the Austrian Society of Cardiology (ÖKG) has set the goal of systematically structuring and organizing the acute care of patients with ventricular arrhythmias (VA), i.e. ventricular tachycardia (VT) or ventricular fibrillation (VF) in Austria. Within a consensus paper, national recommendations on the basic diagnostic work-up of VA (12-lead ECG, medical history, family history, laboratory analyses, echocardiography, search for reversible causes, ICD interrogation), as well as further medical treatment and therapeutic measures (indication of coronary angiography, ablation therapy) are established.Since acute ablation of VT is indicated in the current ESC guidelines as a class IB indication for scar-associated incessant VT or electrical storm (ES; ≥ 3 ICD therapies in 24 h) as well as for ischemic cardiomyopathy (iCMP) with recurrent ICD shocks, organizational measures must be taken to ensure that these guidelines can be implemented. Therefore, a VT network will be established covering all areas in Austria, consisting of primary and secondary VT centers. Organizational aspects of an acute VT network are defined and should subsequently be implemented by the participating hospitals. All electrophysiologic centers in Austria that deal with VT ablation are to be integrated into the network in the medium-term. Centers that co-operate in the network are divided into primary and secondary VT centers according to predefined criteria.

The Role of Ablation in Prevention of Recurrent Implantable Cardioverter Defibrillator Shocks in Patients With Tetralogy of Fallot

BackgroundImplantable cardioverter defibrillators (ICDs) are effective in preventing arrhythmic sudden cardiac death in patients with tetralogy of Fallot (TOF). Although ICD therapies for malignant ventricular arrhythmias can be life-saving, shocks could have deleterious consequences. Substrate-based ablation therapy has become the standard of care to prevent recurrent ICD shocks in patients with ischemic cardiomyopathy. However, the efficacy and safety of this invasive therapy in the prevention of recurrent ICD shocks in patients with TOF has not been well evaluated. MethodsRecords of a total of 47 consecutive TOF patients (mean age: 43.1 ± 13.2 years, male sex: n = 34 [72.3%]) who underwent ICD implantation for secondary prevention between 2000 and 2018 were reviewed. ResultsTwenty (42.6%) patients underwent invasive therapy (radiofrequency catheter ablation, n = 8; surgical ablation with pulmonary valve replacement, n = 12) before ICD implantation. Twenty-seven patients (57.4%) were managed noninvasively. During follow-up (median 80.5 [interquartile range, 28.5-131.0] months), 2 (10.0%) patients in the invasive group and 10 (37.0%) patients in the noninvasive group received appropriate ICD shocks (P = 0.036). Logistic regression analysis showed that invasive therapy was associated with a decreased risk of ICD shocks by 81.1% (odds ratio, 0.189; 95% confidence interval, 0.036-0.990; P = 0.049). Furthermore, invasive therapy was associated with decreased risk of the composite outcomes of ICD shock, death, cardiac transplantation, and hospital admission (odds ratio, 0.090; 95% confidence interval, 0.025-0.365; P = 0.013) compared with noninvasive therapy. ConclusionsInvasive substrate modification therapy was associated with a lower likelihood of ICD shocks and improvement of long-term outcomes in TOF patients.

Just the facts: management of electrical storm and recurrent ICD shocks in the emergency department.

Just the facts: management of electrical storm and recurrent ICD shocks in the emergency department.

LEFT SYMPATHETIC GANGLIONECTOMY FOR REFRACTORY PRIMARY VENTRICULAR FIBRILLATION ARREST OF UNKNOWN ETIOLOGY IN A YOUNG MALE

Patients with primary ventricular fibrillation (VF) sometimes suffer from refractory VF. Recurrent ICD shocks secondary to refractory VF cause anxiety and reduce quality of life, especially in young adults. Although many case reports in literature have described the benefit of left cardiac

P5689First intention epicardial VT ablation: what are the results?

Abstract Introduction Ventricular tachycardia (VT) endocardial mapping and ablation may not be sufficient in several arrhythmogenic contexts, because ventricular myocardium may comprise intricate endocardial, intramural and epicardial substract. Thus, epicardial ablation has lately become a complementary and necessary tool to approach some VTs in different types of cardiomyopathies. Purposes To evaluate the clinical characteristics of patient most suitable for first intention epicardial VT ablation and to describe our centre experience. Methods Single-centre prospective study of consecutive patients (pts) undergoing isolated first intention epicardial VT mapping and ablation since August 2015. All pts had clinical assessment, electrocardiogram (ECG), echocardiogram and cardiac magnetic resonance when feasible. Pts with a previous endocardial ablation were excluded. Epicardial subxiphoid access utilizing a tuhoy needle was performed under fluoroscopic guidance. High-density mapping was performed using CARTO® V4 and EnSite PrecisionTM systems and multipolar catheters. Radiofrequency energy was applied with an irrigated-tip catheter. Results First intention epicardial VT ablation was attempted in 12 pts (mean age 57.6±14.6 years, 91% male). The majority had non-ischemic dilated cardiomyopathy, of unknown aetiology in 59%, hereditary dilated cardiomyopathy in 17% ethanolic origin in 8% and post-myocarditis in 8%. Right Ventricular Arrhythmogenic Cardiomyopathy was present in 1 patient. As expected, our population presented a mean ejection fraction of 29% and 11 pts (92%) had an implantable cardioverter defibrillator - ICD (55% as primary prevention, 45% as secondary prevention). All pts had experienced symptomatic VT, with all ICD carriers receiving appropriate shocks. Only 4 pts had an available 12 lead ECG of the VT, and all of them had a QS pattern in lead aVL and a slurred initial QRS complex. The majority of patients presented low voltage areas and local abnormal ventricular activities at the epicardial surface, with the exception of 2 pts in whom ablation was not performed (one non-ischemic cardiomyopathy of ethanolic aetiology and the other of unknown origin). Mean ablation application time was 68 minutes, with an average maximum power of 39.9 watts. Mean overall procedure and fluoroscopic time was 132 and 24 minutes, respectively, with no major intraprocedural complications. During a mean follow-up of 307±328 days, 3 pts died (mean 121 days after procedure), 3 had recurrent VT episodes and ICD shocks, and 2 received heart transplant. Conclusion In selected pts, with non-ischemic dilated cardiomyopathy and ECG with QS pattern in aVL and slurred QRS, epicardial VT mapping and ablation may be used as first approach, preventing unnecessary endocardial mapping. This procedure demonstrated to be safe.

Abstract 816: Surgical Bilateral Stellate Ganglionectomy Reduces Mitochondrial Reactive Oxygen Species (mROS) and Prevents Sudden Cardiac Death (SCD) in Non-ischemic Heart Failure (HF)

Introduction: Current therapies for SCD are limited. Bilateral sympathetic stellate ganglionectomy ( BSG ) is a promising new adjunctive therapy in patients with ischemic HF who have incessant ventricular tachyarrhythmias ( VT/VF ) despite optimal medical management. The underlying mechanisms are unknown. The effect of BSG in non-ischemic HF is unclear. Hypothesis: BSG prevents VT/VF and SCD in non-ischemic HF by restoring sympathovagal balance and reducing mROS. Methods: We used a unique pressure-overload guinea pig model that closely mimics human non-ischemic HF, including a high incidence of spontaneous VT/VF/SCD. We randomized the animals to non-failing controls, HF+Sham, or HF+BSG surgery. We used intention to treat analysis to evaluate VT/VF-free survival. We analyzed continuous ECG (VT/VF burden, heart rate variability, QT variability) and echo (cardiac function). In isolated left ventricular (LV) myocytes, we measured Ca 2+ transients and mitochondrial reactive oxygen species (mROS) using targeted ratiometric probes. Results: Half of the HF+Sham animals experienced SCD in 4 weeks. In contrast, BSG abolished SCD, reduced VT/VF, and increased parasympathetic tone (beyond corresponding reductions in sympathetic tone). Fractional shortening of the LV was markedly reduced in HF+Sham (0.28±0.02) vs. control (0.50±0.01), but preserved by BSG (0.45±0.02). Whereas HF+Sham increased mROS levels in LV myocytes (fractional oxidation, F ox : 0.53±0.015) compared to control (0.29±0.020), BSG reduced mROS (0.38±0.035). Mitochondrial antioxidant capacity, as indexed by H 2 O 2 challenge of LV myocytes, was compromised in HF+Sham (F ox : 0.81±0.040) compared to control (0.44±0.061), but preserved by BSG (0.48±0.023). Conclusions: Surgical BSG prevents SCD in non-ischemic HF by reducing mROS, decreasing sympathetic tone, and by increasing parasympathetic tone (possibly by facilitating cholinergic transdifferentiation). This promising new minimally-invasive surgical therapy may be particularly useful in patients with non-ischemic HF on optimal medical therapy who require recurrent ICD shocks to prevent SCD. Patients in the early stages of HF who are not eligible for ICDs but remain at higher SCD risk may also benefit from BSG surgery.

Abstract 115: Surgical Bilateral Stellate Ganglionectomy Reduces Mitochondrial Reactive Oxygen Species (mROS) and Prevents Sudden Cardiac Death (SCD) in Non-ischemic Heart Failure (HF)

Introduction: Current therapies for SCD are limited. Bilateral sympathetic stellate ganglionectomy ( BSG ) is a promising new adjunctive therapy in patients with ischemic HF who have incessant ventricular tachyarrhythmias ( VT/VF ) despite optimal medical management. The underlying mechanisms are unknown. The effect of BSG in non-ischemic HF is unclear. Hypothesis: BSG prevents VT/VF and SCD in non-ischemic HF by restoring sympathovagal balance and reducing mROS . METHODS: We used a unique pressure-overload guinea pig model that closely mimics human non-ischemic HF, including a high incidence of spontaneous VT/VF/SCD. We randomized the animals to non-failing controls, HF+Sham, or HF+BSG surgery. We used intention to treat analysis to evaluate VT/VF-free survival. We analyzed continuous ECG (VT/VF burden, heart rate variability, QT variability) and echo (cardiac function). In isolated left ventricular (LV) myocytes, we measured Ca 2+ transients and mitochondrial reactive oxygen species (mROS) using targeted ratiometric probes. Results: Half of the HF+Sham animals experienced SCD in 4 weeks. In contrast, BSG abolished SCD, reduced VT/VF, and increased parasympathetic tone (beyond corresponding reductions in sympathetic tone). Fractional shortening of the LV was markedly reduced in HF+Sham (0.28±0.02) vs. control (0.50±0.01), but preserved by BSG (0.45±0.02). Whereas HF+Sham increased mROS levels in LV myocytes (fractional oxidation, F ox : 0.53±0.015) compared to control (0.29±0.020), BSG reduced mROS (0.38±0.035). Mitochondrial antioxidant capacity, as indexed by H 2 O 2 challenge of LV myocytes, was compromised in HF+Sham (F ox : 0.81±0.040) compared to control (0.44±0.061), but preserved by BSG (0.48±0.023). Conclusions: Surgical BSG prevents SCD in non-ischemic HF by reducing mROS, decreasing sympathetic tone, and by increasing parasympathetic tone (possibly by facilitating cholinergic transdifferentiation). This promising new minimally-invasive surgical therapy may be particularly useful in patients with non-ischemic HF on optimal medical therapy who require recurrent ICD shocks to prevent SCD. Patients in the early stages of HF who are not eligible for ICDs but remain at higher SCD risk may also benefit from BSG surgery.

Prognostic impact of recurrences of ventricular tachyarrhythmias and appropriate ICD therapies in a high-risk ICD population.

The study sought to evaluate the prognostic impact of recurrences of ventricular tachyarrhythmias in consecutive ICD recipients with ventricular tachyarrhythmias on admission. All consecutive patients surviving at least one episode of ventricular tachyarrhythmias from 2002 to 2016 and discharged with an ICD (pre-existing ICD or ICD implantation at index hospitalization)were included. The primary endpoint was all-cause mortality according to the presence orabsence of recurrences of ventricular tachyarrhythmias at 5years. Secondary endpoints comprised the impact of different types of recurrences, appropriate ICD therapies, as well as predictors of recurrences and appropriate ICD therapies. Kaplan-Meier, multivariable Cox regression and propensity score matching analyses were applied. A total of 592 consecutive ICD recipients was included (44% with recurrences of ventricular tachyarrhythmias and 56% without). Recurrences of ventricular tachyarrhythmias were associated with increased all-cause mortality at 5years (HR = 1.498; 95% CI = 1.052-2.132; p = 0.025). Worst survival was observed in patients with sustained VT or VF as first recurrences compared to non-sustained VT, as well as in patients with cumulative recurrences of non-sustained or sustained VT plus VF, whereas mortality was not affected by the number of recurrences of ventricular tachyarrhythmias (> 4 vs. ≤ 4). Moreover, appropriate ICD therapies were associated with increased all-cause mortality (HR = 1.874; 95% CI = 1.318-2.666; p = 0.001), mainly attributed to secondary preventive ICDs. Finally, atrial fibrillation, LVEF <35% and non-ischemic cardiomyopathy were identified as predictors of recurrences of ventricular tachyarrhythmias and appropriate ICD therapies. Recurrences of ventricular tachyarrhythmias and recurrent appropriate ICD therapies are associated with increased long-term all-cause mortality in consecutive ICD recipients. Non-ischemic cardiomyopathy, AF and LVEF < 35% revealed to be significant predictors of both endpoints.

Electrophysiologic Considerations After Sudden Cardiac Arrest.

Background:Sudden Cardiac Death (SCD) remains a major public health concern, accounting for more than 50% of cardiac deaths. The majority of these deaths are related to ischemic heart disease, however increasingly recognized are non-ischemic causes such as cardiac channelopathies. Bradyarrhythmias and pulseless electrical activity comprise a larger proportion of out-of-hospital arrests than previously realized, particularly in patients with more advanced heart failure or noncardiac triggers such as pulmonary embolism. Patients surviving Sudden Cardiac Arrest (SCA) have a substantial risk of recurrence, particularly within 18 months post event. The timing of tachyarrhythmias complicating acute infarction has important implications regarding the likelihood of recurrence, with those occurring within 48 hours having a more favorable long-term outcome. In the absence of a clear reversible cause, implantable cardioverter defibrillators remain the mainstay in the secondary prevention of SCD. Post defibrillation electromechanical dissociation is common in patients with cardiomyopathy and can lead to SCD despite successful defibrillation of the primary tachyarrhythmia. Antiarrhythmic agents are highly effective in preventing recurrent arrhythmias in specific diseases such as the congenital long QT syndrome.Conclusion:Catheter ablation is used most commonly to prevent recurrent ICD therapies in patients with structural heart disease-related ventricular arrhythmias, however recent publications have shown substantial benefit in other entities such as idiopathic ventricular fibrillation.